• Title/Summary/Keyword: Analysis of variance

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Cephalometric Characteristics of TMD Patients based on RDC/TMD Axis I Diagnosis (RDC/TMD Axis I 진단에 따른 측두하악장애 환자의 측두 두부방사선적 특징에 관한 연구)

  • Ahn, Ji-Yeon;Kim, Yong-Woo;Kim, Young-Ku;Lee, Jeong-Yun
    • Journal of Oral Medicine and Pain
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    • v.36 no.1
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    • pp.39-51
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    • 2011
  • The aims of this study were to investigate whether the facial skeletal patterns previously reported to be related to temporomandibular disorder (TMD) in other studies could be consistently observed in the TMD patients diagnosed according to Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD) Axis I and evaluate its usability in the orthodontic clinics to examine the patients with TMD related symptoms. The clinical records and radiographs of female patients who visited the TMD and Orofacial Pain Clinic of Seoul National University Dental Hospital and were diagnosed as TMD were consecutively filed for this study. Patients were clinically examined and diagnosed according to the revised diagnostic algorithms of RDC/TMD Axis I and the lateral cephalogram, panoramic orthopantomogram, temporomandibular joint (TMJ) orthopantomogram, and transcranial radiograph of each patient were taken and digitalized. The data of patients who were under 18 years of age or had any systemic disease, trauma history involving the TMJ, or skeletal deformity at the time of the first examination were excluded. The remaining data of 96 female patients were finally analyzed. The obtained results were as follows: 1. There are no significant differences of cephalometric measurements between RDC I (muscle disorders) diagnostic groups. 2. Only the articular angle of the RDC group IIc (disk displacement without reduction without limited opening) patients was larger than patients of the no diagnosis of RDC II group (disk displacement). 3. Larger articular angle and smaller facial height ratio were observed in RDC IIIc group (osteoarthrosis) compared to IIIa group (arthralgia). Larger articular angle, larger Bjork sum, smaller posterior facial height, and smaller facial height ratio were observed in RDC group IIIc compared to no diagnosis of RDC III group (arthralgia, arthritis, and arthrosis). 4. According to the results of cephalometric analysis in simplified RDC groups, smaller overjet was observed in muscle disorders (MD) group. Facial height ratio and IMPA were smaller and articular angle was larger in disk displacements (DD) group than in no diagnosis of DD group. In arthrosis (AR) group, posterior facial height, and facial height ratio were smaller, and articular angle, gonial angle, facial convexity, FMA, Bjork sum, and ANB were larger than in no diagnosis of AR group. In joint pain (JP) group, only posterior facial height was smaller than no diagnosis of JP group. In conclusion, Facial morphologic patterns showing posterior-rotated mandible and lower posterior facial height is related to RDC group II and III diagnosis of the TMJ in female TMD patients. RDC/TMD Axis I diagnosis can provide a good clinical diagnostic tool for the standardized examination of the TMJ in orthodontic clinics.

Comparison of Family Support and Mental Health Between the Rural and Urban Elderly (농촌과 도시지역 노인의 가족지지와 정신건강에 관한 비교)

