• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.4
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• pp.47-53
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• 2011

The Electric Multiple Unit (EMU) has many types of door system such as sliding door, plug door etc.al. according to customer's requirements. The sliding door is widely used in Korea but has weak point in the noise problem. In the low operation speed, the noise coming from outer side of the EMU is not an important factor. As the speed is higher than before, noise is increased and make a problem. The main cause of noise is the imperfect air tightness in the EMU. The plug door system has advantages for the noise reduction characteristic in the high speed area. We have been developing electric plug-in door. The door is controlled by Door Control Unit(DCU) following the order of Automatic Train Protection (ATP) that is a kind of train signalling system. DCU has to simultaneously open and close the doors and the operation of it is related to the passengers safety. So DCU is a safety device that is important to reliability and safety. DCU is composed of several devices of control, motor driving, Input/Output, communication and power. In this paper, we will describe the functions, characteristic, requirement, subsystem and test results of DCU used for the electric plug-in door.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.85-91
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• 2002

Even though electroless Hi and Sn-Ag-Cu solder are widely used materials in electronic packaging applications, interfacial reactions of the ternary Ni-Cu~Sn system have not been known well because of their complexity. Because the growth of intermetallics at the interface affects reliability of solder joint, the intermetallics in Ni-Cu-Sn system should be identified, and their growth should be investigated. Therefore, in present study, interfacial reactions between electroless Ni UB7f and 95.5Sn-4.0Ag-0.5Cu alloy were investigated focusing on morphology of the IMCs, thermodynamics, and growth kinetics. The IMCs that appear during a reflow and an aging are different each other. In early stage of a reflow, ternary IMC whose composition is Ni$_{22}$Cu$_{29}$Sn$_{49}$ forms firstly. Due to the lack of Cu diffusion, Ni$_{34}$Cu$_{6}$Sn$_{60}$ phase begins growing in a further reflow. Finally, the Ni$_{22}$Cu$_{29}$Sn$_{49}$ IMC grows abnormally and spalls into the molten solder. The transition of the IMCs from Ni$_{22}$Cu$_{29}$Sn$_{49}$ to Ni$_{34}$Cu$_{6}$Sn$_{60}$ was observed at a specific temperature. From the measurement of activation energy of each IMC, growth kinetics was discussed. In contrast to the reflow, three kinds of IMCs (Ni$_{22}$Cu$_{29}$Sn$_{49}$, Ni$_{20}$Cu$_{28}$Au$_{5}$, and Ni$_{34}$Cu$_{6}$Sn$_{60}$) were observed in order during an aging. All of the IMCs were well attached on UBM. Au in the quaternary IMC, which originates from immersion Au plating, prevents abnormal growth and separation of the IMC. Growth of each IMC is very dependent to the aging temperature because of its high activation energy. Besides the IMCs at the interface, plate-like Ag3Sn IMC grows as solder bump size inside solder bump. The abnormally grown Ni$_{22}$Cu$_{29}$Sn$_{49}$ and Ag$_3$Sn IMCs can be origins of brittle failure.failure.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.2
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• pp.61-67
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• 2017

As transistor density increases rapidly, a heat flux from IC device rises at fast rate. Thermal issues raised by high heat flux cause IC's performance and reliability problems. To solve these thermal management problems, the conventional cooling methods of IC devices were reached their thermal limit. As a result, alternative cooling methods such as liquid heat pipe, thermoelectric cooler, thermal Si via and etc. are currently emerging. In this paper microchannel liquid cooling system with TSV was investigated. The effects of 2 coolants (DI water and ethylene glycol 70 wt%) and 3 metal bumps (Ag, Cu, Cr/Au/Cu) on cooling performance were studied, and the total heat flux of various coolant and bump cases were compared. Surface temperature of liquid cooling system was measured by infrared microscopy, and liquid flowing through microchannel was observed by fluorescence microscope. In the case of ethylene glycol 70 wt% at $200^{\circ}C$ heating temperature, the total heat flux was $2.42W/cm^2$ and most of total heat flux was from liquid cooling effect.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.5
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• pp.357-368
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• 2017

To establish new metal groundwater standard, 5 metals such as aluminum, chromium, iron, manganese, and selenium were evaluated by Chemical Ranking Of groundWater pollutaNts (CROWN) including possibility of exposure, toxicity, interest factor, connection standard for other media, and data reliability. 430 groundwater samples in 2013 and 2014 were collected semiannually from 110 groundwater wells and they were analyzed for selenium, manganese, iron, chromium, and aluminum. For this study, 430 groundwater samples were categorized into 3 geological distribution features, such as igneous, metamorphic, and sedimentary rock region and geological background levels were divided by pre-selection methods. For the results, the average concentrations of aluminum, chromium, iron, manganese, and selenium in 430 groundwater samples were $0.0008mg\;L^{-1}$, $0.0001mg\;L^{-1}$, $0.174mg\;L^{-1}$, $0.083mg\;L^{-1}$, and $0.0004mg\;L^{-1}$, respectively. In addition, among various geologies, average concentration of selenium was the highest in igneous rock region, average concentrations of chromium, manganese and aluminum were the greatest in sedimentary rock region, and average concentration of iron was the most high in metamorphic rock region. As a result of the geological background concentration with pre-selection method, background concentrations of selenium and aluminum in groundwater samples were the highest from sedimentary rock as $0.0010mg\;L^{-1}$ and $0.0029mg\;L^{-1}$ and background concentrations of manganese and iron in groundwater samples were the greatest from metamorphic rock as $0.460mg\;L^{-1}$ and $1.574mg\;L^{-1}$, and no chromium background concentration in groundwater samples was found from all geology.

