• The Journal of the Acoustical Society of Korea
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• v.30 no.1
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• pp.42-48
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• 2011

This preliminary study is about the application of the compound source to the active noise barrier system as control sources. A compound source is composed of two monopole sources but having opposite phase. However, both monopole sources in one compound source are not independently controlled. The source strength of monopole source close to the noise source is proportional to the other one. Therefore, the cost for the hardware system is cheaper than usual system but known to possibly having a similar performance in generating anti-noise acoustic field. In this study, using a simple active noise barrier system model having a non-reflective floor, the effectiveness of the system with compound sources is investigated through computer simulations and shows 30~40 % performance improvement of noise reduction.

• Journal of Physiology & Pathology in Korean Medicine
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• v.30 no.2
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• pp.116-123
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• 2016

This study was performed to develop questionnaire of cold-heat pattern identification(PI) based on usual symptoms for general people, and we analyzed reliability of the questionnaire. We reviewed cold-heat PI questionnaire of advanced research and selected twenty-three items through three time experts meeting. Three hundred and fifty nine healthy subjects were joined in this study. As a results, Cronbach's α of cold-heat PI questionnaire was 0.79 and 0.83. According to the factor analysis about fifteen-chosen cold-heat PI questionnaires, each cold-heat consisted of two factors and each Convergence was 56.46% and 65.93%. Intra-class Correlation Coefficient was 0.67-0.83. Based on the median of samples of primary source, we classified subjects into four category as Cold, Heat, No Cold-Heat, and Cold-heat complex. We examined agreement of diagnosis and coefficient of kappa, and agreement rate of diagnosis was 64.2%, and coefficient of kappa was 0.51. Based on research result, we expect that validity study about questionnaire of cold-heat PI based on usual symptoms will be continued, and hope to be used as subsidiary diagnosis in clinical practice.

• Journal of environmental and Sanitary engineering
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• v.17 no.2
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• pp.71-78
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• 2002

This study was conducted to evaluate the concentration distribution characteristics of air pollutants by the yellow sand from China. The concentrations and chemical properties of FPM contained in the yellow sand were compared with those of air pollutants when having no yellow sand in order to estimate the variation characteristics and the originated source of air pollutants moved by yellow sand. The concentrations of PM-2.5 and PM-10 contained in the yellow sand showed an increase of 2.3 to 2.7 times than usual, and the concentrations of NO2 and SO2 in the gaseous pollutants showed an increase of about 1.6 times by yellow sand, and thus the air contamination was much influenced by yellow sand phenomenon. The concentrations of inorganic elements contained in FPM from the yellow sand showed a higher concentration variation in the order of Al>Mg>Zn>Pb than usual. The concentration coefficient of air aerosol during the yellow sand period showed that Na, K, Ca, Mg and Fe were originated from natural source, and Pb, Cr, Cd, Cu and Zn were originated from artificial source for inorganic elements. The correlation analysis between FPM and inorganic elements showed in the descending order of Al>K>Pb>Mg, and thus the deposited amount of Pb was influenced by that of yellow sand. The average concentrations of PM-10 measured during the yellow sand period exceeded the Korea Air Environmental Standard and showed a excess rate of 3.4 times in the maximum but the average concentrations of PM-2.5 showed within the United States Air Environmental Standard.

• Journal of Mechanical Science and Technology
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• v.19 no.8
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• pp.1611-1620
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• 2005

This paper shows the use of wavelet transformation combined with inverse acoustics to reconstruct the surface velocity of a noise source. This approach uses the boundary element analysis based on the measured sound pressure at a set of field points, the Helmholtz integral equations and wavelet transformation for reconstructing the normal surface velocity field. The reconstructed field can be diverged due to the small measurement errors in the case of nearfield acoustic holography (NAH) using an inverse boundary element method. In order to avoid this instability in the inverse problem, the reconstruction process should include some form of regularization for enhancing the resolution of source images. The usual method of regularization has been the truncation of wave vectors associated with small singular values, although the order of an optimal truncation is difficult to determine. In this paper, a wavelet transformation is applied to reduce the computation time for inverse acoustics and to enhance the reconstructed vibration field. The computational speed-up is achieved, with solution time being reduced to $14.5\%$.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.862-863
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• 2007

In this article, we researched the characteristics of heat transfer of the bimetal for over-current protection device. Bimetal consists of two metals which have a different thermal expansion coefficient. To analyze the heat transfer characteristics, by using a bimetal which has a single metal, we analyzed the temperature distribution when bimetal acts a switch. As usual, heat source is applied to the bimetal. But, in the over-current protection switch, the current become heat source. So, by using the current as source, we performed the magnetic analysis and thermal analysis together.

