• Journal of the Korean Society of Safety
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• v.30 no.4
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• pp.106-112
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• 2015

For the construction safety manager, it is expected that job stress is significantly high due to lack of expertise about new technology, new construction methods, and enlargement of scale as well as due to work intensity and unstable work hours. It is probable that such an increase in job stress not only has bad effects on individual, but also the bad effects spread to construction industry at large, resulting in rise in accident rate, increase in direct and indirect loss cost, and loss of reputation. In this context, methods for controlling construction safety manager's job stress are needed at the levels of both government and company. Therefore, this study investigated and analyzed the effects of construction safety manager's job stress on job satisfaction and job commitment, and proposed methods for relieving job stress. In addition, this study was suggested policies for higher job satisfaction and job commitment at the levels of the government and companies.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.291-294
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• 2007

Countries in the world are setting up policies to implement anti-global warning measures to actively cope with the Agreement on Climate Change. Rising problems related to energy and environment prompted research and development efforts to highly efficient electric instrument and environmentally friendly products to secure resources and save energy Korea's high dependency on imported energy and its lack in natural resources make it urgently necessary to develop energy efficient instrument and equipment that can save energy. Every household now uses a transformer, which is very important instrument among others. A variety of technologies to manufacture transformers are currently used along with efforts to develop new materials. Development nit of high efficient transformers is called for by the time and has direct economic impact on suppliers and consumers. In addition, it is desirable to install a transformer that is trustworthy, secure, low on loss, anti-incident capable, small, anti-flammable, environmentally friendly, cost-efficient high-frequency resistant and easy for maintenance. To do this, it is necessary to look deeper into a highly efficient transformer that can save energy. This paper will discuss the types and characteristics of various transformers and propose ways to save energy and raise efficiency tv analyzing a environmentally friendly amorphous transformer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.2
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• pp.165-175
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• 2001

In this paper, it is analyzed lumped element isolators analytically by the analysis program using scattering matrixes including ferrite saturation magnetization, external direct current magnetic field and strip line length and width, designed and experimented the small isolator of mobile phone. The simulation results show that the characteristics of the isolator are affected by external R, C, length and width of strip line and ferrite width and saturation magnetization sensitivity. We proposed the isolator specification applied cellular and PCS mobile phones, experimented the isolator for cellular mobile phones. From the experimented result, isolation and return loss are measured below 20 dB, insertion loss is below 0.7 dB, bandwidth is about 44 MHz at center frequency 836.5 KHz. The implemented isolator has better performances than the conventional one.

• Journal of the Korean Society of Costume
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• v.51 no.3
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• pp.5-18
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• 2001

The purpose of this study is to suggest size specifications for the development of mastectomy bras and breast prostheses. To collect anthropometric data, 250 middle aged women's body measurement were taken and the data were analyzed by statistical methods such as ANOVA, correlation analysis, factor analysis and cluster analysis. The results of the analysis of measurement data showed that lengths. breadths, depths, circumferences are increased significantly when getting older. The results of the correlation analysis showed that there was no direct linear relationship between chest circumference and cup size. From 29 measurements, 4 factors were selected as key factors by the tractor analysis and the breast type were classified into 2 groups by cluster analysis. To set up sizing systems for the mastectomy brassiere, chest circumference and cup size were selected and the loss function was used to decide Intervals of each of them. 6 sizes from chest circumference and 4 sizes from cup sizes were picked, Breast breadth, breast length and breast height were chosen to establish sizing systems for the breast prosthesis. To decide intervals of each of them, the loss function was used and 8 sizes from composition of the 3 factors were picked.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.7
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• pp.799-804
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• 2014

To combine to the power transmission, photovoltaic inverter is demanded, because the photovoltaic system is generated direct current power. However, photovoltaic inverter is sensitive to high temperature. In the temperature rising such as at noon and on summer, efficiency of machine is decreased due to the loss increment. Because this problem causes national energy loss according to the expanding the photovoltaic industry, countermeasure is demanded. There, in this paper, we installed a cooling system using a thermoelement regardless of the temperature. Also, we analyze the cooling effect according to the position of two fans which improve the effect maximize.

