• Korea journal of population studies
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• v.35 no.2
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• pp.29-53
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• 2012

This research studies how women's hourly wages affect childbearing using data from the National Longitudinal Survey of Youth. The results of discrete time hazard model show that the relationship between women's hourly wage and fertility is dynamic. Overall relationship looks negative, but they are not consistent across education levels. Women who have a high school diploma or less have a tendency to decrease childbearing when their wages increase. But women who have some college experience or a college degree are likely to have children when their wages increase. It means that only for highly educated women who are likely to be in high paying decent jobs, the rise of income can be used as a resource for reconciling the mother's and worker's roles. Or, for less educated women who are likely to be in the low paying jobs, the rise of income is not large enough to lessen role incompatibility.

• Knowledge Management Research
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• v.21 no.4
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• pp.265-285
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• 2020

The inbound tourism market is recognized as a vital sector of the tourism industry today, but it is highly volatile due to each country's economic, social, and cultural variables. The causes of volatility vary according to the inbound country, and we intend to revitalize the stabilized tourism industry by minimizing risks. In this study, the portfolio theory was applied to derive the optimal combination for each country to achieve the minimum risk level's maximum growth rate. The number of inbound travelers and the average expenditure per person was simultaneously applied. As a result of the analysis, the best mix by country based on the number of inbound travelers was the UK, the United States, Germany, China, and Japan. Based on average spending, each country's best combinations were Thailand, Middle East, Singapore, Japan, Russia, Hong Kong, and Germany. It is expected to be able to establish a plan to operate the Korean inbound tourism market strategically.

• Journal of the Korea Convergence Society
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• v.12 no.1
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• pp.267-274
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• 2021

This paper examines the impact of the Basic Pension scheme in terms of poverty reduction and income distribution among elderly households by focusing on the differences in the household type. It compares the data before (2013) and after (2016, 2019) the introduction of Basic Pension by using Household Income and Expenditure Survey data. Empirical analyses indicate that, first, the overall income and the public income transfer of the elderly households increased during the period compared. Second, the poverty rate was considerably higher for the elderly living alone than for other household types. The government policy led to poverty-reduction for all types of elderly households, wherein the effect was most profound in the case of elderly living with spouse. Third, income distribution improved for all types of elderly households, though maximum margin was observed in the case of the elderly living alone. Fourth, according to the multivariate logit regression, the Basic Pension had a positive impact on reducing the risk of poverty (defined as below 40% of median income) among the elderly households.

• Journal of Korea Water Resources Association
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• v.54 no.3
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• pp.157-166
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• 2021

Forecasting dam inflow based on high reliability is required for efficient dam operation. In this study, deep learning technique, which is one of the data-driven methods and has been used in many fields of research, was manipulated to predict the dam inflow. The Long Short-Term Memory deep learning with Sequence-to-Sequence model (LSTM-s2s), which provides high performance in predicting time-series data, was applied for forecasting inflow of Soyang River dam. Various statistical metrics or evaluation indicators, including correlation coefficient (CC), Nash-Sutcliffe efficiency coefficient (NSE), percent bias (PBIAS), and error in peak value (PE), were used to evaluate the predictive performance of the model. The result of this study presented that the LSTM-s2s model showed high accuracy in the prediction of dam inflow and also provided good performance for runoff event based runoff prediction. It was found that the deep learning based approach could be used for efficient dam operation for water resource management during wet and dry seasons.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.3
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• pp.287-295
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• 2023

The collapse of bridges due to earthquakes results in many casualties and property damages. Thus, accurate prediction and preparation are required for the behavior of bridges during earthquakes. In particular, columns play an important role in the seismic behavior of bridges. The risk of collapse due to an earthquake increases when there is a problem of the insufficient lap splice in the column. In this study, to analyze the characteristics of the lap splice in the column, a numerical model was defined for the insufficient lap-spliced columns and verified using experimental data. The developed column model was applied to a commonly used RC slab bridge. Nonlinear static analysis for the column was performed to evaluate the change in the performance of the column according to the lap-spliced length. In addition, this study assessed the effect of the lap-spliced length on the seismic fragility analysis.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.65-65
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• 2020

