• Asian-Australasian Journal of Animal Sciences
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• v.19 no.4
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• pp.549-553
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• 2006

In this study, the effects of granite-grit offered free-choice on voluntary intakes of grit and subsequently on some morphologic traits of the digestive tract and performance of broilers were investigated. A total of 240 7d-old male broiler chicks (Ross 308) were allotted randomly to 10 floor pens supplied with wood shavings. The experiment lasted for 42 days. There were 2 dietary treatments, each consisting of 5 replicates. Each replicate consisted of 24 birds kept in an experimental unit with a floor size of $2{\times}2m$. Dietary treatments consisted of control (C) in which broilers were fed standard broiler rations, and acid insoluble granite-grit choice (AIGG) in which broilers were fed standard broiler rations and grit in separate troughs. Mean amounts consumed varied quite widely from week to week, but on average broilers ate 3.41 g per d per bird during the experimental period. Birds had a higher voluntary intake of granite-grit at an early age (7 to 21 d of age) than later (22 to 42 d of age). The voluntary intake of granite-grit of AIGG broilers increased (p<0.05) from 2.7 g/day at 7-14 d to 4.4 g at 15-21 d of age, and then it decreased to 3.4, 3.2 and 3.4 g/day between 22-28, 29-35 and 36-42 d of age, respectively. This level of grit intake increased (p<0.05) weights of empty gizzard (0.97 vs. 1.30 g), edible inner organs (3.51 vs. 3.69 g), and length of gut (8.86 vs. 9.01 cm) as a proportion of body weight and the content of insoluble ash (8.4 vs. 42.2 g/kg) in the faeces compared to the control group. Feeding free-choice grit had little or no effect on final live weights (2,542 vs. 2,543 g), daily gains (69 vs. 69 g), carcass weights (1,924 vs. 1,911), dressing percentages (75.6% vs. 75.1%) and feed efficiencies (1.69 vs. 1.66). Birds given grit did not gain more weight than those not given grit but they tended to have (p<0.07) lower feed intake (116.7 vs. 114.5 g), and consequently lower protein and energy intake. In conclusion, the granite-grit consumed voluntarily by broilers increased gut length and empty gizzard weight without affecting growth performance of broilers. Thus, it can be assumed that the voluntary consumption of granite-grit was too low to affect performance.

• Journal of Families and Better Life
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• v.31 no.5
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• pp.79-95
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• 2013

This study is aimed at exploring the experience of couples choosing not to have children after marriage. To identify the motives for voluntary childlessness and social perceptions, a qualitative research method was used for analysis. After in-depth interviews were conducted with 15 childless couples who had agreed to participate in the research, 15 meaning units, 5 categories, and 3 topics were established. The research findings were categorized as follows: 'the motives for being childless', 'the surrounding response and coping response', and 'the expectation of a childless family's society.' The research participants argued that families without children should be fully accepted in the changing society, with the hope that their childlessness would be respected. The significance of this study is that it focused on the perceptions of families and society, while steering away from personal views on the meaning of a life absent of children. Based on the perception that childlessness is not only a personal matter but also a social issue, this study clearly showed a variety of reactions to childless couples, such as the labeling of them as eccentric people and disapproval of them. Furthermore, this study has elaborated on the personal experience of childless couples by clearly indicating their desires to seek government support and compensation.

• Journal of the Chungcheong Mathematical Society
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• v.33 no.2
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• pp.293-300
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• 2020

In this paper we study an optimal consumption, investment and retirement time choice problem of an investor who receives labor income before her voluntary retirement. And we assume that there is a negative wealth constraint which is a general version of borrowing constraint. Using convex-duality method, we provide the closed-form solutions of the optimization problem.

