• Title/Summary/Keyword: Combining function

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The effects of synbiotics-glyconutrients on growth performance, nutrient digestibility, gas emission, meat quality, and fatty acid profile of finishing pigs

  • Olivier Munezero;Sungbo Cho;In Ho Kim
    • Journal of Animal Science and Technology
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    • v.66 no.2
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    • pp.310-325
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    • 2024
  • Glyconutrients help in the body's cell communication. Glyconutrients and synbiotics are promising options for improving immune function. Therefore, we hypothesized that combining synbiotics and glyconutrients will enhance pig nutrient utilization. 150 pigs (Landrace × Yorkshire × Duroc), initially weighing 58.85 ± 3.30 kg of live body weight (BW) were utilized to determine the effects of synbiotics-glyconutrients (SGN) on the pigs' performance, feed efficiency, gas emission, pork traits, and composition of fatty acids. The pigs were matched by BW and sex and chosen at random to 1 of 3 diet treatments: control = Basal diet; TRT1 = Basal diet + SGN 0.15%; TRT2 = Basal diet + SGN 0.30%%. The trials were conducted in two phases (weeks 1-5 and weeks 5-10). The average daily gain was increased in pigs fed a basal diet with SGN (p = 0.036) in weeks 5-10. However, the apparent total tract digestibility of dry matter, nitrogen, and gross energy did not differ among the treatments (p > 0.05). Dietary treatments had no effect on NH3, H2S, methyl mercaptans, acetic acids, and CO2 emissions (p > 0.05). Improvement in drip loss on day 7 (p = 0.053) and tendency in the cooking loss were observed (p = 0.070) in a group fed basal diets and SGN at 0.30% inclusion level. The group supplemented with 0.30% of SGN had higher levels of palmitoleic acid (C16:1), margaric acid (C17:0), omega-3 fatty acid, omega-6 fatty acid, and ω-6: ω-3 ratio (p = 0.034, 0.020, 0.025, 0.007, and 0.003, respectively) in the fat of finishing pigs. Furthermore, group supplemented with 0.30% of SGN improved margaric acid (C17:0), linoleic acid (C18:2n6c), arachidic acid (C20:0), omega 6 fatty acid, omega-6 to omega-3 ratio, unsaturated fatty acid, and monounsaturated fatty acid (p = 0.037, 0.05, 0.0142, 0.036, 0.033, 0.020, and 0.045, respectively) in the lean tissues of finishing pigs compared to pigs fed with the control diets. In conclusion, the combination of probiotics, prebiotics, and glyconutrients led to higher average daily gain, improved the quality of pork, and more favorable fatty acid composition. Therefore, these results contributed to a better understanding of the potential of SGN combinations as a feed additive for pigs.

Bankruptcy prediction using an improved bagging ensemble (개선된 배깅 앙상블을 활용한 기업부도예측)