기후변화에 관한 IPCC 제5차 평가보고서에 따르면 최근 나타난 기후 관련 극한 현상인 폭염, 홍수, 가뭄 등의 영향에 대해 생태계가 현재의 기후 변동성에 상당히 취약하게 반응하며, 기후변화를 위험에 초점을 맞추어 평가함으로써 대응책을 마련해야 한다고 강조하였다. 기후변화에 따라 강수량 패턴과 수문학적 시스템이 변하면서 수자원의 미치는 영향과 취약성, 적응에 대한 연구의 필요성이 요구되고 있으며, 농업용수를 비롯한 수자원 관리 기술 및 적응역량을 강화하는 것이 필요하다. 수리답 면적에 대한 농업용수 공급의 61%를 차지하는 농업용 저수지의 경우 과거 10년 한발빈도로 설계되어 최근의 연속적인 가뭄 사상으로 인한 낮은 저수율을 나타내어 가용 수자원의 부족이 발생하였다. 이에 따라 저수지 설계 당시와 상이한 환경 및 기후의 변화로 농업용수 공급체계의 상황변화에 따른 용수공급능력 및 이수안전도의 재평가가 요구된다. 일부 가뭄대책지구에 대하여 기후변화에 따른 현장여건 변화 (논면적, 영농패턴, 작부시기 등)를 반영한 이수안전도를 재평가함으로써 농업용 저수지의 용수공급에 대한 정량적 분석이 수행되었다. 저수지별로 기후변화 및 현장여건 변화에 따른 영향이 다르므로 전국 농업용 저수지를 대상으로 확대, 적용하기 위해서는 저수지 특성을 분석하여 비슷한 패턴을 갖는 저수지로 유형화하기 위한 작업이 필요하다. 본 연구에서는 농어촌공사 관할 3,394개의 농업용 저수지를 대상으로 지역에 따라 인자별 군집분석을 실시하여 국내 농업용 저수지의 이수안전도 변화에 따른 물 공급 잠재능을 재평가하고자 한다. 본 연구의 결과는 기후와 영농방식, 지역별 특성 등 상호간의 관계를 고려한 농업용수관리와 유사한 특성을 갖는 지역계획의 추진단위를 결정하거나 지역간의 비교우위를 고려한 한해 대책 등과 같은 농촌지역개발계획 등에 활용할 수 있을 것으로 기대한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.238-238
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• 2022

합천댐의 건설 이후, 댐직하류 구간에서는 10년 동안의 방류량 감소와 기후변화로 인한 강우패턴의 변화로 하도식생의 활착이 발생하여 식생이 증식하고 밀도가 점차 증가하고 있다. 식생밀도의 증가는 흐름에 대한 항력을 증가시켜 유속을 감소시키고 수심을 증가시킨다. 이는 통수능 저하를 초래하며, 홍수 시 수위증가에 따른 홍수범람의 위험성 증가시킨다. 따라서 식생영향에 대한 심화적인 이해를 제고하여 적절한 식생관리대책을 구축할 필요가 있다. 본 연구에서는 이러한 필요성에 맞추어 식생대 영향에 따른 흐름의 변화를 예측모의하여 흐름과 식생대의 상호작용에 대한 분석을 수행하였다. 이를 위해 2차원 흐름모형인 Nays2D를 이용하여 합천댐 직하류 구간을 대상으로 식생밀도의 변화에 따른 흐름의 변화를 부등류를 기반으로 모의하였다. 상류단의 경계조건은 162.99 m³/s(실운영 방류량), 995 m³/s(2년빈도 댐 조절 방류량), 2670 m³/s(100년빈도 댐 조절 방류량)로 3개의 유량으로 구분하여 모의하였다. 식생의 특성은 현장조사를 통해 밀도를 산정하여 수치모의에 적용하였다. 식생밀도는 4가지로 구분하여 모의시나리오를 구축하였으며 현장조사를 통해 산정된 2021년도 식생밀도를 기준으로 식생밀도를 증감하여 수치모의를 수행하였다. 수치모의 조건은 2021년 식생현황, 식생개선, 식생존치, 전벌채로서 식생개선의 경우, 2021년 식생밀도의 0.5배로, 식생존치의 경우, 식생밀도를 2배로 적용하였다. 전벌채는 식생이 없는 것으로 가정하였다. 수치모의 결과, 식생개선이 2021년 식생현황과 식생존치보다 상대적으로 수심이 낮게 나타났다. 식생을 전벌채한 경우, 식생이 존재하는 조건보다 수심이 낮고 유속이 빠르게 나타났으며 특히, 만곡부의 외측에서는 2차류의 발달로 흐름이 집중되었다. 이를 통해 식생개선의 경우, 식생현황과 식생존치보다 홍수범람의 가능성이 적을 것으로 판단되며 전벌채의 경우, 만곡부 외측에서 2차류 발달에 의한 세굴을 야기하여 제방의 안정성에 영향을 줄 것으로 예측된다. 본 연구는 댐 직하류에 식생대 밀도변화가 흐름변화에 미치는 영향을 분석한 수치모의 사례로서 이는 추후 식생을 고려하는 하천관리방안을 수립 시, 식생관리방법에 대한 근거자료로 활용될 수 있을 것으로 기대된다.

