• Title/Summary/Keyword: Dynamic Data

Search Result 6,570, Processing Time 0.047 seconds

A Dynamic Study of Women's Labor Market Transitions: Career Interruptions and its Determinants (여성의 동태적 노동공급 - 취업연속성과 첫 노동시장 퇴출행태를 중심으로 -)

  • 김영옥
    • Korea journal of population studies
    • /
    • v.25 no.2
    • /
    • pp.5-40
    • /
    • 2002
  • Using detailed data of women's work history, this study analyses the transition process between employment and non-employment over the life history in order to identity individual and structural determinants in the processes. Korean women comprise very heterogeneous groups in terms of work continuity: one group having a continuous work history and another having an interrupted work experience. While 4.0% of total women have stayed in the labor market since leaving school, 17.3% have not worked outside at all and remaining 87.9% have experienced into and out of the labor market at least once. On the average, the cumulated time of employment per woman is 8.2 years and the cumulated time of unemployment is 13.1 years. Thus Korean women work a total of only 38.5% of their whole lifetime after leaving school. We can conclude that the increase of the employment rate of married women in Korea since the 1970s has been due to the increase of the new entrants with short or little working careers into the labor market, not to the increase of women's work continuity on the whole. A women's educational achievement does not seem to be positively related to employment duration, contrary to the suggestion of the human capital theory, Rather, family variables, especially the existence of the child under 6 yens old, is a more significant determining factor for an individual's exit from employment. And there is little difference among different age cohorts which implies little improvement in the employment continuity of younger women. This study also documents the importance of structural variables, such as the type of occupation, as significant determining factors for the hazard rate. Specially women with professional jobs tend to stay longer in the labor market. Therefore, women's entry into more professional occupations is expected to contribute to the continuity of employment. Our results also show that duration-dependence is not spurious. When unobserved heterogeneity is controlled, the negative relation between the rate from employment and the duration of employment does not disappear.

Functional Modifications of Daechung Reservoir Eutrophication by Upper Dam Construction (상류댐 건설에 따른 대청호 부영양화에 대한 기능 변화)

  • Lee, Soon-Cheol;Han, Jung-Ho;An, Kwang-Guk
    • Korean Journal of Ecology and Environment
    • /
    • v.41 no.3
    • /
    • pp.348-359
    • /
    • 2008
  • The objectives of the study were to elucidate functional modifications in relation to hydrological, physico-chemical and ecological aspects in Daechung Reservoir by the upper dam constructions of Youngdam Reservoir and analyze temporal and spatial dynamic patterns using trophic parameters of TN, TP, chlorophyll (CHL), and Secchi depth (SD). Hydrological data such as inflow, precipitation, and water levels before (BDC, 1995$\sim$2000) and after (ADC, 2001$\sim$2006) the dam construction showed that precipitation had greater correlations with inflow volume in the BDC (r=0.964, p=0.002) than in the ADC (r=0.857, p=0.029). This outcome indicates that the upper dam construction influenced the inflow and water level of Daechung Reservoir. One of the greatest changes after the dam construction was decreases of nutrient contents (TN, TP) and increases of algal biomass (as CHL) as the water residence time increases. Values of CHL had greater relations with TP in the ADC (r=0.412, p<0.001) than the BDC (r=0.249, p<0.001), indicating that CHL had greater response at a given phosphorus in the ADC. Thus, algal yield at a given TP (CHL : TP ratios) increased in the ADC, resulting in a greater CHL-TP relations. Long-term interannual TP, TN, SD, and CHL showed greater variations in the riverine zone (RZ) than any other transition (TZ) and lacustrine zones (LZ). This phenomenon was mainly attributed to rapid hydrological response in the riverine zone (RZ) to flow reductions (short water residence time) from the upper dam, resulting in ambient contents of nutrients and light regime along with functional relations of CHL-TP.