• The Journal of Information Systems
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• v.17 no.4
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• pp.99-127
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• 2008

E-learning becomes an important part of education these days in Korea. Students had no choice but to accept the e-learning when the e-learning was used as a supplementary learning tool within a traditional class or a stand-alone distance education. This study focuses on the students' intention of e-learning acceptance for voluntary studies. In voluntary study, students have the rights to adopt the e-learning or not for their personal study. We used individual characteristics as the external variables of TAM to explain user acceptance of e-learning for voluntary studies and examined the effect of individual characteristics on user's beliefs. Research model and nine hypotheses were set up to identify the relationships among these variables based on investigations of previous researches. The theoretical model is tested with questionnaires from 420 users who accept e-learning for voluntary studies. We tested the measurement and research models by applying a structural equation modeling(SEM) approach, using the AMOS 5.0. Overall, the results provided support for the model as explaining acceptance of an e-learning system. Most path coefficients in the research model were found statistically significant. The results showed usefulness and enjoyment and subject norm were the factors affecting attitude of students using e-learning. In addition, usefulness and subject norm were the factors affecting intention of students using e-learning. The results show innovation and self-efficacy have a significant impact on user's perception of ease of use. Self-efficacy also have significant effects on user's perception of usefulness.

• Journal of the Korean Regional Science Association
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• v.32 no.1
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• pp.83-103
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• 2016

This study aims to analyze the determinants of residential location choice for the inter-urban migrants in the Seoul metropolitan area. In doing so, we have built a discrete choice model, using household sample data from the 2010 Korea Population and Housing Census. We classified households, which made a intra-urban movement during the last five years, into four groups: 1) movers from Seoul (central city) to Gyunggi-Incheon (suburban), 2) movers from Gyunggi-Incheon to Seoul, 3) Intra-Seoul movers, and 4) intra-Gyunggi-Incheon movers. The analysis findings can be summarized as follows. First, significant differences in the determinants of residential location choice were found among different types of movers. Second, movers from Gyunggi- Incheon to Seoul were likely to choose small housings with fewer rooms, indicating that their housing choices were forced rather than voluntary due to high housing prices in Seoul. Third, all types of movers have a high preference for the neighborhood with a good accessibility by public transit including subway. Lastly, neighborhood amenity was also an important attracting factors for the intra-urban migrants in Seoul.

• Journal of the Korean Institute of Rural Architecture
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• v.25 no.3
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• pp.1-8
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• 2023

This study aims to analyze the trend of changes in the elderly living arrangement over the past 20 years and the reasons why the elderly choose these changes. The subjects of the survey were households aged 65 years or older in Korea. Data from the survey of Ministry of Health and Welfare conducted in 2004, 2014, 2020 were used for the analysis. The result of analysis was as follows; First, since 2000, the number of elderly households living with their children has been rapidly decreasing, while the number of elderly couple households and single elderly households is gradually increasing. Second, elderly living alone appeared more in rural areas, women, older people, and elderly with low education. They are in a vulnerable position that needs help. Therefore, welfare policies for the elderly should be focused on elderly single households. Finally the reason for choosing elderly single household in 2020 was that the voluntary choice by the individual accounted for a much higher rate than the unintentional choice by the children. In addition, the life satisfaction of the elderly who arbitrarily selected the living arrangement was higher than that of the elderly who deliberately chose the living arrangement.

• Journal of Labour Economics
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• v.30 no.1
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• pp.109-137
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• 2007

One of the key features of the Korean labor market is that, even though the central axis of employment has shifted from manufacturing sector to service sector, the ratio of part-time work is very low. Its major reasons are low wage rate, insufficient fringe benefits including social insurance, and deficient job security, even though part-time work has positive characteristics. This study examines whether part-time work would be a decent one and an alternative to full-time work by answering two questions: one is who chooses part-time work and another is whether part-time work is satisfactory. Analyses of 3,971 wage workers in the 8th wave of the Korea Labor and Income Panel Survey reveal that, as expected, part-time work is prevalent among the young, married women, and the old supporting the results from previous studies and that choosing part-time work on one's initiatives has a significant positive effect on job satisfaction for women while it is not for men. Form the result, it can be concluded that part-time work can be an appropriate alternative for full-time work if one chooses it voluntarily.

