• Journal of the Microelectronics and Packaging Society
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• v.8 no.4
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• pp.25-33
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• 2001

Sn-3.5Ag-xBi alloys with five different levels of Bi (0, 2.5, 4.8, 7.5, 10 wt%) were prepared for evaluating creep properties. Cast alloys were roiled and heat treated to provide stable microstructures during the subsequent creep tests, which were conducted under constant load using dog-bone specimens. For the Bi containing alloys, creep strength showed the maximum around 2.5 wt%Bi and tended to decrease with increasing Bi content. The stress exponent of the alloy was around 4, suggesting typical dislocation creep, but the exponent was 2 for the 10 wt%Bi alloy, suggesting creep assisted by grain boundary Sliding. For the Bi containing alloys, the brittle fracture mode appeared showing small amount of reduction of area, while the ductile fracture mode was true for the Bi free alloy. Microstructural examination of ruptured specimens showed cavitations on grain boundaries normal to the load axis, and a significant of grain boundary sliding for the Bi containing alloys.

• Korea journal of population studies
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• v.29 no.1
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• pp.241-268
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• 2006

This study aim to examine the optimum population in Korea, which has the lowest fertility rate in the world. This study has significance because this rapid decline in the fertility rate is expected to bring the decrease of the population and unbalance in the population composition in Korea. From the social welfare perspective, the optimum population is guided by maximization of the social welfare level per person or the social welfare level in a society. The optimum population can be defined as follows: The proportion of older adults 65 and over is 15-17%, the proportion of work force is 64-69%, the index of aging is 72-104. Within the current population and population composition, the optimum population is estimated as 4.85-4.95 million. These findings imply that we need to remove causes of low fertility rate and prepare for policies encouraging immigration of labor force from foreign countries. In addition, policies and programs where children can be grown up in good environments and women and older adults can participate in labor force should be established.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.262-267
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• 2016

In this study, we present an excellent approach for easily and uniformly immobilizing Pt, Au and bimetallic PtAu nanoparticles (NPs) on a multi-walled carbon nanotube (MWNT)-coated layer through dry plasma reduction. The NPs are stably and uniformly immobilized on the surface of MWNTs and the nanohybrid materials are applied to counter electrode (CE) of dye-sensitized solar cells (DSCs). The electrochemical properties of CEs are examined through cyclic voltammogram, electrochemical impedance spectroscopy, and Tafel measurements. As a result, both electrochemical catalytic activity and electrical conductivity are highest for PtAu/MWNT electrode. The DSC employing PtAu/MWNT CE exhibits power conversion efficiency of 7.9%. The efficiency is better than those of devices with MWNT (2.6%), AuNP/MWNT (2.7%) and PtNP/MWNT (7.5%) CEs.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.311-316
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• 2015

하천 유사량 자료는 하천의 이 치수 목적으로 활용할 수 있는 기본 자료중 하나로서 하상변동 예측, 저수지 퇴사량 추정, 하도 계획과 설계, 유사조절 계획 수립 및 기타 구조물 등의 영향 평가 등 다양하게 활용할 수 있다. 정도 높은 유사량 자료를 측정하기 위해서는 현장측정부터 분석까지 정확한 과정과 세밀한 준비가 필요하다. 본 연구에서는 정도 높은 유사량 자료를 생산하기 위하여 국가 유사량 관측망 중 19개 지점(율극, 점촌, 일선교, 구미, 왜관, 선산, 죽고, 진동, 개진2, 정암, 회덕, 마륵, 나주, 학교, 남평, 영수, 선암, 구례2, 죽곡, 용서, 곡성)에 대하여 부유사량 특성분석을 수행하고 이를 반영하여 유량-부유사량관계곡선식을 개발하였다. 유사량 측정과정은 사전조사, 현장측정, 실험실분석, 모형적용 단계를 거친다. 사전조사 단계에서는 현장에 대한 현장안전, 지점특성 등의 현장관련 정보를 수집하여 현장측정 계획을 수립한다. 현장측정 단계에서는 사전에 유량측정 자료를 이용하여 측선을 나누는 등유량법과 등간격법을 사용하였으며, ISO 기준 이상의 5~8개 측선을 나누어 측정하였다. 측정장비는 D-74 부유사 채취기를 이용하여 왕복수심적분법으로 부유사량 샘플을 채취 하였다. 실험실분석은 유량조사사업단 유사분석센터에서 채취 시료에 대한 농도, 레이저 회절법을 이용한 부유사입도분석, 하상토분석(체분석)을 실시하였다. 또한, 유량-부유사량 농도 변화양상과 부유사량 특성분석을 이용한 부유사량 측정결과를 평가하였고 각 지점의 부유사량특성을 잘 나타낼 수 있는 지수식($Q_{ss}=aQ^b$)을 이용하여 유량-부유사량관 계곡선식을 개발하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.263-263
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• 2016