  • Min, Kyung-Hwa;Kim, Sang-Soon
    • Journal of agricultural medicine and community health
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    • v.20 no.2
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    • pp.175-185
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    • 1995
  • This study is to compare family support and mental health between the rural and the urban elderly. In order to do that I collected the data through questioning 238 people in 3 urban areas in Busan and 201 people in 9 rural areas near Daegu. The degree of their family support is 36.70 on the average in the rural area and 40.77 in the urban area. The degree of family support of urban elderly is a little higher. According to general characters between the differences of family support in both areas, in the rural area there are differences in sex, age, whether they have a spouse or not, education level, financial state, number of children, number of co living, status of co living, subjective health status, amount of pocket money and how much they are participating in leisure activity. In the urban area there are differences in sex, whether they have a spouse or not, religion, financial state, number of co living, status of co living, subjective health status, amount of pocket money, how much they are participating in leisure activity and house pattern. In the stepwise multiple regression analysis the main variables that affect degree of family support in the rural area are age, whether they have a spouse or not and financial state which account for 33% of the total variance and in the urban area are subjective health status, financial state, whether they have a spouse or not and number of co-living which account for 35%. Health status is better in the urban area(average 36.87) than in the rural area(57.42). In each item the people whose mark was more than 75%(low) have Depression 8.4%, Somatization 8.0% in the urban area and Somatization 8.5%, Depression 8.5%, Anxiety 4.0%, Phobic anxiety 4.0%, Obsessive compulsive reaction 2.5%, Hostility 2.0%, Paranoid ideation 2.0%, Psychoticism 1.5% and Interpersonal sensitivity 1.5% in the rural area. In the mental health condition, on the basis of 4 points in both areas, the average is Somatization(rural : 1.69, urban : 1.51), Depression (rural : 1.64, urban : 1.37) and Obsessive compulsive reaction(rural : 1.33, urban : 0.99). According to the differences between mental health conditions by general characters, in the rural area the differences are presented in sex, age, whether they have a spouse or not, religion, education level, financial state, number of children, status of co living, subjective health status, amount of pocket money and how much they are participating in leisure activity, in the urban area the differences are presented in sex, whether they have a spouse or not, religion, financial state, number of co living, status of co living, subjective health status, house pattern, amount of pocket money and how much they are participating in leisure activity. In the stepwise multiple regression analysis the main variables that affect mental health condition in the rural are family support degree subjective health status, religion sex, age and financial state which account for 43% of the total and in the urban area are family support degree, subjective health status and financial state which account for 51%. In the matter of family support degree and mental health condition the rural area was -0.4555, of urban area was -0.6446. The rural area that has a high percentage in family support degree and mental health condition Depression was -0.5036, Psychoticism was -0.4265 in the urban area Psychoticism was -0.6452, Depression was -0.5955. Family support has a great influence on mental health of old people and family support and mental health condition can be different according to living area. So in their problems nursing intervention through family and nursing strategies according to living area should be established.

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The Impact of e-Store Personality on e-Store Loyalty-Focus on the Mediating Role of Identification, Trust, and Engagement (온라인에서 점포 개성이 점포 충성도에 미치는 영향-동일시, 신뢰, 인게이지먼트의 매개 역할을 중심으로)

  • Park, Hyo-Hyun;Jung, Gang-Ok;Lee, Seung-Chang
    • Journal of Distribution Research
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    • v.16 no.2
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    • pp.57-94
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    • 2011
  • Nowadays, it is common that most consumers are purchasing goods in e-stores. The e-stores eager to attract, revisit, retain, and finally convert them into loyal customers. The e-store marketers have planned and executed numerous marketing efforts. As one of the marketing activities, e-store managers attempt to build web sites that meet customers' functional and psychological needs. A wide array of studies has been done to identify factors that could affect customers' response of web sites. Majority of studies were conducted to verify technology-related and functional variables of the website which facilitate transactions and enhance customer responses such as purchase intention and website loyalty. However, there has been little research on the external cues of website and psychological variables of consumer that could have positive influences on customer response. The purpose of this study is to investigate the influence of e-store personality on e-store loyalty through mediating variables such as e-store identification, e-store trust, and e-store engagement. The authors of this study develop the model and set up the six main hypotheses and a set of sub-hypotheses based on a literature review, shown in