Movement of Cold Water Mass in the Northern East China Sea in Summer (하계 동중국해 북부 해역에서 저층 냉수괴의 거동)

  • Jang, Sung-Tae;Lee, Jae-Hak;Kim, Cheol-Ho;Jang, Chan-Joo;Jang, Young-Suk
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
    • /
    • v.16 no.1
    • /
    • pp.1-13
    • /
    • 2011
  • The Yellow Sea Cold Water (YSCW) is formed by cold and dry wind in the previous winter, and is known to spread southward along the central trough of the Yellow Sea in summer. Water characteristics of the YSCW and its movement in the northern East China Sea (ECS) are investigated by analyzing CTD (conductivity-Temperature-Depth) data collected from summertime hydrographic surveys between 2003 and 2009. By water mass analysis, we newly define the North Western Cold Water (NWCW) as a cold water mass observed in the study area. It is characterized by temperature below $13.2^{\circ}C$, salinity of 32.6~33.7 psu, and density (${\sigma}_t$) of 24.7~25.5. The NWCW appears to flow southward at about a speed less than 2 cm/s according to the geostrophic calculation. The newly defined NWCW shows an interannual variation in the range of temperature and occupied area, which is in close relation with the sea surface temperature (SST) over the Yellow Sea and the East China Sea in the previous winter season. The winter SST is determined by winter air temperature, which shows a high correlation with the winter-mean Arctic Oscillation (AO) index. The negative winter-mean AO causes the low winter SST over the Yellow Sea and the East China Sea, resulting in the summertime expansion and lower temperature of the NWCW in the study area. This study shows a dynamic relation among the winter-mean AO index, SST, and NWCW, which helps to predict the movement of NWCW in the northern ECS in summer.

Effects of Leisure Time-Use and Occupational Performance according to the Participation of a Rehabilitation Sports Program for Intellectual Disabilities Residing in a Residential Care Facility (시설 거주 지적장애인들의 재활체육 프로그램 참여에 따른 여가시간 사용과 여가활동 수행에 미치는 영향)

  • Son, Sung-Min;Lee, Kyeong-Lark;Jeon, Byoung-Jin
    • The Journal of Korean society of community based occupational therapy
    • /
    • v.6 no.2
    • /
    • pp.51-59
    • /
    • 2016
  • Objective : The purpose of study is to provide basic information about the effects of leisure time use and leisure activity performance for intellectual disabilities residing in a residential care facility by participating a regular rehabilitation sports program. Methods : Participants were recruited 8 individual with intellectual disability in a residential care facility in Yong-in city and the study period lasted 12 weeks, from september 1 to November 30 in 2015. As a program, participants participated a muscle strengthening exercise using a Gym-ball and a elastic band. In order to analyze leisure time-use, time questionnaire was used every month to analyze total time and exercise frequency. Also, analyze the effects of leisure activity performance, Canadian Occupational Performance Measure(COPM) was used to performance and satisfaction of dynamic leisure activity. Collected data was encoded by item and analyzed with SPSS ver18.0. Descriptive statistics were used for the participants' general information. A non-parametric test (the Friedman test) was used to analyze leisure time-use. A non-parametric test (the Wilcoxon's signed ranked test) was used to analyze to the effects of leisure activity performance. Statistical significance was accepted outside the 95% confidence interval. Results : The results of the total time and the exercise frequency showed significant increase. Also, the results of the performance and the satisfaction showed significant increase. Conclusion : Thus, the participation of the rehabilitation sports program is a vital element to lead to change leisure time use and leisure activity performance for intellectual disabilities residing in a residential care facility. Also, through the providing and the developing a regular rehabilitation sports program systematically, intellectual disabilities residing in a residential care facility have a higher quality of life and satisfaction of the daily routine and life in a residential care facility.