• Particle and aerosol research
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• v.16 no.2
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• pp.49-59
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• 2020

Various devices have been developed to the measurement of particulate matter pollutants, and Optical Particle Counter (OPC) that can be easily and quickly measured is widely used lately. The measured value by OPC is converted to weight concentration using the correction factor (CF). The calculation of CF is very important to improve the reliability and accuracy of OPC. In this study, the CF calculation study of light scattering laser photometer (model 8533, TSI) was carried out to measure in the atmospheric environment using 2 gravimetric devices and 3 light scattering laser photometer devices. Regression analysis and Tukey tests were used to significance the test of measurement devices. Measurements were carried out twice. There was a comparative analysis of measurement data between light scattering laser photometer and gravimetric devices in 1st measurement, and then the Evaluation of PM2.5 concentration corrected by CF performed in 2nd measurement. As a result of the significance analysis between light scattering laser photometer and gravimetric devices, the correlation between the same method was high, but the correlation between different methods was low. CF was calculated as 0.4258 based on the measurement results, and it is a similar level to previous studies at home and abroad. It is expected that these results can be used as basic data in the future study for air quality measurement research using light scattering laser photometer. Also, in order to improve the accuracy of the measurement techniques and the development of technology in the atmospheric environment, CF calculation research should be conducted continuously.

• Journal of the Korea Society for Simulation
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• v.23 no.1
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• pp.21-31
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• 2014

In this article, data mining simulation is applied to find a proper approach and results of analysis for study of variables related to organization. Also, turnover intention and organizational commitment are used as target (dependent) variables in this simulation. Classification and regression tree (CART) with ensemble methods are used in this study for simulation. Human capital corporate panel data of Korea Research Institute for Vocation Education & Training (KRIVET) is used. The panel data is collected in 2005, 2007, and 2009. Organizational commitment variables are analyzed with combined measure variables which are created after investigation of reliability and single dimensionality for multiple-item measurement details. The results of this study are as follows. First, major determinants of turnover intention are trust, communication, and talent management-oriented trend. Second, the main determining factors for organizational commitment are trust, the number of years worked, innovation, communication. CART with ensemble methods has two ensemble CART methods which are CART with Bagging and CART with Arcing. Comparing two methods, CART with Arcing (Arc-x4) extracted scenarios with very high coefficients of determination. In this study, a scenario with maximum coefficient of determinant and minimum error is obtained and practical implications are presented. Using one of data mining methods, CART with ensemble method. Also, the limitation and future research are discussed.

• Journal of the Korean Geotechnical Society
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• v.29 no.2
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• pp.35-45
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• 2013

The void ratio is an important parameter for reflecting the soil behavior including physical property, compressibility, and relative density. The void ratio can be obtained by laboratory test with extracted soil samples. However, the specimen has a possibility to be easily disturbed due to the stress relief when extracting, vibration during transportation, and error in experimental process. Thus, the theoretical equations have been suggested for obtaing the void ratio based on the elastic wave velocities. The objective of this paper is to verify the accuracy of the proposed analytical solution through the error norm. The paper covers the theoretical methods of Wood, Gassmann and Foti. The elastic wave velocity is determined by the Field Velocity Probe in the southern part of Korean Peninsular. And the rest parameters are assumed based on the reference values. The Gassmann method shows the high reliability on determining the void ratio. The error norm is also analyzed as substitution of every parameter. The results show every equation has various characteristics. Thus, this paper may be widely applied for obtaining the void ratio according to the field condition.

• Journal of Korean Home Economics Education Association
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• v.25 no.2
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• pp.49-63
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• 2013

This study is conducted to activate the education of leisure activity for the old age so as to improve the qualities of the lives in the prolonged elderly lives. The method is examined to see how the level and types of leisure activities and life satisfaction for elderly. The target of the survey for this study was the 280 male and female elderly living in S city and C city. the statistics used for data analysis were reliability, frequency, percentage, mean standard deviation, t-test, one way ANOVA and correlation. The results of study were as follow; First, the result investigating the degrees of old people's participation in the pattern of leisure activities and life satisfaction showed pastime activities and family centered activities as the most participating leisure activity pattern, self developing activities and religious social service activities as the least participating one. Second, in comprehensive social demographic characteristic of the elderly participating in the leisure activities pattern, it was shown that the higher their level of lives was, the better their family atmosphere was, the healthier they were, they participated more in their leisure activities. Third, when the life satisfaction were reviewed to find what relation there were according to the pattern of leisure activities, it was shown that the more they participated in recreation and social activities, the more they participated in self developing activities, the more they participated in family centered activities, their life satisfaction was higher. and the old people who did the pastime activities showed high life satisfaction too. Considering this result, we need to develop systematic programs suited to our culture. In addition, Home Economics Education has to support the ideas and leisure experts have to be cultivated.