    . This model is composed of four paths such as dimensions of e-store personality${\rightarrow}$e-store identification, e-store identification${\rightarrow}$e-store loyalty, e-store identification ${\rightarrow}$e-store trust${\rightarrow}$e-store loyalty, and e-store identification${\rightarrow}$e-store engagement${\rightarrow}$e-store loyalty. II. Research Method Ladies under 30s were the respondents of this survey. Data were collected from January 20th to February 26th in 2010. A total of 200 questionnaires were distributed and 169 respondents were analysed finally to test hypotheses because 31 questionnaires had incorrect or missing responses. SPSS 12.0 and LISREL 7.0 program were used to test frequency, reliability, factor, and structural equation modeling analysis. III. Result and Conclusion According to results from factor analysis, eigen value was over 1.0 and items which were below 0.6 were deleted. Consequently, 9 factors(% of total variance is 72.011%) were searched. All Cronbach's ${\alpha}$ values are over the recommended level(${\alpha}$ > 0.7). The overall fit indices are acceptable such as ${\chi}^2$=2028.36(p=0.00), GFI=0.87, AGFI=0.82, CFI=0.81, IFI=0.92, RMR=0.075. All factor loadings were over the recommended level. As the result of discriminant validity check with chi-square difference test between paired constructs, each construct has good discriminant validity. The overall fit indices of final model are acceptable such as ${\chi}^2$=340.73(df=36, p=0.00), GFI=0.92, AGFI=0.81, CFI=0.91, IFI=0.91, RMR=0.085. As test results, 5 out of 6 hypotheses are supported because there are statistically significant casual relationships in structural equation model, shown in . First of all, hypothesis 1 is partially supported because sub-hypothesis 1-1 and 1-2 are supported, whereas sub-hypothesis 1-3, 1-4, and 1-5 are rejected. Specifically, it reveals that warmth and sophistication dimensions in e-store personality have positive influence on e-store identification, however, activity, progressiveness, and strictness does not have any significant relationship on e-store identification. Secondly, hypothesis 2 was supported. Therefore, it can be said that e-store identification has a positive impact on e-store trust. Thirdly, hypothesis 3 is also supported. Hence, there is a positive relationship between e-store identification and e-store engagement. Fourthly, hypothesis 4 is supported too. e-store identification has a positive influence on e-store loyalty. Fifthly, hypothesis 5 is also accepted. This indicates that e-store trust is a precedent variable which positively affects e-store loyalty. Lastly, it reveals that e-store engagement has a positive impact on e-store loyalty. Therefore, hypothesis 6 is supported. The findings of the study imply that some dimensions of e-store personality have a positive influence on e-store identification, and that e-store identification has direct and indirect influence on e-store loyalty through e-store trust and e-store engagement positively. These results also suggest that the e-store identification in e-store personality is a precedent variable which positively affects e-store loyalty directly and indirectly through e-store trust and engagement as a mediating variable. Therefore, e-store marketers need to implement website strategy based on e-store personality, e-store identification, e-store trust, and e-store engagement to meet customers' psychological needs and enhance e-store loyalty. Finally, the limitations and future study directions based on this study are discussed.

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  • Open Skies Policy : A Study on the Alliance Performance and International Competition of FFP (항공자유화정책상 상용고객우대제도의 제휴성과와 국제경쟁에 관한 연구)