  • Min, Sung-Hwan
    • Journal of Intelligence and Information Systems
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    • v.20 no.4
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    • pp.121-139
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    • 2014
  • Predicting corporate failure has been an important topic in accounting and finance. The costs associated with bankruptcy are high, so the accuracy of bankruptcy prediction is greatly important for financial institutions. Lots of researchers have dealt with the topic associated with bankruptcy prediction in the past three decades. The current research attempts to use ensemble models for improving the performance of bankruptcy prediction. Ensemble classification is to combine individually trained classifiers in order to gain more accurate prediction than individual models. Ensemble techniques are shown to be very useful for improving the generalization ability of the classifier. Bagging is the most commonly used methods for constructing ensemble classifiers. In bagging, the different training data subsets are randomly drawn with replacement from the original training dataset. Base classifiers are trained on the different bootstrap samples. Instance selection is to select critical instances while deleting and removing irrelevant and harmful instances from the original set. Instance selection and bagging are quite well known in data mining. However, few studies have dealt with the integration of instance selection and bagging. This study proposes an improved bagging ensemble based on instance selection using genetic algorithms (GA) for improving the performance of SVM. GA is an efficient optimization procedure based on the theory of natural selection and evolution. GA uses the idea of survival of the fittest by progressively accepting better solutions to the problems. GA searches by maintaining a population of solutions from which better solutions are created rather than making incremental changes to a single solution to the problem. The initial solution population is generated randomly and evolves into the next generation by genetic operators such as selection, crossover and mutation. The solutions coded by strings are evaluated by the fitness function. The proposed model consists of two phases: GA based Instance Selection and Instance based Bagging. In the first phase, GA is used to select optimal instance subset that is used as input data of bagging model. In this study, the chromosome is encoded as a form of binary string for the instance subset. In this phase, the population size was set to 100 while maximum number of generations was set to 150. We set the crossover rate and mutation rate to 0.7 and 0.1 respectively. We used the prediction accuracy of model as the fitness function of GA. SVM model is trained on training data set using the selected instance subset. The prediction accuracy of SVM model over test data set is used as fitness value in order to avoid overfitting. In the second phase, we used the optimal instance subset selected in the first phase as input data of bagging model. We used SVM model as base classifier for bagging ensemble. The majority voting scheme was used as a combining method in this study. This study applies the proposed model to the bankruptcy prediction problem using a real data set from Korean companies. The research data used in this study contains 1832 externally non-audited firms which filed for bankruptcy (916 cases) and non-bankruptcy (916 cases). Financial ratios categorized as stability, profitability, growth, activity and cash flow were investigated through literature review and basic statistical methods and we selected 8 financial ratios as the final input variables. We separated the whole data into three subsets as training, test and validation data set. In this study, we compared the proposed model with several comparative models including the simple individual SVM model, the simple bagging model and the instance selection based SVM model. The McNemar tests were used to examine whether the proposed model significantly outperforms the other models. The experimental results show that the proposed model outperforms the other models.

Optimal Selection of Classifier Ensemble Using Genetic Algorithms (유전자 알고리즘을 이용한 분류자 앙상블의 최적 선택)

