• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.97-97
• /
• 2013

Recently, Cu2ZnSn(S,Se)4 (CZTSS), which is one of the In- and Ga- free absorber materials, has been attracted considerable attention as a new candidate for use as an absorber material in thin film solar cells. The CZTSS-based absorber material has outstanding characteristics such as band gap energy of 1.0 eV to 1.5 eV, high absorption coefficient on the order of 104 cm-1, and high theoretical conversion efficiency of 32.2% in thin film solar cells. Despite these promising characteristics, research into CZTSS based thin film solar cells is still incomprehensive and related reports are quite few compared to those for CIGS thin film solar cells, which show high efficiency of over 20%. I will briefly overview the recent technological development of CZTSS thin film solar cells and then introduce our research results mainly related to sputter based process. CZTSS thin film solar cells are prepared by sulfurization of stacked both metallic and sulfide precursors. Sulfurization process was performed in both furnace annealing system and rapid thermal processing system using S powder as well as 5% diluted H2S gas source at various annealing temperatures ranging from $520^{\circ}C$ to $580^{\circ}C$. Structural, optical, microstructural, and electrical properties of absorber layers were characterized using XRD, SEM, TEM, UV-Vis spectroscopy, Hall-measurement, TRPL, etc. The effects of processing parameters, such as composition ratio, sulfurization pressure, and sulfurization temperature on the properties of CZTSS absorber layers will be discussed in detail. CZTSS thin film solar cell fabricated using metallic precursors shows maximum cell efficiency of 6.9% with Jsc of 25.2 mA/cm2, Voc of 469 mV, and fill factor of 59.1% and CZTS thin film solar cell using sulfide precursors shows that of 4.5% with Jsc of 19.8 mA/cm2, Voc of 492 mV, and fill factor of 46.2%. In addition, other research activities in our lab related to the formation of CZTS absorber layers using solution based processes such as electro-deposition, chemical solution deposition, nano-particle formation will be introduced briefly.

• 재활복지
• /
• v.20 no.3
• /
• pp.105-124
• /
• 2016

The This study aims to verify the causal relationship among physically disability persons participation in exercise, heart rate variance, and facial expression recognition. To achieve such research goal, this study targeted 139 physically disability persons and as for sampling, purposive sampling method was applied. After visiting a sporting stadium and club facilities that sporting events were held and explaining the purpose of the research in detail, only with those who agreed to participate in the research, their heart rate variance and facial emotion awareness were measured. With the results of measurement, mean value, standard deviation, correlation analysis, and structural equating model were analyzed, and the results are as follows. The quantity of exercise positively affected sympathetic activity and parasympathetic activity of autonomic nervous system. Exercise history of physically disability persons was found to have a positive influence on LF/HF, and it had a negative influence on parasympathetic activity. Sympathetic activity of physically disability persons turned out to have a positive effect on the recognition of the emotion, happiness, while the quantity of exercise had a negative influence on the recognition of the emotion, sadness. These findings were discussed and how those mechanisms that are relevant to the autonomic nervous system, facial expression recognition of physical disability persons.

• Korean Journal of Heritage: History & Science
• /
• v.45 no.1
• /
• pp.52-69
• /
• 2012

This paper attempts to analyze the inner and outer structure of royal tombs that were built during the Joseon Period. This analysis is based on the relevant historical records and they were restored through visual composition in order to compare the features of Joseon royal tombs with those of Goryeo royal tombs and common tombs of the Joseon Period. Royal tombs of the Joseon Dynasty are structurally solid and contain a variety of artistic ornaments that symbolize guardian deities both inside and outside to protect the owners of the tombs for a long time. According to historical records such as Sejong sillok oryeui (Five Rites of State from the Annals of King Sejong) and Gukjo oryeui (Five Rites of State), it is presumed that the inner structure of royal tombs dating back to the early Joseon Period consisted of a stone chamber and that the byeongpungseok and nanganseok were built outside of the tomb. However, ever since King Sejo left it in his will not to make a stone chamber in his tomb, the royal tombs began to follow a new pattern, a burial pit outside the coffin filled with lime powder. Gukjo sangnye bopyeon (Supplement Book of the State Funeral Rites), which was compiled during the reign of King Yeongjo, is a book that shows how the royal tombs were formed in the late Joseon Period. The book explains in detail how lime powder was used to fill the burial pit of royal tombs. The byeongpungseok used during the late Joseon Period were engraved with peony flowers, while those previously made were engraved with twelve spirit warriors. Peony designs were frequently used to decorate the items of royal families, and the use of peony designs in tombs reflects the idea of regarding the royal tombs as an everyday living space for the deceased.