• Research in Community and Public Health Nursing
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• v.12 no.1
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• pp.278-287
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• 2001

The purpose of this study is to provide with basic information on application of hand acupuncture as a complementary and alternative therapy by giving some recognition of efficiency and effectiveness of hand acupuncture. And so, answers for questionnaires of 290 respondents were used for this research and collected from June 5 through 13, 1999 from adults twenty and over who were participating in the hand acupuncture training program in Seoul and had some direct experiences with hand acupuncture therapy, whatever they had been treated and/or had treated. To secure reliability of measurement tool. Cronbach'a has been calculated and Factor Analysis was done as Validity Analysis of question classification. Demograprucal characteristics of hand acupuncture experienced people and factors related to hand acupuncture experiences are calculated based on the real number and percentage. The degree of recognition of efficiency and effectiveness of hand acupuncture is made as average and standard deviation, while the degree of recognition of efficiency and effectiveness based on general characteristics come from one-way ANOVA. 1. According to socio-demographical analysis. the questioned could be classified firstly as age (40-49 : 32.5%. 30-39 : 24.9%. 50-59 : 21.9%. 60-69 : 14.7%. 20-29 : 6.0%). secondly gender (male 36.6%. female 63.4%). thirdly occupation (housewife: 43.8%. self-employed: 15.5%. company-employee: 14.8%). fourthly education (high school graduate: 41.9%, college graduate: 37.9%), and lastly monthly-income (1 to 2 million: 51.4%. 2 to 3 million: 20,3%) 2, As for the general aspects related to hand acupuncture. 80,0% of the respondents answered almost zero for the monthly average number of visit to hospital and 15.5% responded 1 to 2 visits, 6,2% of the respondents is complaining of a disorder of digestive system. 19,0% circulatory disease, 10.7% bad nervous system. By utilizing hand acupuncture, 84% of the questioned have following experiences in curing diseases: digestive system 47.3%, circulatory system 9.3%, nervous system 8.3%, 54,1% are curing 1 to 2 and 10.3% 3 to 4 patients on a daily basis with hand acupuncture. Research on the demerits of giving medical treatment with hand acupuncture shows 23,8% are feeling economic burden. 16.6% difficulty of learning and 16.2% weak theoretical backgrounds. 3. Among the efficiency recognition, possibility of general application is average 4,29 and simple treatment is 4,19. economic merits 4.36. possibility of establishment with supplementary and alternative medicine 4.17, medical effectiveness 4.09. 4, As a result of demographical analysis on the efficiency and effectiveness of hand acupuncture therapy, it appears that the recognition of efficiency based on occupation and the recognition of effectiveness based on monthly income are most significant to be noticed. In an orderly fashion. government-employee, self-employed, company-employee. and then housewife have perceived hand acupuncture very efficiently, And those who recognize hand acupuncture to be most effective are people earn 1 million to 2 million won a month, 5. The efficiency(p = .003) and effectiveness (p= .049) of hand acupuncture therapy by number of visit to hospital were statiscally significant, and effectiveness of hand acupuncture therapy by disease exist was statiscally significant (p= .033).

• Journal of Applied Tourism Food and Beverage Management and Research
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• v.16 no.1
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• pp.43-69
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• 2005

Generally, brand is the title for discriminating their own goods and service from other competitive company, brand-image means customer's good and bad affection or loyalty the brand of specific company. Customers often choose the goods according to the value of goods brand. In terms of this viewpoint, the value of company's brand is very important factor to the company's success. Brand-image also effects customers on selling company's goods. Specially, to the hotel business that should ensure lots of customer for a long period with the interest and credit of customers, its brand-image is more significant. What the image is looked upon as a important factor in marketing is due to the difficulty of discrimination against goods standardized in price and quality. Therefore, the company's image acts as a more important marketing factor in the high industrial society. Also it means a lot to the customer's purchasing behavior. When the company's brand-image is recognized or discriminated, customer's memory is longer and customer's reliability is raised than other company's advertisement and public information. Nowadays, most of hotels are perceiving the importance on their own brand-image but in the lack of deep study and systematic strategy in reality. The purpose of this study is to research the effect on customer's purchasing intention of hotel brand-image and choice-attribution. The empirical research has been done from 23April, 2004 to 20May, 2004. Data were collected from general customers who are using hotel located in Taegu. In conclusion, hotel brand-image depends highly on, the service quality of hotel staff and reputation of hotel. Besides, this acts on customer's hotel choice decisively.