기후변화 등에 따른 가뭄위험을 평가하기 위한 다양한 방법이 연구되어 왔으며, 기상학적인 가뭄이나 생물학적인 가뭄 등으로 정의되는 가뭄지수들이 개발되어졌다. 그러나 궁극적으로 가뭄의 판정은 수원으로부터 더 이상의 용수를 공급할 수 없는 상황에 처해졌을 때 비로소 결정되는 것이므로, 수원공의 가뭄위험에 대한 평가가 우선적일 것으로 판단된다. 본 연구에서는 수도권의 생공용수 공급을 책임지고 있다고 해도 과언이 아닌 다목적댐인 소양강댐과 충주댐의 가뭄위험을 평가하기 위하여 월강우량 자료로부터 특정시기의 저수율을 예측할 수 있는 방법을 개발하도록 하였다. 월강우량 변화에 따른 저수율의 변화양상을 예측하기 위하여 저수지 유입량과 방류량에 따른 물수지 분석이 정교하게 이루어져야 하지만, 실질적으로 상류에 또 다른 댐이 존재하는 상황에서 유입량을 정확하게 예측하는 것도 어렵지만 수시로 상황에 따라 이루어지는 방류량을 적절히 예측하는 것은 거의 불가능하므로, 물수지 분석에 의한 저수율 예측은 어느 정도의 불확실성을 가질수밖에 없을 것으로 판단되어 댐 관리관행에 따라 나타나는 월강우량과 저수율 사이의 회귀분석을 통하여 일정한 법칙을 만들 수 있는지 시도하였다. 다목적 댐인 소양강댐과 충주댐의 1984-2013년의 일별 저수율 자료로부터 저수율 관리관행을 파악할 수 있었는데, 다목적 댐인 관계로 호우시의 홍수피해 예방을 위하여 6월말에는 25-35% 정도의 저수율을 유지하도록 관리가 이루어지고 있었으며 호우가 발생된 이후에는 일정량을 수시로 방류하여 다음 호우를 준비하고 있는 것으로 나타났다. 또한 각 댐의 최저 저수율은 3월말 - 4월에 발생하는 것으로 나타났으며, 4월과 5월에 일정 정도의 강우량만 존재한다면 가뭄피해는 발생하지 않는 것으로 나타났다. 이와 같은 저수율 관리 관행을 적용하여 예측되는 강우량 패턴에 따른 저수율 변화를 예측하기 위하여 월강우량 자료와 4월 1일 기준의 저수율 자료 사이의 회귀분석을 실시하여 전년의 7월부터 당해 3월까지의 월강우량으로부터 4월 1일의 저수율을 예측할 수 있는 의미 있는 결과를 도출하였다. 이러한 결과는 기후변화 등에 따른 미래에 예측되는 월강우량 자료로부터 각 댐의 4월 1일 기준 저수율 자료를 예측할 수 있으며, 4월 및 5월의 월강우량과 함께 분석함으로써 가뭄위험을 평가할 수 있는 한 방법으로 적절한 활용이 가능할 것으로 판단된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.68-70
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• 2014

Korean e-goverment has shown its development phase upgrade following the world' e-government evolution. By United Nations, Korea was ranked number one in e-government yet it was not even in top ten for past years. Even now, a number of Korean government organizations such as Ministry of Security and Public Administration and Ministry of Science, ICT and Future Planning have presented and executed various directions and strategies (for example, e-gov 3.0). On the other hand, World Economic Forum put Korea out of top 10 in Networked Readiness Index and hence wireless mobile communication of Korea is a weak point making difficulties for smart office and Bring Your Own Device (BYOD) implementation. This paper details the analysis of leading countries' strategies and policies on m-Government and provides some suggestions for Korean m-government.

