• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.661-661
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• 2013

열전재료는 열-전기가 상호 가역적으로 변하는 재료로서, 에너지 변환소재 분야에서 널리 각광받고 있다. 열전재료의 성능은 무차원 열전성능지수(dimensionless figure of merit, $ZT={\alpha}^2{\sigma}T/{\kappa}$)로 평가된다. 여기서 ${\alpha}$는 제벡계수(Seebeck coefficient), ${\sigma}$는 전기전도도(electrical conductivity), ${\kappa}$는 열전도도(thermal conductivity), T는 Kelvin 온도를 나타낸다. 500 K에서 800 K까지의 중온 영역에서 우수한 열전특성을 보이는 $Mg_2X$ (X=Si, Ge, Sn)와 이들의 고용체는 성분원소가 독성이 없고, 매장량이 많아 친환경 열전재료로 각광받고 있다. $Mg_2X$ 고용체 중 $Mg_2Si-Mg_2Sn$ 고용체는 Si와 Sn의 큰 원자량 차이로 인해 낮은 열전도도와 높은 성능지수(ZT)를 얻을 것이라 예상되며 열전발전 소자로서의 응용이 기대된다. Sb가 도핑된 $Mg_{2+x}Si_{0.7}Sn_{0.3}Sb_y$ (x=0, 0.1, 0.2, y=0, 0.01) 고용체를 고상합성과 기계적 합금화로 합성한 후, 진공 열간압축 성형을 통해 성공적으로 제조하였다. X선 회절분석으로 상합성과 고용체 형성 여부를 확인하였고, Mg의 과잉첨가와 Sb 도핑에 따른 열전특성의 변화를 조사하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.636-640
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• 2011

Film cooling technique has been applied to effectively reduce thermal load on liquid rocket combustion chambers by direct injection of a portion of propellant, which flows through the regeneratively cooling channels, into the chamber wall. This study developed a comprehensive model to quantitatively predict the effects of kerosene film cooling on propulsive performance and wall cooling at supercritical pressure conditions, and assessed the predictive capability against hot-firing tests of an actual combustor. The present model is expected to be utilized as a design and analysis tool to meet the conflicting requirements in terms of performance, cooling, pressure loss and weight.

• Journal of the military operations research society of Korea
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• v.37 no.1
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• pp.99-118
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• 2011

According to the National Contract Law, when determining Estimation cost Contract officers should consider contract quantity, contract period, supply and demand condition, difficulty of contract enforcement, terms and condition, and other various conditions based market price, costing based pricing, and appraisal. And they should not overestimate or underestimate the estimation cost. But the estimation cost system is used as preparedness for audit against the contract law. In this study, we identified the factors affecting estimation cost and analyzed their influence on estimation cost.

• Journal of Korea Port Economic Association
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• v.35 no.3
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• pp.41-60
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• 2019

This study aims to identify factors that pharmaceutical logistics companies must consider when selecting a logistics center; it also aims to analyze the importance-satisfaction-of these factors by using IPA. The main results are as follows. First, overall, the aforementioned factors are divided into logistics factor, economic factor, environmental factor, and policy factor, and most of the specific attributes of each main factor are less satisfied than the importance. Second, the users of pharmaceutical logistics are divided into producers, distributors, clinics, and pharmacies. The analysis of each user shows a need to improve logistics factors as well as an overinvestment in environmental factors. The results can provide drug distribution companies directions for selecting logistics centers as well as strategic implications.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.25 no.2
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• pp.77-127
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• 1999