• Health Policy and Management
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• v.16 no.4
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• pp.48-67
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• 2006

The aim of the study was to examine levels of satisfaction with health care in North Korea and to identify factors associated with it using a convenience sample of North Korean refugees in China. Data from the 2004 Survey of Health Seeking Behavior of North Korean Households conducted by the Center for Refugee and Disaster Response, Johns Hopkins Bloomberg School of Public Health were used. The study subjects were 273 North Korean refugees whose length of stay in China was less than 3 months. Factor analysis was used to extract factor dimensions from the 12 satisfaction items. Bivariate (t test and ANOVA) and multiple regression analyses were used in examining factors associated with satisfaction with health care use in North Korea Overall, satisfaction level was low ($2.36{\pm}0.36$, score range: 1-5). Of the three-factor dimensions, physician skills scored the highest $(2.93{\pm}0.36)$, followed by drug availability $(2.51{\pm}0.07)$ and general cleanliness $(1.66{\pm}0.55)$. In the multiple regression analysis, having a usual source of care was significantly associated with patient satisfaction. Respondents who identified primary care (section) doctors as their usual source of care tended to be less satisfied than those with the city or county hospital as their usual source of care. County residents tended to report a lower degree of satisfaction with general cleanliness than city residents. Among socioeconomic characteristics, the number of household assets positively predicted satisfaction with drug availability. North Korean residents appear to be dissatisfied with their medical care. It may reflect some inadequacies in the North's universal health care system to meet the healthcare needs of its people.

• Journal of Chest Surgery
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• v.22 no.3
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• pp.483-493
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• 1989

Echinococcal or hydatid cyst is one of the most important zoonoses and commonly seen throughout the world, especially sheep and cattle raising areas, but rare in Korea. The causative organism, Echinococcus granulosus, is a small tapeworm and dogs are the usual source of infestation. Lung is the second most common focus for this disease, after liver. Recently, with increasing numbers of Koreans visiting to those endemic countries especially Middle East, the reports of hydatidosis are increasing. Authors experienced two cases of pulmonary hydatid cyst in the 31 year old male and 44 year old male who had a history of spending 2 * 3 years in Middle East. we found them in incidental routine chest X-ray.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.848-850
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• 2002

Single phase induction motor is directly used usual source, it can be a source of an appliance such as mechanical fan, refrigerator, washing machine, etc. Especially capacitor-run single phase induction motor is suitable to make more inexpensive and high efficient products because it is more high efficiency, and good to start than other single phase induction motors. Generally, voltage and current of capacitor-run single phase induction motor transfer to the part of positive phase and negative phase based on two motor theory. In this paper, we simulate the torque characteristics to capacitance variation from single phase induction motor's equivalent circuit. Through the test using the real motor, we compare and investigate the maximum torque of run state related with capacitance and the adequacy of the converted model.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.107-109
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• 2003

Single phase induction motor is directly used usual source, it can be a source of an appliance such as mechanical fan, refrigerator, washing machine, etc. Especially capacitor-run single phase induction motor is suitable to make more inexpensive and high efficient products because it is more high efficiency, and good to start than other single phase induction motors. Generally, voltage and current of capacitor-run single phase induction motor transfer to the part of positive phase and negative phase based on two motor theory. In this paper, we simulate the torque characteristics to capacitance variation from single phase induction motor's equivalent circuit. Through the test using the real motor, we compare and investigate the maximum torque of run state related with capacitance and the adequacy of the converted model.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.7
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• pp.43-48
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• 2008

The characteristics of heat transfer of the bimetal disc for over-current protection device is specified. Bimetal consists of two metals which have a different thermal expansion coefficient. To analyze the thermal characteristics, temperature distribution when bimetal acts as a switch is calculated. As usual, heat source is applied to the bimetal and electric current is heat source in the over-current protection switch. In this paper, thermal distribution are obtained by solving a coupled electro-thermal field with 3D finite element method.