• Journal of Intelligence and Information Systems
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• v.22 no.1
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• pp.83-105
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• 2016

Measuring an individual's subjective wellbeing in an accurate, unobtrusive, and cost-effective manner is a core success factor of the wellbeing support system, which is a type of medical IT service. However, measurements with a self-report questionnaire and wearable sensors are cost-intensive and obtrusive when the wellbeing support system should be running in real-time, despite being very accurate. Recently, reasoning the state of subjective wellbeing with conventional sentiment analysis and unstructured data has been proposed as an alternative to resolve the drawbacks of the self-report questionnaire and wearable sensors. However, this approach does not consider contextual polarity, which results in lower measurement accuracy. Moreover, there is no sentimental word net or ontology for the subjective wellbeing area. Hence, this paper proposes a method to extract keywords and their contextual polarity representing the subjective wellbeing state from the unstructured text in online websites in order to improve the reasoning accuracy of the sentiment analysis. The proposed method is as follows. First, a set of general sentimental words is proposed. SentiWordNet was adopted; this is the most widely used dictionary and contains about 100,000 words such as nouns, verbs, adjectives, and adverbs with polarities from -1.0 (extremely negative) to 1.0 (extremely positive). Second, corpora on subjective wellbeing (SWB corpora) were obtained by crawling online text. A survey was conducted to prepare a learning dataset that includes an individual's opinion and the level of self-report wellness, such as stress and depression. The participants were asked to respond with their feelings about online news on two topics. Next, three data sources were extracted from the SWB corpora: demographic information, psychographic information, and the structural characteristics of the text (e.g., the number of words used in the text, simple statistics on the special characters used). These were considered to adjust the level of a specific SWB. Finally, a set of reasoning rules was generated for each wellbeing factor to estimate the SWB of an individual based on the text written by the individual. The experimental results suggested that using contextual polarity for each SWB factor (e.g., stress, depression) significantly improved the estimation accuracy compared to conventional sentiment analysis methods incorporating SentiWordNet. Even though literature is available on Korean sentiment analysis, such studies only used only a limited set of sentimental words. Due to the small number of words, many sentences are overlooked and ignored when estimating the level of sentiment. However, the proposed method can identify multiple sentiment-neutral words as sentiment words in the context of a specific SWB factor. The results also suggest that a specific type of senti-word dictionary containing contextual polarity needs to be constructed along with a dictionary based on common sense such as SenticNet. These efforts will enrich and enlarge the application area of sentic computing. The study is helpful to practitioners and managers of wellness services in that a couple of characteristics of unstructured text have been identified for improving SWB. Consistent with the literature, the results showed that the gender and age affect the SWB state when the individual is exposed to an identical queue from the online text. In addition, the length of the textual response and usage pattern of special characters were found to indicate the individual's SWB. These imply that better SWB measurement should involve collecting the textual structure and the individual's demographic conditions. In the future, the proposed method should be improved by automated identification of the contextual polarity in order to enlarge the vocabulary in a cost-effective manner.

• Membrane Journal
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• v.6 no.3
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• pp.157-165
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• 1996

Polysulfone(PS) membranes were prepared from homogeneous PS solutions by the phase inversion technique. When propionic acid(PA) was added into a casting solution of n-methylpyrrolidone(NMP) and PS, precipitation rate of the solution film was accelerated. This kind of acceleration was consistent, even though a precipitating nonsolvent was changed from water to isopropanol. These phenomena were caused by decrease of nonsolvent tolerance in the casting solution due to addition of PA. PS powder was prepared by precipitation of a 3wt% solution in dimethylformamide(DMF) using ethanol as nonsolvent. Gas adsorption analysis of the powder showed that the capillary condensation sites were found in the powder structure. Membranes prepared from PS solution(15wt%) in NMP had the following characteristics of gas adsorption and water permeation. In gas adsorption analysis, the membrane precipitated using isopropanol showed low uptake of nitrogen gas and the capillary condensation sites were not found. On the contrary, a significant amount of the capillary condensation sites was found in the membrane coagulated by water, which was related to increase of nitrogen uptake. tn the membrane prepared froin the solution including PA, an increase of the Henry's law sites and the Langmuir sites was not found clearly. However, the capillary condensation sites were significantly increased, and the water transport also increased.

