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

• Quality Improvement in Health Care
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• v.7 no.1
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• pp.6-17
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• 2000

Background : This study was attempted to provide a basic information necessary for the development of measures evaluating perceived discomfort of the patients under local anesthesia and the developments of nursing intervention and nursing standard. Method : The study subjects were a convenience sample of 100 surgical patients under local anesthesia. The researcher visited the patients directly and explained the purpose of the study to them. Then they were asked to fill out questionnaires which were developed and structured by the researcher, under their prior permission. Out patient's data were collected at recovery room after operation. Results : Factor analysis on measures evaluating the patients under local anesthesia showed that the measures consisted of eight factors including "explanation", "humane treatment", "motion limitation", "pain", "no togetherness", "waiting", "the environment of operating room", and "unkindness". When analyzing each of the factors regarding their degree of contribution to perceived discomfort, it was found that "waiting" was highest in terms of the degree. According to general chara-cteristics of the sampled patients, the factor of "explanation" contributed to perceived discomfort more in male patients than female ones. Regarding parts of medical examination, the patients of otorhinolaryngology felt perceived discomfort most because of the factor of "pain". Conclusion : To relieve perceived discomfort the patients under local anesthesia require providing individually systematized nursing services which can reduce perceived discomfort according to each of the factors. In doing so, an unlimited attention and much effort should be given to realize CQI reaching the dimension of increase in comfort as well as decrease perceived discomfort.

• Journal of Korean Academy of Nursing
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• v.44 no.6
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• pp.735-742
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• 2014

Purpose: This study was performed to assess the reliability and validity of the Korean version of European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Chemotherapy-induced peripheral neuropathy 20 items (EORTC QLQ-CIPN20) in patients receiving neurotoxic chemotherapy. Methods: A convenience sample of 249 Korean cancer patients, previously or currently, being treated with peripheral neurotoxic chemotherapeutic agents were asked to fill in the questionnaire. Collected data were analyzed using SPSS 21.0 and AMOS 21.0. Construct validity, known-group validity, concurrent validity, and internal consistency reliability of the Korean version of the QLQ-CIPN20 were evaluated. Results: Factor analysis confirmed 3 dimensions of CIPN: sensory, motor, and autonomic. The factor loadings of the 20 items on the 3 subscales ranged from .38 to .85. The 3 subscale-model was validated by confirmatory factor analysis (GFI=.90, AGFI=.86, RMSR=.05, NFI=.87, and CFI=.94), and concurrent validity was demonstrated with the EORTC QLQ-C30. Furthermore, the QLQ-CIPN20 established known-group validity. The Cronbach's alpha coefficients for internal consistency of the subscales ranged from .73 to .89. Conclusion: The Korean version of the EORTC QLQ-CIPN20 showed satisfactory construct, concurrent, and known-group validity, as well as internal reliability.

• Journal of Korean Society for Quality Management
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• v.27 no.2
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• pp.1-19
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• 1999

It is truism to say that today's customers demand high quality products and services; nevertheless, nowhere is this more prevalent than in the medical industry. Korea's globalization has increased it's citizen's awareness of greater life expectancies and medical improvements in other regions of the globe. Therefore, it is universally essential that in order to be successful in the medical industry, vendors must meet the ever increasing demands of better educated customers. The purpose of this study was twofold: 1) The first objective was discover what health care services are in demand and the quality factors related to these services. 2) The second objective was to determine a strategy for improving health care service through quality function deployment(QFD). One hundred and ninety-five respondents were randomly selected and asked to fill out a questionnaire after having undergone treatment at a medical clinic, located in Daejon, South Korea. The questionnaire was designed to obtain information about both he clients' satisfaction with, and their sense of the value of the medical treatment they received. Penalty-reward analysis and QFD were used to interpret the survey results and to deploy the collective voices of the customers. The results of the penalty-reward analysis illustrated that the 'communication' service quality factor was classified into an excitement factor that incurs no penalty if not achieved but adds value if the requirement is exceeded. As a result of the QFD analysis on the 'communication' service quality factor, eleven strategic alternatives were prioritized, and isolated a vital service quality characteristic. This characteristic can be implemented to bring value-added changes for the improvement of health care services.

• Journal of Korean Academy of Nursing
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• v.27 no.4
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• pp.831-842
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• 1997

The purpose of the study was to test the reliability and validity of the Korean version of Task Self-Efficacy Scale for activities of dally living (ADL). The Task Self-Efficacy Scale was developed by Roberts(1996) for low-intensity exercise study with older people to predict their performance of ADL. The scale was translated and back translated by bilingual persons, and then was modified to resolve variations in the translations. The Korean version of Self-Efficacy Scale for ADL was then administered to 193 elderly people including 95 hospitalized patients and 98 outpatients or healthy people. Face to face interview was used to fill out the structured questionnaire, and each interview took approximately 30 minutes. The subjects for the study were 80 women and 112 men with an age range of 65 to 95 years(M=71 years) of whom 82.6% classified themselves as moderate or quite active Most subjects(80.2%) had an education level of elementary school or less. The Self-Efficacy Scale for ADL is measured on a 0 to 10 VAS, assessing three areas of ADL : self care activities, household tasks, and motor tasks. The higher the score is, the higher person's confidence in performing ADL. Psychometric testing revealed that the scale was found to be internally consistent, showing a Cronbach's alpha of .97 The scale was significantly correlated with subjects' level of activity and subjective assessment of their health status. Moderate correlation with health-related hardiness scale also supported the validity. Factor analysis was performed to confirm whether the scale represents the three sub-areas as suggested in the literature. The results of the factor analysis led to a three factor solution according to Kaiser's criterion, but the items were not strongly and cleanly loaded for the third factor. This can be explained in that, among the three sub-ADL areas of the self-efficacy scale, the areas of self care activities and household tasks seem to have similar levels of difficulty in performance with not enough differences for the self-efficacy scale to distinguish between the two areas. Therefore, one factor solution was suggested since ADL can be seen as a unit of activities at similar level of difficulty in performance. One factor solution explained 68.1% of variance of the 19-item scale and all items were correlated over .6 with the factor, showing that the selected factor solution fits the model. The results indicated that the Korean version of Task Self-Efficacy Scale for ADL was reliable and valid in producing useful information to evaluate the effects of various interventions toward promoting health and quality of life for elderly people.