    • Suh, Myung-Sun;Cho, Ju-Eun
      • The Korean Journal of Air & Space Law and Policy
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      • v.25 no.2
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      • pp.139-162
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      • 2010
    • In terms of the international air transport, the open skies policy implies freedom in the sky or opening the sky. In the normative respect, the open skies policy is a kind of open-door policy which gives various forms of traffic right to other countries, but on the other hand it is a policy of free competition in the international air transport. Since the Airline Deregulation Act of 1978, the United States has signed an open skies agreement with many countries, starting with the Netherlands, so that competitive large airlines can compete in the international air transport market where there exist a lot of business opportunities. South Korea now has an open skies agreement with more than 20 countries. The frequent flyer program (FFP) is part of a broad-based marketing alliance which has been used as an airfare strategy since the U.S. government's airline deregulation. The membership-based program is an incentive plan that provides mileage points to customers for using airline services and rewards customer loyalty in tangible forms based on their accumulated points. In its early stages, the frequent flyer program was focused on marketing efforts to attract customers, but now in the environment of intense competition among airlines, the program is used as an important strategic marketing tool for enhancing business performance. Therefore, airline companies agree that they need to identify customer needs in order to secure loyal customers more effectively. The outcomes from an airline's frequent flyer program can have a variety of effects on international competition. First, the airline can obtain a more dominant position in the air flight market by expanding its air route networks. Second, the availability of flight products for customers can be improved with an increase in flight frequency. Third, the airline can preferentially expand into new markets and thus gain advantages over its competitors. However, there are few empirical studies on the airline frequent flyer program. Accordingly, this study aims to explore the effects of the program on international competition, after reviewing the types of strategic alliance between airlines. Making strategic airline alliances is a worldwide trend resulting from the open skies policy. South Korea also needs to be making open skies agreements more realistic to promote the growth and competition of domestic airlines. The present study is about the performance of the airline frequent flyer program and international competition under the open skies policy. With a sample of five global alliance groups (Star, Oneworld, Wings, Qualiflyer and Skyteam), the study was attempted as an empirical study of the effects that the resource structures and levels of information technology held by airlines in each group have on the type of alliance, and one-way analysis of variance and regression analysis were used to test hypotheses. The findings of this study suggest that both large airline companies and small/medium-size airlines in an alliance group with global networks and organizations are able to achieve high performance and secure international competitiveness. Airline passengers earn mileage points by using non-flight services through an alliance network with hotels, car-rental services, duty-free shops, travel agents and more and show high interests in and preferences for related service benefits. Therefore, Korean airline companies should develop more aggressive marketing programs based on multilateral alliances with other services including hotels, as well as with other airlines.

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    Decomposition Characteristics of Fungicides(Benomyl) using a Design of Experiment(DOE) in an E-beam Process and Acute Toxicity Assessment (전자빔 공정에서 실험계획법을 이용한 살균제 Benomyl의 제거특성 및 독성평가)

    • Yu, Seung-Ho;Cho, Il-Hyoung;Chang, Soon-Woong;Lee, Si-Jin;Chun, Suk-Young;Kim, Han-Lae
      • Journal of Korean Society of Environmental Engineers
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      • v.30 no.9
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      • pp.955-960
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      • 2008
    • We investigated and estimated at the characteristics of decomposition and mineralization of benomyl using a design of experiment(DOE) based on the general factorial design in an E-beam process, and also the main factors(variables) with benomyl concentration(X$_1$) and E-beam irradiation(X$_2$) which consisted of 5 levels in each factor was set up to estimate the prediction model and the optimization conditions. At frist, the benomyl in all treatment combinations except 17 and 18 trials was almost degraded and the difference in the decomposition of benomyl in the 3 blocks was not significant(p > 0.05, one-way ANOVA). However, the % of benomyl mineralization was 46%(block 1), 36.7%(block 2) and 22%(block 3) and showed the significant difference of the % that between each block(p < 0.05). The linear regression equations of benomyl mineralization in each block were also estimated as followed; block 1(Y$_1$ = 0.024X$_1$ + 34.1(R$^2$ = 0.929)), block 2(Y$_2$ = 0.026X$_2$ + 23.1(R$^2$ = 0.976)) and block 3(Y$_3$ = 0.034X$_3$ + 6.2(R$^2$ = 0.98)). The normality of benomyl mineralization obtained from Anderson-Darling test in all treatment conditions was satisfied(p > 0.05). The results of prediction model and optimization point using the canonical analysis in order to obtain the optimal operation conditions were Y = 39.96 - 9.36X$_1$ + 0.03X$_2$ - 10.67X$_1{^2}$ - 0.001X$_2{^2}$ + 0.011X$_1$X$_2$(R$^2$ = 96.3%, Adjusted R$^2$ = 94.8%) and 57.3% at 0.55 mg/L and 950 Gy, respectively. A Microtox test using V. fischeri showed that the toxicity, expressed as the inhibition(%), was reduced almost completely after an E-beam irradiation, whereas the inhibition(%) for 0.5 mg/L, 1 mg/L and 1.5 mg/L was 10.25%, 20.14% and 26.2% in the initial reactions in the absence of an E-beam illumination.