• Environmental and Resource Economics Review
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• v.16 no.3
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• pp.683-699
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• 2007

This study applied the choice experiment (CE) method to measure values of statistical lives from multi-attributed mortality risk reduction choices. The four characteristics of mortality risk (i.e. cause of death, voluntariness of mortality risk, timing of death, magnitude of mortality risk reduction) are utilized to design the alternatives of choice sets. The estimation results for the multinomial logit model show that individuals are willing to pay 27,930 won per year for a change from the status quo to a $\frac{1}{100}$ mortality risk reduction for 10 years, 116,773 won per year for mortality risk reduction associated with adults, 97,682 won per year for voluntary mortality risk reduction, 77,234 won per year for involuntary mortality risk reduction. There were several estimates of VSL related to different attributes of mortality risk. The mean VSLs of infant/child/young adult ranged from 1,165 million won to 1,367 million won. The mean VSLs ranged from 1,631 million won to 1,833 million won for adult, and were between 1,128 million won and 1,330 million won for old person.

• Journal of Labour Economics
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• v.41 no.1
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• pp.39-81
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• 2018

This study focuses on whether non-standard workers are matched by voluntary contract with employers in the labor market and analyzes the factors of involuntary choice of non-standard employees that are diverse by firm size. For the analysis I consider non-standard employees as either voluntary or involuntary according to the push/pull theory based on labor mobility. The Economic Activity Census Added Survey data 2016 show that the proportion of involuntary non-standard employees is greater than voluntary ones as the firm size is smaller. As a result of the analysis, involuntary non-standard employees are not significantly discriminated from voluntary non-standard employees in large firms. However, in small and medium-sized firms and micro small-sized firms, workers are more likely to be involuntarily non-standard if they are older or less educated. In addition, they are more likely to be employed involuntarily in micro small-sized firms than in small and medium-sized firms. Therefore, we should take into account the mismatching problems of compensation, specialty, and career in order to establish policies on non-standard workers. In addition to the financial support for small and medium-sized and micro small-sized firms, it is necessary to provide workers with job information that matches their job skills and career experiences.

• Journal of Acupuncture Research
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• v.20 no.4
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• pp.170-179
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• 2003

목적 : 침(鍼)은 정신이상 및 약물중독과 같은 많은 기능상의 장애질환을 치료, 조정하는데 널리 쓰이고 있으며, 중추신경계에서 생화학적인 균형을 유지하는데 기여한다고 밝혀져 있다. 동물 연구에서 코카인의 강화 및 민감화 특성과 중추의 도파민 활성과의 관련 가능성이 높아지고 있다. 본 연구에서는 약물중독 치료에 이용할 수 있는 침의 효과를 규명하기 위하여 침자극 후 급성 코카인 투여에 의한 도파민 유리 및 자발적 코카인 섭취량에 미치는 침자극의 효과를 측정하였다. 방법 : 웅성 SD 쥐에 코카인 (1mg/kg, i.v.)의 주사 직전 양측의 신문혈(HT7)을 1분간 침자극 한 후, 측핵내 세포외액의 도파민 및 대사산물의 함량변화를 미세투석법을 이용하여 HPLC로 분석하였다. 침자극 후 two-bottle, free choice protocol을 이용하여 자발적 코카인 섭취량의 변화를 관찰하였다. 별도의 쥐를 이용하여 1회 동량의 코카인 정맥주사하고 2주간의 철회를 거친 다음 two-bottle, free choice protocol을 실시하여 자발적 코카인 섭취량과 급성 코카인 투여 후 측핵 중 도파민유리증가율 사이의 상관관계를 조사하였다. 결과 : 신문혈(HT7) 자침이 코카인 1회 주사 후에 유도된 도파민 증가를 대조혈(내관혈(PC6), 또는 꼬리)에 비해 유의하게 억제하였으며 two-bottle choice protocol에 의한 동물의 자발적 코카인 섭취량을 억제하였다. 아울러 자발적 코카인 섭취량과 급성 코카인 투여 후 측핵 중 도파민유리증가율 사이에는 상관관계가 있었다. 결론 : 본 실험결과 침자극에 의해 자발적 코카인 섭취량이 억제되는 것은 측핵에서의 도파민 유리억제에 의해 중개되는 것으로 보여지므로 침자극은 코카인중독과 같은 약물의 중독치료에 이용될 수 있을 것으로 사료된다.