활성 산소종은 노화, 특히 피부노화의 원인 물질로 작용하고 있다. 피부는 자외선에 노출되어 있어 활성 산소종을 만드는 광화학적 반응들이 계속해서 일어나고 있다. 이들 활성 산소종들은 피부 세포 및 조직 손상을 주도한다. 이들은 항산화 효소와 비효소적 항산화제들로 구성된 항산화 방어망을 파괴함으로써 산화제/항산화제 균형을 산화 상태 쪽으로 기울게 한다. 결과적으로 계속된 산화적 스트레스는 지질 과산화, 단백질 산화, 간질 성분을 파괴시키는 단백질분해효소의 활성화, 탄력 섬유인 콜라겐과 엘라스틴의 사슬절단 및 비정상적인 교차결합, 히아루론산 사슬의 절단, 멜라닌 생성반웅 촉진, DNA 산화와 같은 생체 구성 성분들의 손상을 야기시킨다. 결국에는 탄력감수 주름살 및 기미.주근깨 둥으로 특징 지워지는 피부노화가 가속화된다. 따라서 피부노화 방지를 위해서는, 과잉의 활성 산소종 생성을 억제하고 또한 생성된 활성산소를 효율적으로 제거할 수 있는 시스템이 화장품의 처방에 반드시 포함될 필요가 있다. 즉, 산화제/항산화제 밸런스가 유지되는 피부의 항산화 방어 시스템 구축이 필요하다. 피부노화 방지에 있어서 천연물의 역할로 (1) 자외선 흡수제로서의 역할, (2) 항산화제로서의 역할, (3) 주름 개선제로서의 역할, (4) 미백제로서의 역할, (5) 항균\ulcorner항염작용 및면역 조절제로서의 역할에 대하여 살펴 보았다. 21세기는 본격적으로 기능성 화장품 시대가 개막될 것으로 예측하고 있다. 이에 맞춰 천연물들은 피부노화를 방지하는데 주도적인 역할을 할 것으로 기대된다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.409-410
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• 2019

본 논문에서는 국내 갑상선암의 연구 동향을 파악하기 위해 텍스트 중심의 접근법을 제안한다. 국내 갑상선암은 2000년대에 들어서며 발생이 급증하여 과잉진단의 논란을 불러일으켰으나, 다양한 분야의 자정 노력으로 수술 환자수가 크게 줄었다. 본 연구에서는 텍스트 마이닝 기술을 사용하여 디비피아에 등록되어 있는 갑상선암 관련 논문의 키워드와 초록을 수집하여 분석하였다. 1980년대는 대부분의 사례보고가 있었고 1990년대에 들어서면서 검진을 통한 조기 진단의 내용이 자주 나타났다. 2000년대에는 여러 장비들을 활용한 검사방법과 미세한 암의 발견에 대한 논의가 증가하였음을 확인 할 수 있었다. 2010년대에 들어서는 환자의 삶의 질에 대한 연구가 많이 이루어졌다. 지난 수십 년 동안 갑상선 암 연구 주제에 대해 뚜렷한 변화가 나타났으며, 향후 연구의 기초자료로 활용될 수 있으리라 기대된다.

• Journal of Preventive Medicine and Public Health
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• v.26 no.4 s.44
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• pp.628-649
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• 1993

This study was conducted to investigate the factors related to the poor school performance of the elementary school children. Two schools in Taegu, one in the affluent area and the other in the poor area, were selected and a total of 175 children whose school performance was within low 10 percentile (poor performers) and 97 children whose school performance were within high 5 percentile (good performers) in each class of 2nd, 4th and 6th grades were tested for the physical health, behavioral problem and family background. Each child had gone through a battery of tests including visual and hearing acuity, anthropometry (body weight, height, head circumference), intelligence (Kodae Stanford-Binet test), test anxiety (TAI-K), neurologic examination by a developmental pediatrician and heavy metal content (Pb, Cd, Zn) in hair by atomic absorption spectrophotometry. A questionnaire was administered to the mothers for prenatal and prenatal courses of the child, family environment, child's developmental history, and child's behavioral and learning problems. Another questionnaire was administered to the teachers of the children for the child's family background, arithmatic & language abilities and behavioral problem. The poor school performance had a significant correlation with male gender, high birth order, broken home, low educational and occupational levels of parents, visual problem, high test anxiety score, attention deficit hyperactivity disorder (ADHD), poor physical growth (weight, height, head circumference) and low I.Q. score. The factors that had a significant correlation with the poor school performance in multiple logistic regression analysis were child's birth order (odds ratio=2.06), male gender(odds ratio=5.91), broken home(odds ratio=9.29), test anxiety score(odds ratio=1.07), ADHD (odds ratio=9.67), I.Q. score (odds ratio=0.85) and height less than Korean standard mean-1S.D.(odds ratio=11.12). The heavy metal contents in hair did not show any significant correlation with poor school performance. However the lead and cadmium contents were high in males than in females. The lead content was negatively correlated with child's grade(P<0.05) and zinc was positively correlated with grade (P<0.05). among the factors that showed a significant correlation with the poor school performance, high birth order, short stature and ADHD may be modified by a good family planning, good feeding practice for infant and child, and early detection and treatment of ADHD. Also, teacher and parents should restrain themselves from inducing excessive test anxiety by forcing the child to study and over-expecting beyond the child's intellectual capability.