A Study on Netwotk Effect by using System Dynamics Analysis: A Case of Cyworld (시스템 다이내믹스 기법을 이용한 네트워크 효과 분석: 싸이월드 사례)

  • Kim, Ga-Hye;Yang, Hee-Dong
    • Information Systems Review
    • /
    • v.11 no.1
    • /
    • pp.161-179
    • /
    • 2009
  • Nowadays an increasing number of Internet users are running individual websites as Blog or Cyworld. As this type of personal media has a great influence on communication among people, business comes to care about Network Effect, Network Software, and Social Network. For instance, Cyworld created the web service called 'Minihompy' for individual web-logs, and acquired 2.4milion users in 2007. Although many people assumed that the popularity of Minihompy, or Blog would be a passing fad, Cyworld has improved its service, and expanded its Network with various contents. This kind of expansion reflects survival efforts from infinite competitions among ISPs (Internet Service Provider) with focus on enhancing usability to users. However, Cyworld's Network Effect is gradually diminished in these days. Both of low production cost of service vendors and the low searching/conversing costs of users combine to make ISPs hard to keep their market share sustainable. To overcome this lackluster trend, Cyworld has adopted new strategies and try to lock their users in their service. Various efforts to improve the continuance and expansion of Network effect remain unclear and uncertain. If we understand beforehand how a service would improve Network effect, and which service could bring more effect, ISPs can get substantial help in launching their new business strategy. Regardless many diverse ideas to increase their user's duration online ISPs cannot guarantee 'how the new service strategies will end up in profitability. Therefore, this research studies about Network effect of Cyworld's 'Minihompy' using System-Dynamics method which could analyze dynamic relation between users and ISPs. Furthermore, the research aims to predict changes of Network Effect based on the strategy of new service. 'Page View' and 'Duration Time' can be enhanced for the short tenn because they enhance the service functionality. However, these services cannot increase the Network in the long-run. Limitations of this research include that we predict the future merely based on the limited data. We also limit the independent variables over Network Effect only to the following two issues: Increasing the number of users and increasing the Service Functionality. Despite of some limitations, this study perhaps gives some insights to the policy makers or others facing the stiff competition in the network business.

Relationships among CEO Image, Corporate Image and Employment Brand Value in Fashion Industry

  • Ko, Eun-Ju;Taylor, Charles R.;Wagner, Udo;Ji, Hyun-Ah
    • Journal of Global Scholars of Marketing Science
    • /
    • v.18 no.4
    • /
    • pp.307-331
    • /
    • 2008
  • The CEO and the Corporate Image is considered very important in the aspect of marketing. The fact that CEO image itself influences the company or value of the product directly and indirectly has been verified through many cases. Recently, the differentiation of products and services between companies became difficult because the disparity in technique between companies retrenched. As a result, the rate of people who decide to purchase or invest their money based on the corporate image or reputation has been increased. Also in the knowledge society like today, the talented employees are the company's customer and the company's necessity for managing those brains of marketing perspective on how to satisfy and attract the customers is being embossed. The Fashion industry is one of the most value-added industry and in those value-added businesses, the most important factor is the human resources' knowledge power. However the study of the relationships among the CEO image, the corporate image and employment brand value in fashion industry has not been carried out yet. This research considers that dynamic relationship exists among the CEO image, corporate image and employment brand value that affects a company's main goal of pursuing benefits and intends to investigate the relationships of the three concepts. The specific purposes of this study were, 1) to analyze the impact of CEO image on a corporate image, 2) to analyze the impact of corporate image on employment brand value, 3) to analyze the impact of CEO image on employment brand value, 4) to analyze whether corporate image plays a mediating role in the relationship between CEO image and employment brand value or not. A survey design with a structured questionnaire was employed for this research. A convenience sample of 398 subjects was selected from two groups, which are university students majoring in fashion and practitioners working in fashion industry. For the data analysis, descriptive statistic (i.e., frequency, percentage), factor analysis, and multiple regression analysis were used by utilizing SPSS 12.0 for Windows program. The results for this research are as follows, first, the study of the impact of CEO image (i.e., Managerial Competence, Reliability/Leadership, Personal Attractiveness) on corporate image (i.e., Product Image, Corporate Social Responsibility Image, Corporate Cultural Image) brought conclusion that the CEO image generally affected the corporate image in fashion industry. Managerial Competence and Reliability/Leadership affected Product Image, Corporate Social Responsibility Image and Corporate Cultural Image. However, while CEO's Personal Attractiveness affected Product Image and Corporate Social Responsibility Image, it did not affect Corporate Cultural Image. Second, the study of the impact of corporate image on employment brand value brought conclusion that corporate image (i.e., Product Image, Corporate Social Responsibility Image, Corporate Cultural Image) affected employment brand value. Corporate Cultural Image affected employment brand value the most and then the Corporate Social Responsibility Image and Product Image. Third, the study of the impact of CEO image on employment brand value brought conclusion that CEO image (i.e., Managerial Competence, Reliability/Leadership, Personal Attractiveness) affected the employment brand value. CEO's Reliability/Leadership affected the employment brand value the most and then CEO's Personal Attractiveness and CEO's Managerial Competence. Forth, the study examined whether corporate image plays a mediating role in relationship of CEO image and employment brand value and concluded that it does. Corporate image played a full mediating role between CEO's Managerial Competence and employment brand value while it played a partial mediating role between CEO's Reliability/Leadership and CEO's Personal Attractiveness. This study is meaningful in a sense that it examines the relationship among the CEO image, corporate image and employment brand value which has not been carried out yet in fashion industry. It will ultimately contribute to the success of a fashion company by providing useful information of establishing strategies for managing proper the CEO and the corporate image to the fashion company and operating the talented employees.