• Journal of Korean Neurosurgical Society
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• v.40 no.6
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• pp.455-458
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• 2006

The incidence of blindness after aneurysm surgery is very rare. We experienced a case of unilateral blindness after internal carotid artery[ICA] aneurysm wrapping. A 43-year-old male immediately developed ipsilateral ocular pain and visual loss in his left eye after the treatment of a lateral ICA aneurysm by wrapping with muscle pieces. He had also multiple aneurysms, which were multilobulated anterior communicating artery [A-com], middle cerebral artery[MCA] and posterior communicating artery [P-com] aneurysms. Coilings were done for a part of A-com artery aneurysm and P-com artery aneurysm on admission. The remaining A-com artery aneurysm was clipped and ICA aneurysm was wrapped with temporal muscle piece. A retrobulbar optic neuropathy might have resulted from either direct injury or damage to small dural vessels of the posterior optic nerve. Actually, the optico-carotid space was tight and the optic nerve was compressed by swollen muscle piece. Despite releasing of compression of the optic nerve on second day, his visual loss was irreversible.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.11
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• pp.1054-1062
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• 1991

In this paper a communication system using direct sequence spread spectrum (DS/SS) technique is constructed to transmit burst format data over power line channel with impulsive noise and narrowband interferences. Fast code synchronization is acquired by digital matched filter and data decision is accomplished by sampling pulses. In order to examine the performance of the power line communication system, but error rate and packet loss rate are measured over the simulation channel with various noise sources. When the packet composed of 1-bit preamble and 63-bit data is transmitted under very high burst impulsive noise, the bit error rate is about 10$^3$-10$^4$ and the packet loss rate is below 0.07.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.1-7
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• 2008

This paper presents electromagnetic interference(EMI) suppression method applied on the direct current(DC) motor driver for power tail gate control. EMI noise is generated by the fast switching of power devices connected to electric loads. It has become a matter of concern because of the vast increase in the number and sophistication of electronic system in automotive environment. The proposed EMI reduction method is based on the principle of reducing the transient speed of power devices by changing the parameters of the driver circuit related to the power MOSFET. In this paper, power losses were calculated by loss equations and thermal simulation was used to evaluate the effect on printed circuit board. Based on these results, the DC motor driver was fabricated and tested. The proposed method can help to design a DC motor driver which allows it to obtain an acceptable compromise between power losses and EMI.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.577-583
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• 2010

In this study, the effect of void formation resulting from gas hydrate dissociation or loss of some particles within soil structure on the strength of soil is examined. Beag-ma river sands with uniform gradation were used to simulate a gas hydrate bearing or washable soil structure. Empty capsules for medicine are used to mimic large voids, which are bigger than soil particle. Beag-ma river sand was miced with 8% cement ratio and 14% water content and compacted into a shear box. The number and direction embedded into a specimen. After 4 hours curing, a series of direct shear test is performed on the capsule embedded cemented sands. Shear strength of cemented sands with capsules depends on the volume and direction. The volume and direction formed by voids are most important factors in strength. A shear strength of a specimen with large voids decreases up to 39% of a specimen without void. The results of this study can be used to predict the strength degradation of gas hydrate bearing sediments after dissociation and loss of fine particles within soil structure.

• Journal of Electrochemical Science and Technology
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• v.11 no.4
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• pp.392-398
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• 2020

Producing solar grade silicon using an inexpensive method is a key factor in lowering silicon solar cell costs; the direct electrochemical reduction of SiO₂ in molten salt is one of the more promising candidates for manufacturing this silicon. In this study, SiO₂ granules were electrochemically reduced in molten CaCl₂ (850℃) using Ag-Si eutectic droplets that catalyze electrochemical reduction and purify the Si product. When Ag is used as the working electrode, the Ag-Si eutectic mixture is formed naturally during SiO₂ reduction. However, since the Ag-Si eutectic droplets are liquid at 850℃, they are easily lost during the reduction process. To minimize the loss of liquid Ag-Si eutectic droplets, a cylindrical graphite container working electrode was introduced and Ag was added separately to the working electrode along with the SiO₂ granules. The graphite container working electrode successfully prevented the loss of the Ag-Si eutectic droplets during reduction. As a result, the Ag-Si eutectic droplets acted as stable catalysts for the electrochemical reduction of SiO₂, thereby producing one-dimensional Si rods through a mechanism similar to that of vapor-liquid-solid growth.