    Investigation of Food Safety Knowledge, Attitudes, and Behavior for Analyzing Food Safety Risk Factors in the Elderly (노인들의 식품안전 위험요인 규명을 위한 식품위생 지식, 태도, 행동 조사)

    • Choi, Jung-Hwa;Lee, Yoon-Jin;Lee, Eun-Sil;Lee, Hye-Sang;Chang, Hye-Ja;Lee, Kyung-Eun;Yi, Na-Young;Kwak, Tong-Kyung
      • Journal of the Korean Society of Food Science and Nutrition
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      • v.45 no.5
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      • pp.746-756
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      • 2016
    • The purpose of this study was to investigate food safety knowledge, food safety attitudes, and handling behavior in the elderly. The survey was conducted on 358 individuals over 65 years old in urban and rural areas. Data were analyzed with descriptive analysis and ${\chi}^2$ test analysis of variance using SPSS. From the results on elderly's food safety knowledge, the item 'tangerines should be washed before eating' was correctly answered by urban subjects (75.4%) than rural subjects (49.7%). 'Is it okay to cook meat left on the sink since afternoon in the evening' showed the lowest correct answer rate in both urban (23.1%) and rural (31.9%) subjects. For the item related to food keeping, 'Bacterial cells do not multiply in Samgyetang when it is kept in a refrigerator right after boiling thoroughly', 58.5% of urban and 54.6% of rural elderly answered correctly. Most elderly people showed a tendency to think that boiled foods might be safe to eat. Secondly, for food safety attitudes, urban elderly had more proper attitude regarding the item, 'Namul is very tasty only when mixed with bare hands' (disagree rate 34.9%) than rural elderly (P<0.05)'. On the other hand, rural elderly had more positive attitudes regarding the store principle "first in, first out" compared to urban elderly (P<0.001). Thirdly, regarding food safety behaviors, only 67.9% of urban and 58.7% of rural elderly responded that they washed their hands right after answering the telephone while cooking. Exactly 33.8% of urban and 39.6% of rural older people replied 'defrost meat on top of sink or table' as the defrost method for frozen foods, showing that elderly did not recognize the risk of foodborne illness during improper defrosting at room temperature.

    Studies on Genetic Analysis by the Diallel Crosses in $F_2$ Generation of Cowpea(Vigna sinensis savi.) (동부 Diallel Cross$ F_2$세대의 유전분석에 관한 연구)

    • Kim, J.H.;Ko, M.S.;Chang, K.Y.
      • KOREAN JOURNAL OF CROP SCIENCE
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      • v.28 no.2
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      • pp.216-226
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      • 1983
    • Genetic studies on the $F_2$ generation of a set of half diallel crosses involving six cowpea varieties were conducted. by the randomized block design with three replications to determine combining ability, gene action and the relationships between parents and their $F_2$ hybrids. The 12 agronomic characters namely, days to flowering, days from flowering to maturity, days to maturity, diameter of stem, length of internode, number of branches per plant, length of pod, number of pods per plant, number of grains per pod, number of grains per plant, 100 grain weight and grain weight per plot were observed, and the $F_2$ generation of this diallel set of crosses was analysed for each character according to the method by Jinks and Hayman. The results obtained are summarized as follows: 1. Vr-Wr graphical analyses; The following seven characters, days to flowering, number of branches per plant, length of pod, number of pods per plant, number of grains per plant, 100 grain weight and grain weight per plot appeared to be partially dominant, and over dominance was found for days from flowering to maturity, days to maturity, length of internode and number of grains per pod. But diameter of stem indicated partial dominance near complete dominance. 2. Estimates of genetic variance components; In the degree of dominance,. eight characters, that is, days to flowering, days from flowering to maturity, days to maturity, length of internode, number of pods per plant, number of grains per pod, number of grains per plant and grain weight per plot were expressed larger than 1. And the characters, days from flowering to maturity, number of branches per plant and number of grains per plant as the degree of mean dominance ($H_1$/D) were found to be negative value over other characters. On the other hand, apprent asymmetry of dominance-recessive allele ($H_2$ /$4H_1$) produced comparatively estimates with lower value on days from flowering to maturity, length of internode, number of branches per plant and number of grains per pod. 3. Analyses of combining ability; Mean square value of GCA(general combining ability) appeared to be more important than those of SCA (specific combining ability) for most characters, and among them, grain weight per plot showed the highest mean square value in GCA and SCA. 4. Effect of combining ability; Variety 178 was expressed as the highest GCA effects in five characters (days to flowering days to maturity, number of pods per plant, number of grains per plant and grain weight per plot). SCA effects were differed from parents, characters and crosses, but crosses between TVu 1857 $\times$ TVu 2885 and TVu 2702 $\times$ J78 were shown to be highly with SCA effects on yield.