• Journal of the Korea Institute of Building Construction
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• v.5 no.1 s.15
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• pp.75-79
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• 2005

The Korean society faces a new issue of accepting foreign workers. Foreign labors in construction industry reached about 400,000 recently. Thus they have become one of the essential resources to fill up insufficient labor supplies in construction industry. And it is important how to manage foreign labors efficiently. However there are few studies focused on this subject. Purpose of this study is to research productivity of foreign labors in the domestic construction site. So investigate the value of foreign labors. Also this study forecast elements effect on foreign labors productivity in the construction industry. And research what element is more important to improve productivity and what element is more difficult to manage. In the result, this study is expected to prospect effective method of foreign labor's management in the domestic construction industry, so contribute to utilize foreign labors more efficiently.

• Transactions on Electrical and Electronic Materials
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• v.17 no.3
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• pp.134-138
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• 2016

The fullerene solar cells are becoming a feasible choice due to the advanced developments in donor materials and improved fabrication techniques of devices. Recently, sufficient optimization and improvements in the processing techniques like incorporation of solvent vapor annealing (SVA) with additives in solvents has become a major cause of prominent improvements in the performance of organic solar cell-based devices . On the other hand, the challenge of reduced open circuit voltage (V_oc) remains. This study presents an approach for significant performance improvement of overall device based on organic small molecular solar cells (SMSCs) by following a two step technique that comprises thermal annealing (TA) and SVA (abbreviated as SVA+TA). In case of exclusive use of SVA, reduction in V_oc can be eliminated in an effective way. The characteristics of charge carriers can be determined by the measurement of transient photo-voltage (TPV) and transient photo-current (TPC) that determines the scope for improvement in the performance of device by two step annealing. The recovery of reduced V_oc is linked with the necessary change in the dynamics of charge that lead to increased overall performance of device. Moreover, SVA and TA complement each other; therefore, two step annealing technique is an appropriate way to simultaneously improve the parameters such as V_oc, fill factor (FF), short circuit current density (J_sc) and PCE of small molecular solar cells.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.670-674
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• 2012

The photovoltaic performance of solid-state dye-sensitized solar cells employing hole transport material (HTM), 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9'-spirobifluorene (spiro-MeOTAD), has been investigated in terms of HTM overlayer thickness. Two important parameters, soak time and spin-coating rate, are varied to control the HTM thickness. Decrease in the period of loading the spiro-MeOTAD solution on $TiO_2$ layer (soak time) leads to decrease in the HTM overlayer thickness, whereas decrease in spin-coating rate increases the HTM overlayer thickness. Photocurrent density and fill factor increase with decreasing the overlayer thickness, whereas open-circuit voltage remains almost unchanged. The improved photocurrent density is mainly ascribed to the enhanced charge transport rate, associated with the improved charge collection efficiency. Among the studied HTM overlayer thicknesses, ca. 230 nm-thick HTM overlayer demonstrates best efficiency of 4.5% at AM 1.5G one sun light intensity.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.69.2-69.2
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• 2010

Recently, bulk hetero-junction cells have been extensively studied by many researchers. Most of these cells were fabricated by spin coater. However, the spin coating process is not favorable to the large-scaled industry because it is not compatible with roll-to-roll process. One of the alternative methods is Doctor blading. In this study, we fabricated large OPV cells having total area of $100cm^2$. The buffer layer was Poly-(3,4-ethylenedioxythiophene) : poly-(styrenesulfonate) aqueous dispersion (PEDOT:PSS) and the active material is poly (3-hexythiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) blend in the solvent of Chlorobenzene. All of the organic layers were coated by dragging the blade with a speed of 5~20 mm/s on the stage with a temperature of $50^{\circ}C$. As-bladed PEDOT:PSS layer was baked at $120^{\circ}C$ for 10 minutes to eliminate the water. The cell structure is patterned ITO substrate/PEDOT:PSS/P3HT:PCBM/LiF/Al. The topmost electrode, LiF/Al, was deposited by thermal evaporation. After depositing electrode, and the cell was annealed at $150^{\circ}C$ for 30 minutes. The measured ISC, VOC, fill factor, and PCE were 2.95 A, 5.86 V, 0.32, and 0.78%, respectively. PCE was quite low but the large active area could be obtained successfully.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.81-81
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• 2009

Non-sintered Alumina films were fabricated via inkjet printing processes without a high temperature sintering process. The packing density of these inkjet-printed alumina films measured around 60%. Polymer resin was infiltrated thru these non-sintered films in order to fill out the 40% of voids constituting the rest of the inkjet-printed films. The concept of inkjet-printed Alumina-Resin hybrid materials was designed in order to be applicable to the ceramic package substrates for 3D-system module integration which may possibly substitute LTCC-based 3D module integration. So, the dielectric properties of these inkjet-printed $Al_2O_3$ hybridmaterialsareofourgreatinterest. We have measured dielectric constant and dissipation factor of the inkjet-printed $Al_2O_3$-resinhybridfilmsbyvaryingtheamountofresininfiltratedthruthe$Al_2O_3$films.