  • Kim, Myung-Jong
    • Journal of Intelligence and Information Systems
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    • v.16 no.4
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    • pp.99-112
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    • 2010
  • Ensemble learning is a method for improving the performance of classification and prediction algorithms. It is a method for finding a highly accurateclassifier on the training set by constructing and combining an ensemble of weak classifiers, each of which needs only to be moderately accurate on the training set. Ensemble learning has received considerable attention from machine learning and artificial intelligence fields because of its remarkable performance improvement and flexible integration with the traditional learning algorithms such as decision tree (DT), neural networks (NN), and SVM, etc. In those researches, all of DT ensemble studies have demonstrated impressive improvements in the generalization behavior of DT, while NN and SVM ensemble studies have not shown remarkable performance as shown in DT ensembles. Recently, several works have reported that the performance of ensemble can be degraded where multiple classifiers of an ensemble are highly correlated with, and thereby result in multicollinearity problem, which leads to performance degradation of the ensemble. They have also proposed the differentiated learning strategies to cope with performance degradation problem. Hansen and Salamon (1990) insisted that it is necessary and sufficient for the performance enhancement of an ensemble that the ensemble should contain diverse classifiers. Breiman (1996) explored that ensemble learning can increase the performance of unstable learning algorithms, but does not show remarkable performance improvement on stable learning algorithms. Unstable learning algorithms such as decision tree learners are sensitive to the change of the training data, and thus small changes in the training data can yield large changes in the generated classifiers. Therefore, ensemble with unstable learning algorithms can guarantee some diversity among the classifiers. To the contrary, stable learning algorithms such as NN and SVM generate similar classifiers in spite of small changes of the training data, and thus the correlation among the resulting classifiers is very high. This high correlation results in multicollinearity problem, which leads to performance degradation of the ensemble. Kim,s work (2009) showedthe performance comparison in bankruptcy prediction on Korea firms using tradition prediction algorithms such as NN, DT, and SVM. It reports that stable learning algorithms such as NN and SVM have higher predictability than the unstable DT. Meanwhile, with respect to their ensemble learning, DT ensemble shows the more improved performance than NN and SVM ensemble. Further analysis with variance inflation factor (VIF) analysis empirically proves that performance degradation of ensemble is due to multicollinearity problem. It also proposes that optimization of ensemble is needed to cope with such a problem. This paper proposes a hybrid system for coverage optimization of NN ensemble (CO-NN) in order to improve the performance of NN ensemble. Coverage optimization is a technique of choosing a sub-ensemble from an original ensemble to guarantee the diversity of classifiers in coverage optimization process. CO-NN uses GA which has been widely used for various optimization problems to deal with the coverage optimization problem. The GA chromosomes for the coverage optimization are encoded into binary strings, each bit of which indicates individual classifier. The fitness function is defined as maximization of error reduction and a constraint of variance inflation factor (VIF), which is one of the generally used methods to measure multicollinearity, is added to insure the diversity of classifiers by removing high correlation among the classifiers. We use Microsoft Excel and the GAs software package called Evolver. Experiments on company failure prediction have shown that CO-NN is effectively applied in the stable performance enhancement of NNensembles through the choice of classifiers by considering the correlations of the ensemble. The classifiers which have the potential multicollinearity problem are removed by the coverage optimization process of CO-NN and thereby CO-NN has shown higher performance than a single NN classifier and NN ensemble at 1% significance level, and DT ensemble at 5% significance level. However, there remain further research issues. First, decision optimization process to find optimal combination function should be considered in further research. Secondly, various learning strategies to deal with data noise should be introduced in more advanced further researches in the future.

A Study on the Naejeong (內庭) of Daesoon Jinrihoe Temple Complexes: Focusing on Literary Sources and Context (대순진리회 도장 건축물 내정(內庭)에 대한 연구 - 내정의 문헌 출처와 그 맥락을 중심으로 -)

  • Cha, Seon-keun
    • Journal of the Daesoon Academy of Sciences
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    • v.37
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    • pp.1-52
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    • 2021
  • The Naejeong, the inner court, which is one of the structures found in the temple complexes of Daesoon Jinrihoe. It serves the function of leading and controlling the operation and direction of Korean religions in general. Considering that the dictionary meaning of 'Naejeong' is 'a place to manage the affairs of the state from inside a palace,' the name and function of the structure appear to be in harmony. However, in the Daesoon Jinrihoe context, it is said that the name 'Naejeong (內庭 'Neiting' in Chinese)' is related to a verse from a Daoist scripture. It has not been revealed whether or not the scripture is historical, and what contents or contextual meanings it contains. This study tries to pursue this matter and introduce the original source of the Naejeong in Daesoon Jinrihoe as likely coming from Qianbapinxianjing (前八品仙經, The Former Scripture of the Eight Phases That Reveal the Means to Acquire Immortality). This scripture was compiled in Lüzu-quanshu(呂祖全書, The Entire Collection of Ancestor Lü). This text and its contextual meanings will also be examined. The origin of Qianbapinxianjing dates back to either the late Ming Dynasty or the early Qing. In those days, there existed a group of literati who worshipped Ancestor Lü because he had saved people and taught the art of immortality. The group organized Daoist Spirit-Writing Altars (鸞壇道敎) and invoked the spirit of Ancestor Lü. They were said to have been taught through messages received from spirit-writing sessions (降乩) with Ancestor Lü and several Daoist scriptures were composed by them in this manner. At Immortals-Gathering Pavilion (集仙樓) of Wandian (萬店) in Guangling (廣陵), China, some literati in that group conducted a spirit-writing session with Ancestor Lü between 1589 and 1626, and they produced a scripture which contained the passage, "A crow and a rabbit gather in the middle valley (烏兎結中谷) while a turtle entwined with a snake is in the inner court (龜蛇盤內庭)." They titled the scripture, The Five Movements and Filial Piety (五行端孝). This passage symbolically expresses the accomplishment of immortality in Neidan (internal alchemy) which, within the human body, combines the two energies of yin and yang which are Water and Fire in the Five Movements scheme. This kind of cultivation is said to be achieved only by maintaining the highest possible degree of filial piety. In this context, the Naejeong where a turtle is entwined with a snake (龜蛇合體) was a term that symbolically depicted a place wherein one transforms into an immortal through cultivation. The Five Movements and Filial Piety was included in Qianbapinxianjing after it had been compiled with the other scriptures containing Ancestor Lü's teachings. In 1744, Qianbapinxianjing was included in Lüzu-quanshu, the entire 32-volume collection of Ancestor Lü and printed for the first time. This underlies the belief in Ancestor Lü (呂祖信仰) which embraces the idea of the redemption of people, teaches the arts of immortality, and features Daoist Spirit-Writing Altars, filial piety, the art of Neidan, and the combination of Water and Fire.