  • PDF

An Analysis of the Roles of Experience in Information System Continuance (정보시스템의 지속적 사용에서 경험의 역할에 대한 분석)

  • Lee, Woong-Kyu
    • Asia pacific journal of information systems
    • /
    • v.21 no.4
    • /
    • pp.45-62
    • /
    • 2011
  • The notion of information systems (IS) continuance has recently emerged as one of the most important research issues in the field of IS. A great deal of research has been conducted thus far on the basis of theories adapted from various disciplines including consumer behaviors and social psychology, in addition to theories regarding information technology (IT) acceptance. This previous body of knowledge provides a robust research framework that can already account for the determination of IS continuance; however, this research points to other, thus-far-unelucidated determinant factors such as habit, which were not included in traditional IT acceptance frameworks, and also re-emphasizes the importance of emotion-related constructs such as satisfaction in addition to conscious intention with rational beliefs such as usefulness. Experiences should also be considered one of the most important factors determining the characteristics of information system (IS) continuance and the features distinct from those determining IS acceptance, because more experienced users may have more opportunities for IS use, which would allow them more frequent use than would be available to less experienced or non-experienced users. Interestingly, experience has dual features that may contradictorily influence IS use. On one hand, attitudes predicated on direct experience have been shown to predict behavior better than attitudes from indirect experience or without experience; as more information is available, direct experience may render IS use a more salient behavior, and may also make IS use more accessible via memory. Therefore, experience may serve to intensify the relationship between IS use and conscious intention with evaluations, On the other hand, experience may culminate in the formation of habits: greater experience may also imply more frequent performance of the behavior, which may lead to the formation of habits, Hence, like experience, users' activation of an IS may be more dependent on habit-that is, unconscious automatic use without deliberation regarding the IS-and less dependent on conscious intentions, Furthermore, experiences can provide basic information necessary for satisfaction with the use of a specific IS, thus spurring the formation of both conscious intentions and unconscious habits, Whereas IT adoption Is a one-time decision, IS continuance may be a series of users' decisions and evaluations based on satisfaction with IS use. Moreover. habits also cannot be formed without satisfaction, even when a behavior is carried out repeatedly. Thus, experiences also play a critical role in satisfaction, as satisfaction is the consequence of direct experiences of actual behaviors. In particular, emotional experiences such as enjoyment can become as influential on IS use as are utilitarian experiences such as usefulness; this is especially true in light of the modern increase in membership-based hedonic systems - including online games, web-based social network services (SNS), blogs, and portals-all of which attempt to provide users with self-fulfilling value. Therefore, in order to understand more clearly the role of experiences in IS continuance, analysis must be conducted under a research framework that includes intentions, habits, and satisfaction, as experience may not only have duration-based moderating effects on the relationship between both intention and habit and the activation of IS use, but may also have content-based positive effects on satisfaction. This is consistent with the basic assumptions regarding the determining factors in IS continuance as suggested by Oritz de Guinea and Markus: consciousness, emotion, and habit. The principal objective of this study was to explore and assess the effects of experiences in IS continuance, with special consideration given to conscious intentions and unconscious habits, as well as satisfaction. IN service of this goal, along with a review of the relevant literature regarding the effects of experiences and habit on continuous IS use, this study suggested a research model that represents the roles of experience: its moderating role in the relationships of IS continuance with both conscious intention and unconscious habit, and its antecedent role in the development of satisfaction. For the validation of this research model. Korean university student users of 'Cyworld', one of the most influential social network services in South Korea, were surveyed, and the data were analyzed via partial least square (PLS) analysis to assess the implications of this study. In result most hypotheses in our research model were statistically supported with the exception of one. Although one hypothesis was not supported, the study's findings provide us with some important implications. First the role of experience in IS continuance differs from its role in IS acceptance. Second, the use of IS was explained by the dynamic balance between habit and intention. Third, the importance of satisfaction was confirmed from the perspective of IS continuance with experience.