• Environmental and Resource Economics Review
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• v.33 no.2
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• pp.179-201
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• 2024

In introducing emissions trading schemes, many countries start with a high level of free allocation to reduce the sudden cost burden on companies and increase acceptance of the policy. The free allocation is then gradually reduced, considering the risks of carbon leakage. This aligns with the "polluter pays" principle and is often considered one of the elements of an advanced emissions trading scheme. In this context, this study uses a simple emissions trading market model to show that decreasing the free allocation rate may not be desirable if the emissions market is not perfectly competitive. In particular, by identifying the existence of a free allocation rate at which the cost inefficiency is minimized, this study demonstrates that having a low level of free allocation does not necessarily imply the improvement of the emissions trading scheme.

• Korean Journal of Psychosomatic Medicine
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• v.22 no.1
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• pp.3-12
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• 2014

Objectives : We aimed to explore the relationship among fatigue and perceived stress, depressive mood in the working population. We also examined associations with demographic and life style factors and investigated the effect of individual coping skills on these associations. Methods : Fatigue Severity Scale(FSS), Perceived Stress Scale(PSS), Brief Encounter Psychosocial Instrument - Korean version(BEPSI-K), Beck Depression Inventory(BDI), Stress Coping Skill Questionnaire were administered to 621 civil servants. All of above and other demographic factors are self-administered questionnaire survey and this study is cross sectional. Results : Mean FSS score was 3.04 which was lower than 3.22, the severity cut off score. FSS, PSS, BEPSI-K, BDI were all higher in female. Subjects with active coping skills showed relatively low fatigue, perceived stress, depressive mood than those with passive coping skills. Logistic regression analyses indicated that the PSS, BDI, BEPSI-K in working population increase the risk of fatigue and regular exercise lowers the risk. Conclusions : Adults who were afflicted by stress, experienced depressive mood or were physically inactive were at much higher risk of feeling fatigue. Since no other large data sets are available for fatigue, the results from this study could serve a very useful purpose, to furnish a basis for comparison with future research results based on more complete data.

• Journal of Ginseng Culture
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• v.1
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• pp.93-109
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• 2019

This study aims to look at the process of ginseng being removed from the Western pharmacopoeia in the 19th century, experiencing a crisis as an export product in the America in the 20th century, and eventually settling in the U.S. society and the military as a dietary supplement in the 21th century. In this process, the legislation of provided a bridgehead for ginseng and other botanical dietary supplements to enter the U.S. market. As a result, ginseng could be re-listed in the U.S. pharmacopoeia as a dietary supplement. However, this did not mean a complete soft landing of ginseng and other botanical dietary supplements in the America. The U.S. medical community, which has been afraid of the indiscriminate spread of botanical dietary supplements, has constantly raised "the risk-discourse" and expressed concerns over the use and abuse of botanical dietary supplements that have not been scientifically verified. This involved not only the fundamental problems caused by the lax verification process of , but also a new atmosphere in the U.S. where the public sought information about botanical dietary supplements rather than seeking professional clinicians related to their health. Against this situation, "the advocate-discourse" suggested by dietary supplement manufacturers and the people in charge of botanical products seemed rather relaxed. As consumers are taking this side, the advocates had only to stress that botanical dietary supplements have been used worldwide for a long time without any problems and were made from 'natural' materials. The fact that ginseng and other botanical dietary supplements were able to advance to the U.S. Military's dietary supplement manual, which is strict in controlling food, seems to have jumped on the bandwagon of this atmosphere in the U.S. Society. In the early U.S. dietary supplement manual reviewed in this paper, ginseng was the most detailed among many botanical dietary supplements. Although there are some 'safety concerns' that still exist in the civilian society, but there are also certainly good scientific explanations for the efficacy and references to the popularity and influence of ginseng in the American society. Given this, the U.S. society and military's interest in ginseng as a dietary supplement seem quite high.