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    Studies on the Interspecific Grafting of Almond (Almond의 종간접목(種間接木)에 관(關)한 연구(硏究))

    • Park, Kyo Soo
      • Journal of Korean Society of Forest Science
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      • v.41 no.1
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      • pp.7-18
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      • 1979
    • Almonds are one of the oldest sources of food and oil for man as used the ice cream, candy, roast, salting, chocolate, breads, backed, cookies, and flavoring ect. So, we wish to plant Almond in our country at the most parts of mountains. In this purpose we must be find out of both root stock of more compatibility and new techniques of grafting was rather simples as compared with the many steps of machinary involved today. This investigation has been carried out to reveral compatibility and practical controls of environment effectives involved in the occurence of each difference combination results in interspecific grafting of Almonds on the root stock of Prunus mandshurica and Prunus persica as materials during the 9 months period from March to November in 1978. With these selected scions were 4 varieties of Almond employing as the Hal1's hardy, Nonpareil, and Thompson grafted in the polyethylene green house with almost identical provision made for effective controls of automatical supplying to heating and mistsprayers as the $22{\sim}25^{\circ}C$ of temperature and 70~90% humidity. Following results have been obtained. Those environmental controls were more effective and practical to grafting unions and success by means veneer-grafting at the green house. 1. Hall's hardy Almond grafted on the root stock of Prunus persica was more compatibility than Prunus mandshurica. 2. The survival percentages as follows of the 95.33% of Hall's hardy/Prunus persica and 92.66% of Hall's hardy/Prunus mandshurica. And those were no significant between root stock of both species. 3. The 3 varieties of sweet Almond grafted on the root stock of P. mandshurica. And those were no significant between root stock of both species. 4. And the survival percentages as fellows. Thompson 92.66%, Nonpareil 90.66% and Kapareil 89.33% those grafted on the root stock of Prunus persica. 5. And then the survival percentage of interspecific grafts on the root Prunus mandshurica as follows of the materials of Thompson 89.66%, Nonpareil 87%, Kapareil 85%. 6. The analysis of variance were no significant among the interactions between 3 varieties Almond and 2 species of root stock plants. 7. And the growth of interspecific grafts of the high 161cm, diameter 12.3mm and length of roots 21.5cm growth as the Hall's hardy Almond grafted on the root stock of Prunus persica. 8. The root stock plants of Prunus mandshurica more effected to 6~8 days early developed leafing of scions and dark green colour than the Prunus persica. 9. The identical provision of automatic systems was more effective to graft unions and grafting process. 10. The veneer-grafting method at the green house was more effective and practical method for the mass production of Almond grafts.