Evaluation of Endothelium-dependent Myocardial Perfusion Reserve in Healthy Smokers; Cold Pressor Test using $H_2^{15}O\;PET$ (흡연자에서 관상동맥 내피세포 의존성 심근 혈류 예비능: $H_2^{15}O\;PET$ 찬물자극 검사에 의한 평가)

  • Hwang, Kyung-Hoon;Lee, Dong-Soo;Lee, Byeong-Il;Lee, Jae-Sung;Lee, Ho-Young;Chung, June-Key;Lee, Myung-Chul
    • The Korean Journal of Nuclear Medicine
    • /
    • v.38 no.1
    • /
    • pp.21-29
    • /
    • 2004
  • Purpose: Much evidence suggests long-term cigarette smoking alters coronary vascular endothelial response. On this study, we applied nonnegative matrix factorization (NMF), an unsupervised learning algorithm, to CO-less $H_2^{15}O-PET$ to investigate coronary endothelial dysfunction caused by smoking noninvasively. Materials and methods: This study enrolled eighteen young male volunteers consisting of 9 smokers $(23.8{\pm}1.1\;yr;\;6.5{\pm}2.5$ pack-years) and 9 nonsmokers $(23.8{\pm}2.9 yr)$. They do not have any cardiovascular risk factor or disease history. Myocardial $H_2^{15}O-PET$ was performed at rest, during cold ($5^{\circ}C$) pressor stimulation and during adenosine infusion. Left ventricular blood pool and myocardium were segmented on dynamic PET data by NMF method. Myocardial blood flow (MBF) was calculated from input and tissue functions by a single compartmental model with correction of partial volume and spillover effects. Results: There were no significant difference in resting MBF between the two groups (Smokers: 1.43 0.41 ml/g/min and non-smokers: $1.37{\pm}0.41$ ml/g/min p=NS). during cold pressor stimulation, MBF in smokers was significantly lower than 4hat in non-smokers ($1.25{\pm}0.34$ ml/g/min vs $1.59{\pm}0.29$ ml/gmin; p=0.019). The difference in the ratio of cold pressor MBF to resting MBF between the two groups was also significant (p=0.024; $90{\pm}24%$ in smokers and $122{\pm}28%$ in non-smokers.). During adenosine infusion, however, hyperemic MBF did not differ significantly between smokers and non-smokers ($5.81{\pm}1.99$ ml/g/min vs $5.11{\pm}1.31$ ml/g/min ; p=NS). Conclusion: in smokers, MBF during cold pressor stimulation was significantly lower compared wi4h nonsmokers, reflecting smoking-Induced endothelial dysfunction. However, there was no significant difference in MBF during adenosine-induced hyperemia between the two groups.

