• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.53-53
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• 2011

This paper describes results for surface and bulk characterization of the most promising thin film solar cell material for high performance devices, (Ag,Cu) (In,Ga) Se2 (ACIGS). This material in particular exhibits a range of exotic behaviors. The surface and general materials science of the material also has direct implications for the operation of solar cells based upon it. Some of the techniques and results described will include scanning probe (AFM, STM, KPFM) measurements of epitaxial films of different surface orientations, photoelectron spectroscopy and inverse photoemission, Auger electron spectroscopy, and more. Bulk measurements are included as support for the surface measurements such as cathodoluminescence imaging around grain boundaries and showing surface recombination effects, and transmission electron microscopy to verify the surface growth behaviors to be equilibrium rather than kinetic phenomena. The results show that the polar close packed surface of CIGS is the lowest energy surface by far. This surface is expected to be reconstructed to eliminate the surface charge. However, the AgInSe2 compound has yielded excellent atomic-resolution images of the surface with no evidence of surface reconstruction. Similar imaging of CuInSe2 has proven more difficult and no atomic resolution images have been obtained, although current imaging tunneling spectroscopy images show electronic structure variations on the atomic scale. A discussion of the reasons why this may be the case is given. The surface composition and grain boundary compositions match the bulk chemistry exactly in as-grow films. However, the deposition of the heterojunction forming the device alters this chemistry, leading to a strongly n-type surface. This also directly explains unpinning of the Fermi level and the operation of the resulting devices when heterojunctions are formed with the CIGS. These results are linked to device performance through simulation of the characteristic operating behaviors of the cells using models developed in my laboratory.

• Advanced Composite Materials
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• 제18권3호
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• pp.265-285
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• 2009

Off-axis compressive deformation behavior of a unidirectional CFRP laminate at high temperature and its strain-rate dependence in a quasi-static range are examined for various fiber orientations. By comparing the off-axis compressive and tensile behaviors at an equal strain rate, the effect of different loading modes on the flow stress level, rate-dependence and nonlinearity of the off-axis inelastic deformation is elucidated. The experimental results indicate that the compressive flow stress levels for relatively larger off-axis angles of $30^{\circ}$, $45^{\circ}$ and $90^{\circ}$ are about 50 percent larger than in tension for the same fiber orientations, respectively. The nonlinear deformations under off-axis tensile and compressive loading conditions exhibit significant strain-rate dependence. Similar features are observed in the fiber-orientation dependence of the off-axis flow stress levels under tension and compression and in the off-axis flow stress differential in tension and compression, regardless of the strain rate. A phenomenological theory of viscoplasticity is then developed which can describe the tension-compression asymmetry as well as the rate dependence, nonlinearity and fiber orientation dependence of the off-axis tensile and compressive behaviors of unidirectional composites in a unified manner. It is demonstrated by comparing with experimental results that the proposed viscoplastic constitutive model can be applied with reasonable accuracy to predict the different, nonlinear and rate-dependent behaviors of the unidirectional composite under off-axis tensile and compressive loading conditions.

• 한국실내디자인학회논문집
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• 제15권2호
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• pp.150-157
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• 2006

Founded on a close relationship between exhibition scenarios and media, this study was conducted 1) to establish exhibition arrangement types by using three analytical indicators, such as arrangement types of exhibition, groupings of similar exhibition media, and exhibition density; and 2) to demonstrate the importance of considering the characteristics of exhibition arrangement types by using viewing behavior codes as a major analytical indicator. The following three types were investigated in this research: First, the Independent type (Type C) was found to be strongly influenced by architectural and spatial forms, especially by low exhibition density and high visual information. Also, compared with the Wall Dominant type, low number of viewing behavior codes and distribution was found even though there were high correlations among viewing behavior codes. This is assumed to be due to low exhibition density. Second, the Wall Dominant type (Type A) was found to be not influenced by architectural and spatial forms. This is because space is planned and restructured centering on the wall type showcases. At the planning stage of exhibition, it is easy to divide or combine space according to the contents and structure of exhibition scenarios. Compared with the Independent type, low correlations were found among viewing behavior codes. This is due to low participation or manipulation exhibitions. However, this implies that more active viewing behaviors can be induced if appropriate exhibition techniques and arrangement methods are used for each exhibition content. Third, the Independent Dominant type (Type B) was found to confuse visitors in selecting routes by displaying too many exhibits at a limited space in a disorderly fashion. It failed to attract visitors to the main exhibition area, where a big space is formed in the center. Visitors were found to view exhibits that are arranged near the major traffic line.