The Infrared Medium-deep Survey. VIII. Quasar Luminosity Function at z ~ 5

  • Kim, Yongjung;Im, Myungshin;Jeon, Yiseul;Kim, Minjin;Pak, Soojong;Hyun, Minhee;Taak, Yoon Chan;Shin, Suhyun;Lim, Gu;Paek, Gregory S.H.;Paek, Insu;Jiang, Linhua;Choi, Changsu;Hong, Jueun;Ji, Tae-Geun;Jun, Hyunsung D.;Karouzos, Marios;Kim, Dohyeong;Kim, Duho;Kim, Jae-Woo;Kim, Ji Hoon;Lee, Hye-In;Lee, Seong-Kook;Park, Won-Kee;Yoon, Yongmin;Byeon, Seoyeon;Hwang, Sungyong;Kim, Joonho;Kim, Sophia;Park, Woojin
    • The Bulletin of The Korean Astronomical Society
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    • v.45 no.1
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    • pp.34.3-34.3
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    • 2020
  • Faint z ~ 5 quasars with M1450 ~ -23 mag are known to be the potentially important contributors to the ultraviolet ionizing background in the post-reionization era. However, their number density has not been well determined, making it difficult to assess their role in the early ionization of the intergalactic medium (IGM). In this work, we present the updated results of our z ~ 5 quasar survey using the Infrared Medium-deep Survey (IMS), a near-infrared imaging survey covering an area of 85 square degrees. From our spectroscopic observations with the Gemini Multi-Object Spectrograph (GMOS) on the Gemini-South 8 m Telescope, we discovered eight new quasars at z ~ 5 with -26.1 ≤ M1450 ≤ -23.3. Combining our IMS faint quasars with the brighter Sloan Digital Sky Survey (SDSS) quasars, we derive, for the first time, the z ~ 5 quasar luminosity function (QLF) without any fixed parameters down to the magnitude limit of M1450 = -23 mag. We find that the faint-end slope of the QLF is very flat (-1.2) with a characteristic luminosity of -25.7 mag. The number density of z ~ 5 quasars from the QLF gives lower ionizing emissivity and ionizing photon density than those in previous works. These results imply that quasars are responsible for only 10-20% of the photons required to completely ionize the IGM at z ~ 5, disfavoring the idea that quasars alone could have ionized the IGM at z ~ 5.