Usefulness of $^{99m}Tc$-labeled RBC Scan and SPECT in the Diagnosis of Head and Neck Hemangiomas (두경부 혈관종 진단시 $^{99m}Tc$-RBC Scan and SPECT 검사의 유용성)

  • Oh, Shin-Hyun;Roh, Dong-Wook;Ahn, Sha-Ron;Park, Hoon-Hee;Lee, Seung-Jae;Kang, Chun-Goo;Kim, Jae-Sam;Lee, Chang-Ho
    • The Korean Journal of Nuclear Medicine Technology
    • /
    • v.12 no.1
    • /
    • pp.39-43
    • /
    • 2008
  • Purpose: There are various methods to diagnose hemangioma, such as ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI) and nuclear medicine. However, by development of SPECT imaging, the blood-pool scan using $^{99m}Tc$-labeled red blood cell has been used, because it was non-invasive and the most economical method. Therefore, in this study, we proposed that the usefulness of $^{99m}Tc$-RBC scan and SPECT of the head and neck to diagnose unlocated hemangiomas. Materials and Methods: $^{99m}Tc$-RBC scan and SPECT was performed on 6 patients with doubtful hemangioma (4 person, head; 1 person, neck; 1 person, another). We labeled radiopharmaceutical using modified in vivo method and then, centrifuged it to remove plasma. After a bolus injection of tracer, dynamic perfusion flow images were acquired. Then, anterior, posterior, both lateral static blood-pool images were obtained as early and 4 hours delayed. SPECT was progressed 64 projections per 30 seconds. Each image was interpreted by physicians, Nuclear medicine specialist, and technologist blinded to patient's data. Results: In 5 patients of all the radioactivity of doubtful site didn't change in flow images, but, in blood-pool, delayed and SPECT images, it was increased. So, it was a typical hemangioma finding. The size of lesion was over 2 cm, and it could discriminate as comparing to the delayed and SPECT imaging. On the other hand, in 1 patient, the radioactivity was increased in blood-pool images, but, not in delayed and SPECT images, so, it was proved no hemangioma. Conclusion: Using $^{99m}Tc$-RBC Scan and SPECT, we could diagnose the hemangiomas in head and neck, as well as, liver, more non-invasive, economical, and easy. Therefore, it considered that $^{99m}Tc$-RBC scan and SPECT would offer more useful information for diagnosis of hemangioma, rather than otherimaging such as US, CT, MRI.

  • PDF

Clinical Usefulness of Arterial Spin Labeling Perfusion MR Imaging in Acute Ischemic Stroke (급성 허혈성 뇌경색 환자에서 동맥스핀표지 관류자기공명영상의 유용성)

  • Oh, Keun-Taek;Jung, Hong-Ryang;Lim, Cheong-Hwan;Cho, Young-Ki;Ha, Bon-Chul;Hong, Doung-Hee
    • Journal of radiological science and technology
    • /
    • v.34 no.4
    • /
    • pp.323-331
    • /
    • 2011
  • We evaluated clinical usefulness of Arterial spin labeling perfusion MR imaging on the acute ischemic cerebral infarction patients through this study. We compared 22 patients who were done with DSC imaging and ASL imaging in admitted emergency room with acute ischemic cerebral infarction, with 36 normal comparison persons (DSC image on 21persons, ASL images on 15persons). Siemens Magnetom Verio 3.0T with 12 channel head coil was used for this study. DSC image obtained 4 maps(rCBV, rCBF, rMTT, TTP) through post-processing. For qualitative analysis we compared the area of lesion macro-diagonal with the size of diffusion weighted MR image for rMTT, TTP, rCBF, rCBV, ASL maps. For Quantitative analysis we analyzed significant correlations between less than 3 cm infarction group and normal comparison group using mean relative value of flowing image with Mann-Whitney U test. TTP(95.5%) and rCBF(95.5%) maps showed high recognition rate in qualitative analysis for >3cm infarction group. The rCBF and rCBV map tests were highly related with final stage stroke areas. Mean relative value of infarction group showed a significant correlations in quantitative analysis(p<0.05). As a conclusion, arterial spin labeling image showed high lesion recognition rate in the >3cm infarction group. Mean relative values in quantitative evaluation were used for reference data. If we do more sustainable researches, ASL image will be useful for an early diagnosis of cerebral infarction, determination of the range of ischemic pneumbra and effective treatments.