• 대한영양사협회학술지
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• 제18권4호
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• pp.283-296
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• 2012

As a disease that reduces quality of life, functional dyspepsia (FD) is associated with foods that may worsen its symptoms or cause it. The purpose of this study was to examine the nutritional status and dietary behaviors of FD patients. We investigated food intake, food intake frequency, and dietary habits of 45 FD subjects according to the Rome III Diagnosis Criteria. Average age and body mass index (BMI) were 47.7 years and $22.6kg/m^2$ (males: $23.4kg/m^2$, females: $22.1kg/m^2$), respectively. Average energy intake was 77% of Korean Dietary Reference Intake (KDRI), and it was less than that of the Korea National Health and Nutrition Examination Surveys (KNHANES). Other nutrient intake levels were similar to the KNHANES. Energy intake proportion of carbohydrates : protein : fat was 56 : 18 : 26, and the ratio of fat intake was higher than that of the KNHANES. Beans, laver, tomato, and yogurt were consumed very frequently. In the results of meal regularity, dietary behaviors and composition of diet were relatively good. It is likely that the patient controlled their diet by eating cautiously and by reducing alcohol drinking and smoking. Our results indicate that FD patients' nutritional status by consumption of nutrients was at a level of normal healthy people and that dietary habits were better than normal adults. However, their fat intake levels were somewhat higher than normal people. Therefore, further research is required to identify the relationship between dietary intakes and FD.

• 한국ITS학회 논문지
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• 제16권6호
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• pp.16-28
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• 2017

본 연구에서는 운수종사자시스템과 운행기록분석시스템을 활용하여 시내버스 고령운전자 운전적성정밀검사의 신규검사결과, 사고 및 벌점현황, 운행기록자료를 분석하였다. 분석결과 시내버스 고령운전자를 사고수가 많은 관심대상 운수회사와 관리가 잘 되고 있는 교통안전 우수회사와 비교했을 경우 운전적성정밀검사의 결과는 비슷하였으나 최근 5년 동안 운행하면서 발생한 총 벌점은 상당한 차이를 보였고 사고의 경우 평균 중상자수와 경상자의 수도 적은 것으로 확인됐다. 또한 운행 100km당 위험운전행동 횟수를 비교해보면 우수회사의 고령운전자는 다른 고령운전자와 비고령운전자와 비교해서도 위험운전행동 횟수가 상당히 적은데 잘못된 운전습관의 교정결과에 따른 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.1021-1030
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• 2007

The effects of the creamide III (CER3) and cholesterol (CHOL) on the structure of a non-hydrous distearoyl phosphatidylcholine (DSPC)-based lamellar liquid crystal (LC) hydrated by only propylene glycol (PG) without water were investigated by differential scanning calorimetry (DSC), X-ray diffractions (XRDs), and polarized microscope (PM). As soon as CER3 was incorporated into the lamellar phase, the characteristic LPP was appeared as well as the characteristic SPP, and the formation of separated CER3 crystalline phase was observed depending upon the increase of CER3 content by XRDs. Also, by DSC, it was shown that the increase of CER3 made the monotectic thermal transition be changed to the eutectic thermal transition which indicates the formation of separated CER3 crystalline phases and the main transition temperatures (Tc1) to be gradually decreased and the enthalpy change (ΔH) to be linearly increased. Incorporating CHOL, the formation of LPP and SPP showed almost similar behaviors to CER3, but incorporating small amounts of CHOL showed the characteristic peaks of CHOL which meant the existence of crystalline CHOL phase due to the immiscibility of CHOL with DSPC swollen by PG differently from CER3, and increasing CHOL made the intensity of the 1st order diffraction for LPP weakened as well as the intensities of the characteristic diffractions for DSPC. Also, in the results of DSC, it showed more complex thermal behaviors having several Tc than CER3 due to its bulky chemical structure. In the present study, the inducement of CER3 and CHOL as other lipids present in human stratum corneum (SC) into a non-hydrous lamellar phase is discussed in terms of the influence on their structural and thermal transition.

• 한국치위생학회지
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• 제11권4호
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• pp.511-522
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• 2011

Objectives : The purpose of this study was to provide some information on the development of oral health care programs geared toward diabetics and ways of promoting their oral health. Methods : The subjects in this study were 586 diabetics who were selected from the 2009 third-year raw data of the 4th(2007~2009) National Health & Nutrition Survey. The data were analyzed with the statistical package SPSS 12.0 to grasp the influence of their sociodemographic characteristics and oral health behaviors on the presence or absence of periodontal diseases and missing tooth. Results : 1. Periodontal diseases were twofold more prevalent among the men than the women(p<0.01). By age, those who were in their 60s had 1.11-fold more periodontal diseases than those who were in their 70s and up(p<0.05). 2. The men and women were similar to each other in the number of missing tooth. By age, the number of missing tooth got smaller in proportion to decrease in age. By income, the number of missing tooth was 1.48-fold larger among the patients who earned an income of one million won or less than those who earned an income of two million won or more(p<0.01). Conclusions : The above-mentioned findings suggest that prospective cohort studies should be implemented to present prediction models of periodontal diseases and diabetes instead of merely sticking to cross-sectional studies. And oral health programs should be developed based on the findings of cohort studies to encourage diabetics to care about their oral health, and in which way they should be helped to promote their oral health should carefully be considered.