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Effect of the Influential Factors on Brand Equity (브랜드 자산가치의 형성에 미치는 영향요인에 관한 연구)

  • Kang, Seuk-Jung
    • Journal of Global Scholars of Marketing Science
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    • v.8
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    • pp.233-267
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    • 2001
  • The management environment in Korea today is undergoing rapid changes; in particular, domestic corporations and businesses are confronting formidable adversity with IMF crisis and WTO. Though cost cutback, higher quality, rapid production, and diversification of products were accepted as important requirements for competitiveness in the past, they have been replaced by brand power. Consumption patterns have changed their focus from function to image orientation. This is why managers in corporations have invested enormous amounts of resources into producing powerful brands, which can attract consumers' attention greatly enough to improve the image of their products. Brands are regarded as a vital vehicle for marketing strategies and thus as a legal asset. Brands with remarkable and favorable image can secure a loyal consumer groups stable revenues. M & A, currently active between corporations, makes brand equity all the more important. The purpose of the present study was to investigate the effect of internal marketing and increased brand diversification on brand equity by combining them as influential factors with marketing mix factor. For this purpose, literature review was make on previous fragmented studies of influential factors on brand equity build-up. Based on the findings of this study, some operational implications were suggested for marketing managers. The findings and implications of the present study are as follows; First, efficient communication among organization members was found to have a significant effect on product quality. Second, job satisfaction and efficient communication among members was shown to significantly influence price policies. Thirdly, efficient communication among organization workers proved to have a significant effect on distribution strategies. Forth, efficient communication among members was demonstrated to significantly influence advertisement and other public-relations activities. Fifth, opacity of market environment appeared to have a significant effect on product quality, prior market entrance as perceived by organization members turned to be of negative influence on product quality. Sixth, opacity of market environment was found to have a significant effect on price policies. Seventh, opacity of market environment was shown to be of significant effect on distribution strategies. Eighth, grater opacity of market environment proved to improve advertisement and other public-relations activities. Ninth, price policies, distribution strategies, advertisement and public-relations activities were found to have a significant effect on brand equity value. To sum up these findings, in order for corporations and businesses to cope with consumers' needs that are increasingly segmented, internal marketing strategies and brand diversification should be implemented so as to generate greater synergy effect. It is also important to stress that differentiated, higher competitiveness should be secured for Korean corporations and businesses to survive in the drastically changing, globalized market environment. In this regard, continuous and long-term management strategies for brand equity build-up should be ensured and is essential in the present unlimited competition. The last but not least important point to notice is that to increase brand equity value, intensive investment and constant emphasis should be made on internal marketing management on intra-organizational members before strengthening external marketing.

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The Risk Implication of Ownership Structure: Focused on Korean Life Insurance Companies (유배당보험상품에 대한 재무론적 분석)

  • Lee, Kun-Ho;Wee, Kyeong-Woo;Jun, Sang-Gyung
    • The Korean Journal of Financial Management
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    • v.24 no.2
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    • pp.147-181
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    • 2007
  • Our article investigates the risk implication of ownership structure in life insurance companies. We set up a model to identify the priority structure of policyholder's and shareholder's cashflow claims, and to derive its implications. Current literature on this issue has focused on the agency paradigm or the risk-sharing efficiency. Fama and Jensen(1983a, 1983b) and Mayers and Smith(1981, 1986, 1988, 1990, 1994) argue that the survival of both the corporate and the mutual form of organization is due in part to the relative efficiencies in controlling agency problems. With regard to insurance business, agency problems arise because of the three functions inherent in the organizations:manager, risk-bearer(owner), and policyholder. Stock insurers are characterized by the potentially complete separation of all three functions while mutual insurers merger the policyholder with the ownership function. Doherty and Dionne(1993) and Doherty(1991) concentrate their analysis on differences in the efficiency of risk sharing between participating and non-participating policies. They argue that when the undiversifiable risk has higher portion in business risk, combining policy and equity claims into a single package is a more efficient risk-sharing contract than a simple prepaid risk-transfer. Among various methods for assembling the policy/equity package, Doherty and Dionne(1993) and Doherty(1991) suggest that policy/equity package offered by the mutual is the most efficient risk-sharing arrangement. There has been a controversy on the property of participating policies sold by life insurance corporations in Korea. Some scholars argue that participating policyholders of Korean life insurance companies have shared the cashflow risk with shareholders. They emphasize that insurance firms have used dividend reserves to supplement for equity deficits. Thus, they argue that the economic entities of Korean life insurance companies are mutual companies though their legal entities are corporations. Our article explicitly sets up each stakeholder's cashflow claim in stock and mutual insurers, and thus identify risk differences in shareholder and policyholder. Using our model, we could derive direct implications on the controversy. Our model shows that life insurance companies would sell participating policies since policyholders would have the incentive to share the risk inherent in their primary claims with equityholders. And there exists a fundamental difference in shareholder's risk and equityholder's.