• Journal of Nutrition and Health
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• v.54 no.3
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• pp.292-304
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• 2021

Purpose: This study investigated the association between the mothers' use of home meal replacement (HMR) in their children's meals and the diet quality of their young children. Methods: Three hundred and thirty-seven mothers with five-year-old kindergartners in Sejong city participated in the survey from June to July 2020. The questionnaire consisted of the status of HMR use in children's meals and questions for assessing the nutrition quotient for preschoolers (NQ-P). The subjects were classified into three groups according to the frequency of HMR use in children's meals: using HMR more than three times a week (high-frequency group; [HG], n = 65), one-two times a week (moderate-frequency group; [MG], n = 145), and less than once a week (low-frequency group; [LG], n = 130). Results: The mothers' mean age was 38.3 years. The average monthly cost of purchasing HMRs was highest at 200,000-300,000 won in HG, 50,000-100,000 won in MG, and less than 50,000 won in LG (p < 0.001). The consumption frequency of processed meats, fast foods, processed beverages, and sweet & fatty snacks was significantly higher in the HG group than the other groups. The mean NQ-P score was 60.5 in HG, 63.0 in MG, and 64.5 in LG, showing a significant difference (p < 0.01). In the sub-score according to the three areas, there were no significant differences in balance and environment among the three groups. In the moderation area, however, the score was 44.1 in HG, 51.3 in MG, and 57.5 in LG Group, showing a significant difference (p < 0.001). Conclusion: The increase in HMR use was related to the decreased diet quality in the overall and moderation areas of children's diet. These results support the importance of nutrition education for mothers, which aims to reduce their children's access and exposure to processed foods, such as HMR.

• Journal of agricultural medicine and community health
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• v.25 no.1
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• pp.65-83
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• 2000

To know the relationship of general characteristics with activities of daily living(ADL) and instrumental activities of daily living(IADL), we carried out the study on the elderies living in Chollabuk-Do area during 6 months, from June to December in 1999. Study subjects were 281, women and men were 195(69.6%) and 85(30.4%) respectively. Mean ages of women and men were 71.9 and 70.8 respectively. 81.1% elderies has disease and 18.9% were disease free. Disease prevalences of movement joint disease, others, circulatory disease, digestive disease, dental disease, respiratory disease were 50.1%, 25.0%, 10.5%, 9.4%, 8.5%, and 6.3% respectively. The percentages to the use of medical institution in recent were 40.0% for hospital, 16.8% for oriental hospital, 14.5% for public health center, 10.9% for drug store, 10.0% for others, and 7.8% for dental service. The percentages to the improvement of symptom after the use of medical institution were 62.3% for normal, 19.4% for improvement, and 18.2% for non-improvement. The percentages to the health situation were 37.1% for bad, 35.7% for good, and 27.1% for normal. Activities of daily living were 67.1% for 6 scores, 27.9% for 5 scores, 2.1% for 4 scores and ADL of women was lower than the men's. Instrumental activities of daily living were 50.4% for 5 scores, 19.3% for 3 scores, 12.1% for 4 scores and IADL of women was lower than the men's. Frequencies of disability in ADL were 28.9% for incontinence, 6.1% for bathing, 2.9% for meal, 2.5% for walking around house, 1.8% for toilet use, 1.4% for dressing and disability frequencies of women in 6 items of ADL were higher than the men's. The percentages of high, intermediate, low ADL in activities of daily living were 67.1%, 32.5%, 0.4% respectively and decrease of high ADL, increase of intermediate ADL were found with the increasing of age. Frequencies of disability in IADL were 42.9% for payment in and out, 31.8% for payment of written claim, 21.1% for shopping, 16.4% for preparation of meal, and 11.8% for use of bus. All items of women in IADL was higher than the men's but preparation of meal. The percentages of high, intermediate, low IADL in instrumental activities of daily living were 50.4%, 42.5%, 7.1% and decrease of high IADL, increase of intermediate IADL were found with the increasing of age. Mean of ADL with the general characteristics was 5.56 and 2 variables of level of education, health situation were statistically significant. Mean of IADL with the general characteristics was 3.76 and 8 variables of age, sex, level of education, occupation, presence of spouse, duty of living cost, health situation, category of ADL were statistically significant. With the result of stepwise regression, ADL was statistically related with religion, health situation and ADL was statistically related with level of education, living together with family, duty of living cost, health situation.