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    A Study on Risk Parity Asset Allocation Model with XGBoos (XGBoost를 활용한 리스크패리티 자산배분 모형에 관한 연구)

    • Kim, Younghoon;Choi, HeungSik;Kim, SunWoong
      • Journal of Intelligence and Information Systems
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      • v.26 no.1
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      • pp.135-149
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      • 2020
    • Artificial intelligences are changing world. Financial market is also not an exception. Robo-Advisor is actively being developed, making up the weakness of traditional asset allocation methods and replacing the parts that are difficult for the traditional methods. It makes automated investment decisions with artificial intelligence algorithms and is used with various asset allocation models such as mean-variance model, Black-Litterman model and risk parity model. Risk parity model is a typical risk-based asset allocation model which is focused on the volatility of assets. It avoids investment risk structurally. So it has stability in the management of large size fund and it has been widely used in financial field. XGBoost model is a parallel tree-boosting method. It is an optimized gradient boosting model designed to be highly efficient and flexible. It not only makes billions of examples in limited memory environments but is also very fast to learn compared to traditional boosting methods. It is frequently used in various fields of data analysis and has a lot of advantages. So in this study, we propose a new asset allocation model that combines risk parity model and XGBoost machine learning model. This model uses XGBoost to predict the risk of assets and applies the predictive risk to the process of covariance estimation. There are estimated errors between the estimation period and the actual investment period because the optimized asset allocation model estimates the proportion of investments based on historical data. these estimated errors adversely affect the optimized portfolio performance. This study aims to improve the stability and portfolio performance of the model by predicting the volatility of the next investment period and reducing estimated errors of optimized asset allocation model. As a result, it narrows the gap between theory and practice and proposes a more advanced asset allocation model. In this study, we used the Korean stock market price data for a total of 17 years from 2003 to 2019 for the empirical test of the suggested model. The data sets are specifically composed of energy, finance, IT, industrial, material, telecommunication, utility, consumer, health care and staple sectors. We accumulated the value of prediction using moving-window method by 1,000 in-sample and 20 out-of-sample, so we produced a total of 154 rebalancing back-testing results. We analyzed portfolio performance in terms of cumulative rate of return and got a lot of sample data because of long period results. Comparing with traditional risk parity model, this experiment recorded improvements in both cumulative yield and reduction of estimated errors. The total cumulative return is 45.748%, about 5% higher than that of risk parity model and also the estimated errors are reduced in 9 out of 10 industry sectors. The reduction of estimated errors increases stability of the model and makes it easy to apply in practical investment. The results of the experiment showed improvement of portfolio performance by reducing the estimated errors of the optimized asset allocation model. Many financial models and asset allocation models are limited in practical investment because of the most fundamental question of whether the past characteristics of assets will continue into the future in the changing financial market. However, this study not only takes advantage of traditional asset allocation models, but also supplements the limitations of traditional methods and increases stability by predicting the risks of assets with the latest algorithm. There are various studies on parametric estimation methods to reduce the estimated errors in the portfolio optimization. We also suggested a new method to reduce estimated errors in optimized asset allocation model using machine learning. So this study is meaningful in that it proposes an advanced artificial intelligence asset allocation model for the fast-developing financial markets.

    The Effects of Environmental Dynamism on Supply Chain Commitment in the High-tech Industry: The Roles of Flexibility and Dependence (첨단산업의 환경동태성이 공급체인의 결속에 미치는 영향: 유연성과 의존성의 역할)