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Arterial Switch Operation in Patients with Intramural Coronary Artery: Early and Mid-term Results

  • Kim, Hyung-Tae;Sung, Si-Chan;Kim, Si-Ho;Chang, Yun-Hee;Ahn, Hyo-Yeong;Lee, Hyoung-Doo
    • Journal of Chest Surgery
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    • v.44 no.2
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    • pp.115-122
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    • 2011
  • Background: The intramural coronary artery has been known as a risk factor for early death after an arterial switch operation (ASO). We reviewed the morphological characteristics and evaluated the early and mid-term results of ASO for patients with an intramural coronary artery. Materials and Methods: From March 1994 to September 15th 2010, 158 patients underwent ASO at Dong-A and Pusan National University Hospitals for repair of transposition of the great arteries and double outlet right ventricle. Among these patients, 14 patients (8.9%) had an intramural coronary artery. Mean age at operation was $13.4{\pm}10.2$ days (4 to 39 days) and mean body weight was $3.48{\pm}0.33$ kg (2.88 to 3.88 kg). All patients except one were male. Eight patients had TGA/IVS and 4 patients had an aortic arch anomaly. Two patients (14.3%) had side-by-side great artery relation, of whom one had an intramural right coronary artery and the other had an intramural left anterior descending coronary artery. Twelve patients had anterior-posterior relation, all of whom had an intramural left coronary artery (LCA). The aortocoronary flap technique was used in coronary transfer in 8 patients, of whom one patient required a switch to the individual coronary button technique 2 days after operation because of myocardial ischemia. An individual coronary button implantation technique was adopted in 6, of whom 2 patients required left subclavian artery free graft to LCA during the same operation due to LCA injury during coronary button mobilization and LCA torsion. Results: There was 1 operative death (7.1%), which occurred in the first patient in our series. This patient underwent an aortocoronary flap procedure for coronary transfer combining aortic arch repair. Overall operative mortality for 144 patients without an intramural coronary artery was 13.2% (19/144). There was no statistical difference in operative mortality between the patients with and without an intramural coronary artery (p>0.1). There was no late death. The mean follow-up duration was $52.1{\pm}43.0$ months (0.5 to 132 months). One patient who had a subclavian artery free graft required LCA stenting 6.5 years after surgery for LCA anastomotic site stenosis. No other surviving patient needed any intervention for coronary problems. All patients had normal ventricular function at latest echocardiography and were in NYHA class 1. Conclusion: The arterial switch operation in Transposition of Great Arteries or Double Outlet Right Ventricle patients with intramural coronary can be performed with low mortality; however, there is a high incidence of intraoperative or postoperative coronary problems, which can be managed with conversion to the individual coronary button technique and a bypass procedure using a left subclavian free graft. Both aortocoronary flap and individual coronary button implantation techniques for coronary transfer have excellent mid-term results.