• Journal of the Korean Society of Mineral and Energy Resources Engineers
• /
• v.55 no.6
• /
• pp.576-587
• /
• 2018

This study has focused on analysis factors affecting safety monitoring system at tailings sites, and the evaluation equipment to monitor the factors. Twenty sites at eighteen mines with unsafe conditions were selected to examine the equipment. There were three main factors influenced safety in the sites including surface erosion, piping, and slope instability. In detail, the surface erosion was divided into three sub-factors (planting, soil-topping layer, and tailings), piping into three sub-factors (liner, rain protection facility and leachate), and slop instability was also divided into three sub-factors (slop, concrete wall, and reinforcing wall). As results of in-field measurement, a CCTV was the most effective facility, and electrical resistivity survey, acoustic sensing, thermal liner sensor, structure inclinometer, rainfall meter, and flowmeter were also highly effective. According to applications of the facilities in the unstable tailings, structural defects were mainly found in the piping, which was the most important monitoring factor for safety management of tailings sites.

• International Area Studies Review
• /
• v.13 no.2
• /
• pp.190-222
• /
• 2009

This study is for analyzing the management performances of Korean tourism firms, which have been operating as preparing strategically against FTA, one of the most importantly external environment in international management since in the middle of 1990s. The main purpose can be mentioned to test empirically some relations between the management performances of Korean tourism ones and the levels of understanding and preparing against FTA. In detail speaking, the dependent variables of management performances are classified with sales, profits and management satisfaction, while the independent ones regarding with FTA are sorted based on the previous studies with the 2 following factors like understanding/preparing of managers and one of workers in a firm. This study is conducted in two stages. Firstly, the research model is designed by the reviewing relevant theories, previous studies. Secondly, the survey of Korean tourism enterprises engaging in management activities in Korea is implemented by collecting questionnaires. And for testing the hypothesis, the analyzing tools are being used for correlation, reliability, validity and multi regression on SPSS 12.0 for windows and finally the path analysis of structural equation modeling is activated with AMOS 7.0 for windows.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.16 no.1
• /
• pp.21-35
• /
• 2021

Based on social capital theory, this study investigated the influence of the start-up founder's social competence on the start-up's access to funding sources and performance through the mediating role of the type of social network. This study aimed to examine two types of social networks empirically (i.e., personal networks and business networks) as social capital in analyzing the effect of the founder's social competence and social capital on the method of accessing funding sources. A self-report questionnaire was administered to 252 South Korean start-up founders whose businesses are based in South Korea. Path analysis and mediation effect analysis were performed by structural equation modeling(SEM) using STATA 16.1. This study examined the full mediating effect of the founder's social competence on his/her personal and business networks, respectively, and how the effect leads to different methods to approach funding sources. This is the first study in South Korea to analyze empirically how social competence has contrasting effects on personal and business networks as well as how each type of network varies in its influence on the method founders use to attract investment. This study is also significant in that it proposed a new methodology by utilizing the position generator as the measure of personal and business networks to analyze social networks in detail. The analyses of 252 survey data collected over a period of six months will be a valuable resource that may provide researchers, founders, investors, and other stakeholders in the start-up ecosystem with meaningful implications.

• Korean Journal of Heritage: History & Science
• /
• v.54 no.1
• /
• pp.32-51
• /
• 2021

Architectural evidence of Gaya is insignificant than any other area. In this situation, house-shaped earthenware is particularly helpful in the study of Gaya architecture. However, house-shaped earthenware is not a building, it has just the shape of buildings. So, we have to find out architectural evidence from that. In this paper, I tried to estimate the architectural characteristics of Gaya through house-shaped earthenware in detail. I also consulted historical records, archeological results, and other scholars' papers. The results are as follows. First, house-shaped earthenware can be classified into three types according to its shape, and each type has distinct architectural structural characteristics. Second, house-shaped earthenware generally has a gambrel roof, and the characteristic of architectural design with the gable side of the gambrel roof as a front is the biggest feature of Gaya architecture. Third, various types of buildings existed according to their functions in Gaya architecture, and house-shaped earthenware was showed buildings of ancient storage, pens, and residences, which are symbols of the richness among various types of buildings.