• The Korean Journal of Soil Zoology
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• v.5 no.2
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• pp.125-131
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• 2000

Disposing technique for dairy cattle manure using earthworms and the possibility of utilizing earthworms in poultry feed were investigated. In addition, chemical properties of manure and cast of earthworms were investigated. Temperature in the vinyl-house for earthworm nursery was able to be maintained above 0$\^{C}$ in winter and 25-28$\^{C}$ in summer. In closed-covering method, the number of escaped earthworms was the highest among three covering methods. The time was longer after manure excretion, the numbers of escaped earthworm were higher. There were some incidences of mortality of earthworm in closed-covering site. The amount of manure ingested by earthworm was increased in order of non-covering, closed-covering and gap-covering method. Fresh manure was more ingested than old one by earthworm. Earthworms reduced manure about 50% on the dry weight base and reduced total amounts of N, P$_2$O$\_$5/ and K$_2$O of manure by 41, 50 and 60%, respectively. Earthworm could be utilized by adult poultry (>60 g) for feeding. However, adverse effect of live earthworm was observed with young poultry (<450 g).

• Journal of the Korean Data and Information Science Society
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• v.28 no.3
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• pp.493-504
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• 2017

We often observe count data that exhibit over-dispersion, originating from too many zeros, and under-dispersion, originating from too few zeros. To handle this types of problems, the zero-altered distribution model is designed by Ghosh and Kim in 2007. Their model can control both over-dispersion and under-dispersion with a single parameter, which had been impossible ever. The dispersion type depends on the sign of the parameter ${\delta}$ in zero-altered distribution. In this study, we demonstrate the role of the dispersion type parameter ${\delta}$ through the data of the number of births in Korea. Employing both the chi-square statistic and the Kolmogorov statistic for goodness-of-fit, we also explained any difference between the theoretical distribution and the observed one that exhibits either over-dispersion or under-dispersion. Finally this study shows whether the test statistics for goodness-of-fit show any similarity with the role of the dispersion type parameter ${\delta}$ or not.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.389-402
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• 2018

This study investigated the influence of parenting attitudes and parenting efficacy on parents' educational needs to establish basic data for educational programs and intervention strategies to promote parenting attitudes and parenting efficacy among married immigrant women. This was a study of descriptive correlation among 154 married immigrant women with adolescent children. The results showed that family support and spousal support influenced parenting behavior and stress associated with childcare. Specifically, spousal support and family support were negatively correlated (r = 0.046, F = 3.629 p < 0.05) with parenting attitude (r = 0.046, F = 3.629 p < 0.05). Only spousal support was negatively correlated (r =0.227, F = 7.11 .<.01) with stress from children. Moreover, higher support from the spouse and family was associated with lower parenting stress and higher spousal support was associated with lower stress associated with the relationship with the child. The results of this study will facilitate development of a structured education program for married immigrant women to enhance parenting attitudes, as well as to reduce parenting stress.