A Study on the Landscape-Oriented Persuasive Language from Naming the Apartment Brand in Korea - Focus on the Analysis of Category and Lexeme - (국내 아파트브랜드 명명(命名)에 담긴 조경지향적 설득언어 - 유형 및 어휘소 분석을 중심으로 -)

  • Rho, Jae-Hyun
    • Journal of the Korean Institute of Landscape Architecture
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    • v.38 no.1
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    • pp.49-63
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    • 2010
  • This study was intended to analyze and interpret the pattern of naming the domestic apartment brand from a semiologic viewpoint in a bid to review the meaning and value of apartment brand, while on the other hand, evaluating the characteristics of persuasive message pursued by current apartment brand in 2010, and consequently, the conclusion of the study is outlined as follows. 1. As a result of analyzing the coinage of branding naming, the words such as combination, joint and blending pattern tended to dominate, which seemed to attempt to represent the variety of values of the housing culture. Brand ideation tends to stress the character symbolism and polysemic message using syllepsis, and the experimental attempt to revive the traditional dwelling concept in a modern sense in a way of combining the archaic word with the Chinese character was found as well. 2. As a result of analyzing the frequency of verbal identity and lexeme of domestic apartments, those frequently used are in order of ville, nature, beauty(美), park, hi, green, palace(宮), nobility and center(tra), which are the lexemes representing the landscape, view, nature and dignity. 3. As a result of identifying the pattern of lexeme using analysis frame based on existing researches such as apartment brand positioning, the most important external core concepts controlling the direction and value of apartment brand are 'environment-orientated' and 'emotion-orientated', and internally, 'function-oriented'. Given the persuasive language expressing the 'environment-oriented' feature and the priority of brand lexeme are garden, park, view and the nature, a landscape-oriented persuasive message is seen to be surging in brand naming. 4. An emotion-oriented persuasive language such as dignity axis having major lexeme represented by palace, nobility, class and a pride axis having major semantic elements represented by human, I and you are used as major value concepts and persuasive language that lead domestic apartment brands to differentiation and upgradation. 5. Among the lexemes focusing on view from environment-oriented standpoint, hi, hill, tower, view, mark, heights are the trend pursued by high-rise apartment aiming at the view such as residential-commercial apartment, and thus the persuasive language focusing on high-rise concept is expected to become the element dominating the trend of apartment brand for the time being.

Discounted Cost Model of Condition-Based Maintenance Regarding Cumulative Damage of Armor Units of Rubble-Mound Breakwaters as a Discrete-Time Stochastic Process (경사제 피복재의 누적피해를 이산시간 확률과정으로 고려한 조건기반 유지관리의 할인비용모형)

  • Lee, Cheol-Eung;Park, Dong-Heon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.29 no.2
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    • pp.109-120
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    • 2017
  • A discounted cost model for preventive maintenance of armor units of rubble-mound breakwaters is mathematically derived by combining the deterioration model based on a discrete-time stochastic process of shock occurrence with the cost model of renewal process together. The discounted cost model of condition-based maintenance proposed in this paper can take into account the nonlinearity of cumulative damage process as well as the discounting effect of cost. By comparing the present results with the previous other results, the verification is carried out satisfactorily. In addition, it is known from the sensitivity analysis on variables related to the model that the more often preventive maintenance should be implemented, the more crucial the level of importance of system is. However, the tendency is shown in reverse as the interest rate is increased. Meanwhile, the present model has been applied to the armor units of rubble-mound breakwaters. The parameters of damage intensity function have been estimated through the time-dependent prediction of the expected cumulative damage level obtained from the sample path method. In particular, it is confirmed that the shock occurrences can be considered to be a discrete-time stochastic process by investigating the effects of uncertainty of the shock occurrences on the expected cumulative damage level with homogeneous Poisson process and doubly stochastic Poisson process that are the continuous-time stochastic processes. It can be also seen that the stochastic process of cumulative damage would depend directly on the design conditions, thus the preventive maintenance would be varied due to those. Finally, the optimal periods and scale for the preventive maintenance of armor units of rubble-mound breakwaters can be quantitatively determined with the failure limits, the levels of importance of structure, and the interest rates.