• Structural Engineering and Mechanics
• /
• v.83 no.3
• /
• pp.305-326
• /
• 2022

To realize the recycling utilization of waste concrete and alleviate the shortage of resources, 11 specimens of steel reinforced recycled concrete (SRRC) filled circular steel tube columns were designed and manufactured in this study, and the cyclic loading tests on the specimens of columns were also carried out respectively. The hysteretic curves, skeleton curves and performance indicators of columns were obtained and analysed in detail. Besides, the finite element model of columns was established through OpenSees software, which considered the adverse effect of recycled coarse aggregate (RA) replacement rates and the constraint effect of circular steel tube on internal RAC. The numerical calculation curves of columns are in good agreement with the experimental curves, which shows that the numerical model is relatively reasonable. On this basis, a series of nonlinear parameters analysis on the hysteretic behaviors of columns were also investigated. The results are as follows: When the replacement rates of RA increases from 0 to 100%, the peak loads of columns decreases by 7.78% and the ductility decreases slightly. With the increase of axial compression ratio, the bearing capacity of columns increases first and then decreases, but the ductility of columns decreases rapidly. Increasing the wall thickness of circular steel tube is very profitable to improve the bearing capacity and ductility of columns. When the section steel ratio increases from 5.54% to 9.99%, although the bearing capacity of columns is improved, it has no obvious contribution to improve the ductility of columns. With the decrease of shear span ratio, the bearing capacity of columns increases obviously, but the ductility decreases, and the failure mode of columns develops into brittle shear failure. Therefore, in the engineering design of columns, the situation of small shear span ratio (i.e., short columns) should be avoided as far as possible. Based on this, the calculation model on the skeleton curves of columns was established by the theoretical analysis and fitting method, so as to determine the main characteristic points in the model. The effectiveness of skeleton curve model is verified by comparing with the test skeleton curves.

• The Journal of Korean-Japanese National Studies
• /
• no.34
• /
• pp.77-123
• /
• 2018

The liberated korea has the estimated population 16 million in 1945, and added 2.5 million just after an year. The korean repatriates returned by way of 2 main routes. The returnees, Wol-Nam-Min(former residents in north korea), and repatriates from Manchuria came into south korea over the 38th division line. The other repatriates from japanese islands and pacific areas came into Busan port and the vicinity. The repatriates who returned from the China and the Japanese islands made up about 80% of the total added population. However, the influx of overseas repatriates who explosively increased between 1945 and 1946, declined abruptly in April of 1946, and at last illegal re-emigration group to Manchuria and Japan Appeared, who had repatriated from those areas. This study deals with the "re-migration phenomenon of 1946" in korea, mainly focuses on 1) the motivation for those who decided to remigrate, their prospects of resettlement in Manchuria and post war japan after re-migration, 2) the structural problems of the Korean society in 1946-1947, and 3) the social recognition for the people who letf for Manchuria and Japan. This study proved the cause and background of re-migration phenomenon. The Manchuria case, the local authorities wanted farmers and peasants who could cultivate the abandoned land which had been originally pioneered and reclaimed by korean poor peasants, who repatriated to korean peninsula. On the other hand, the korean repatriates had a hard time in tenanting farmland, and so much difficulty in getting farming tools including fertilizer. That's why they left korea for Manchuria again. The Japanese case, the korean repatriates had a tough life owing to the restriction of properties left in japan, while the inflation and food shortage in korea got worse and worst. Accordingly, many koreans tried illegal entrance into post war japan. This study is a part of clarifying the universality and specificity of post war repatriation and migration issues developed in the south Korea. Through this study, we can find how difficult it is for newly liberated areas to accommodate repatriates and make them ordinary nationals in harmonic way with successful social integration. and we can observe the social aspect and administrative ability of newly liberated south korea in detail, Because the present korea has faced with so many problems connected with immigration workers and re-setting with korean communities abroad, we should introspect these historical experience of our own.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.1A
• /
• pp.61-73
• /
• 2009

In this paper, hybrid health monitoring techniques using acceleration-impedance features are newly proposed to detect two damage-type in steel plate-girder bridges, which are girder's stiffness-loss and support perturbation. The hybrid techniques mainly consists of three sequential phases: 1) to alarm the occurrence of damage in global manner, 2) to classify the alarmed damage into subsystems of the structure, and 3) to estimate the classified damage in detail using methods suitable for the subsystems. In the first phase, the global occurrence of damage is alarmed by monitoring changes in acceleration features. In the second phase, the alarmed damage is classified into subsystems by recognizing patterns of impedance features. In the final phase, the location and the extent of damage are estimated by using modal strain energy-based damage index method and root mean square deviation (RMSD) method. The feasibility of the proposed hybrid technique is evaluated on a laboratory-scaled steel plate-girder bridge model for which hybrid acceleration-impedance signatures were measured for several damage scenarios. Also, the effect of temperature on the accuracy of the impedance-based damage monitoring results are experimentally examined from combined scenarios of support damage cases and temperature changes.