• International Journal of Quality Innovation
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• 제3권2호
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• pp.183-198
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• 2002

The purpose of this research is mainly to make an analysis and comparison of the purchasing behaviors of consumers in Mainland China and Taiwan. We precede this research with a questionnaire survey. In Mainland China, we targeted consumers of 10 department stores of the Parkson Plaza Co., Ltd. that are located in 10 different cities. In Taiwan, we selected 3 department stores of the Far Eastern Department Stores in 3 cities. The results of this analysis indicate the importance of quality attributes to the consumers for both Mainland China and Taiwan, albeit with some differentiations. The consumers in China are more focused on the merchandise for example as well as imitation, quality and price. Contrarily, the consumers in Taiwan are more attentive to service quality and parking Issues. On the level of evaluation of satisfaction, the differences are not so obvious for both sides. For example, the quality attributes of “No imitation products” and “Friendly servers” are ranked as the most satisfactory items for both sides. Generally speaking, the service quality of Taiwan's department stores is very outstanding. There are also some differences in the areas of lesser satisfaction between consumers of China and Taiwan. The consumers in China identified the quality attribute “the designs of merchandising, display and the usage of each floor” as the most dissatisfactory item, while the performance on this quality attribute is well accepted by the consumers of Taiwan's department stores. Another contradiction is that Taiwan's consumers are more concerned about “Parking”; this quality attribute obtained much less attention from the consumers in Mainland China. From the analysis of determinants that will have impacts on the willingness of customers to buy again, we found that the viewpoints of consumers from both sides are quite similar. The two main factors are “quality of merchandise” and “service quality”. However, the consumers in Mainland China care more about “the price of merchandise”; this is less important to the consumers in Taiwan. We may conclude from the importance and satisfaction level of the quality attributes and determinants for return customers that differences are caused mainly by the different management of the department stores and the different living circumstances of people across the straights.

• 대한기계학회논문집A
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• 제38권2호
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• pp.177-184
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• 2014

본 논문에서는 보수용접부 폭 변화에 따른 이종금속 맞대기 용접부(Dissimilar metal butt weld) 용접잔류응력의 분포 및 동종금속용접/기계적 하중에 의한 재분배 거동을 평가하였다. 이를 위해 5가지 다른 보수용접부 폭을 고려한 상세 2차원 유한요소 열해석 및 응력해석을 수행하였다. 유한요소해석 결과를 바탕으로 보수용접에 의한 용접잔류응력 분포를 평가하였으며, 동종금속용접 및 기계적 하중에 의한 응력 재분배 특성을 평가하였다. 보수용접에 의해 배관 내면에서는 큰 인장 용접잔류응력이 축방향과 원주방향에 대해 발생하는 것으로 나타났으며 보수용접부 폭이 특정값 이상이 되면 용접잔류응력 분포가 변하는 것으로 나타났다. 그러나 동종금속용접과 기계적 하중을 고려하면 인장잔류응력값이 크게 감소하였으며 그 경향은 보수용접부 폭에 무관한 것으로 나타났다.

• 설비공학논문집
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• 제20권5호
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• pp.304-313
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• 2008

This paper investigates the indoor-air-quality (IAQ) characteristics of the interior space equipped with system air-conditioner. The behaviors of individual variables such as temperature, humidity and concentration of carbon dioxide ($CO_2$) that influence on IAQ of the interior space were characterized under various cooling conditions by numerical and experimental studies. The numerical analysis predicting the temperature behavior of the interior space was conducted, and its results showed a good agreement with the experimental ones. The $CO_2$ concentration and humidity were measured and their time dependent behaviors were monitored and analyzed. From the results, it was found that there existed the differences of the time-dependent behaviors of IAQ variables according to the locations. In addition, it is demonstrated that the large discharge angle of $45^{\circ}$ made the temperature profile more irregular and the high discharge flow of 5.34 m/s produced similar temperature profiles at three different sensing locations. Finally, the humidity of interior space was less sensitive to the changes of the air cooling conditions than the case of temperature and the $CO_2$ concentration increase mainly depended on the number of individuals inside the space.