    • Kim, Sang-Deok;Ji, Seong-Goo
      • Journal of Global Scholars of Marketing Science
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      • v.17 no.2
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      • pp.31-54
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      • 2007
    • The exchange between buyers and sellers in the industrial market is changing from short-term to long-term relationships. Long-term relationships are governed mainly by formal contracts or informal agreements, but many scholars are now asserting that controlling relationship by using formal contracts under environmental dynamism is inappropriate. In this case, partners will depend on each other's flexibility or interdependence. The former, flexibility, provides a general frame of reference, order, and standards against which to guide and assess appropriate behavior in dynamic and ambiguous situations, thus motivating the value-oriented performance goals shared between partners. It is based on social sacrifices, which can potentially minimize any opportunistic behaviors. The later, interdependence, means that each firm possesses a high level of dependence in an dynamic channel relationship. When interdependence is high in magnitude and symmetric, each firm enjoys a high level of power and the bonds between the firms should be reasonably strong. Strong shared power is likely to promote commitment because of the common interests, attention, and support found in such channel relationships. This study deals with environmental dynamism in high-tech industry. Firms in the high-tech industry regard it as a key success factor to successfully cope with environmental changes. However, due to the lack of studies dealing with environmental dynamism and supply chain commitment in the high-tech industry, it is very difficult to find effective strategies to cope with them. This paper presents the results of an empirical study on the relationship between environmental dynamism and supply chain commitment in the high-tech industry. We examined the effects of consumer, competitor, and technological dynamism on supply chain commitment. Additionally, we examined the moderating effects of flexibility and dependence of supply chains. This study was confined to the type of high-tech industry which has the characteristics of rapid technology change and short product lifecycle. Flexibility among the firms of this industry, having the characteristic of hard and fast growth, is more important here than among any other industry. Thus, a variety of environmental dynamism can affect a supply chain relationship. The industries targeted industries were electronic parts, metal product, computer, electric machine, automobile, and medical precision manufacturing industries. Data was collected as follows. During the survey, the researchers managed to obtain the list of parts suppliers of 2 companies, N and L, with an international competitiveness in the mobile phone manufacturing industry; and of the suppliers in a business relationship with S company, a semiconductor manufacturing company. They were asked to respond to the survey via telephone and e-mail. During the two month period of February-April 2006, we were able to collect data from 44 companies. The respondents were restricted to direct dealing authorities and subcontractor company (the supplier) staff with at least three months of dealing experience with a manufacture (an industrial material buyer). The measurement validation procedures included scale reliability; discriminant and convergent validity were used to validate measures. Also, the reliability measurements traditionally employed, such as the Cronbach's alpha, were used. All the reliabilities were greater than.70. A series of exploratory factor analyses was conducted. We conducted confirmatory factor analyses to assess the validity of our measurements. A series of chi-square difference tests were conducted so that the discriminant validity could be ensured. For each pair, we estimated two models-an unconstrained model and a constrained model-and compared the two model fits. All these tests supported discriminant validity. Also, all items loaded significantly on their respective constructs, providing support for convergent validity. We then examined composite reliability and average variance extracted (AVE). The composite reliability of each construct was greater than.70. The AVE of each construct was greater than.50. According to the multiple regression analysis, customer dynamism had a negative effect and competitor dynamism had a positive effect on a supplier's commitment. In addition, flexibility and dependence had significant moderating effects on customer and competitor dynamism. On the other hand, all hypotheses about technological dynamism had no significant effects on commitment. In other words, technological dynamism had no direct effect on supplier's commitment and was not moderated by the flexibility and dependence of the supply chain. This study makes its contribution in the point of view that this is a rare study on environmental dynamism and supply chain commitment in the field of high-tech industry. Especially, this study verified the effects of three sectors of environmental dynamism on supplier's commitment. Also, it empirically tested how the effects were moderated by flexibility and dependence. The results showed that flexibility and interdependence had a role to strengthen supplier's commitment under environmental dynamism in high-tech industry. Thus relationship managers in high-tech industry should make supply chain relationship flexible and interdependent. The limitations of the study are as follows; First, about the research setting, the study was conducted with high-tech industry, in which the direction of the change in the power balance of supply chain dyads is usually determined by manufacturers. So we have a difficulty with generalization. We need to control the power structure between partners in a future study. Secondly, about flexibility, we treated it throughout the paper as positive, but it can also be negative, i.e. violating an agreement or moving, but in the wrong direction, etc. Therefore we need to investigate the multi-dimensionality of flexibility in future research.

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