• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.1
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• pp.26-32
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• 2007

This study was carried out fusion-welded butt joints in SWS 490A high strength steel subjected to tensile test that load-deflection curve. The windowed or short-time Fourier transform(WFT or STFT) makes possible for the analysis of non-stationary or transient signals into a joint time-frequency domain and the wavelet transform(WT) is used to decompose the acoustic emission(AE) signal into various discrete series of sequences over different frequency bands. In this paper, for acoustic emission signal analysis to use a continuous wavelet transform, in which the Gabor wavelet base on a Gaussian window function is applied to the time-frequency domain. A wavelet transform is demonstrated and the plots are very powerful in the recognition of the acoustic emission features. As a result, the technique of acoustic emission is ideally suited to study variables which control time and stress dependent fracture or damage process in metallic materials.

• Health Policy and Management
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• v.17 no.4
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• pp.31-53
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• 2007

The purpose of a national health care system is to improve health care outcome among population. The objective of the study was to explore the determinants of health outcome in the 24 OECD countries between two health care financing systems. The study employed the pooled time series and cross-sectional analysis with tax-funded and social insurance-funded countries over the period of 1980 to 1999 using OECD Health Data 2002. The study revealed that health expenditure per capita, physicians per 1,000 of the population and calorie intake were positively significantly associated, smoking rate was negatively associated with health outcome while controlling all variables in the tax-funded countries. But in the insurance-funded countries, health expenditure per capita and the number of physicians were not statistically significant factors explaining health outcome. Only the calorie intake was positively associated with, and smoking rate, alcohol consumption per capita, and total nitrogen oxide emission per capita were negatively significantly associated with health outcome. In conclusion, healthy life style factors were much more important to improve health outcome in the both systems.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.186-188
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• 1998

Acoustic emission monitoring on two racetrack superconducting field winding coil was performed during excitation and quenches to diagnose the integrity of the field winding coils. Two field windings were not impregnated with epoxy The results confirm that the acoustic emission signals are mainly due to conductor motions which cause premature quenching of the winding. The quench current of modified racetrack type field winding coil (Type B) are more higher than that of conventional field winding coil (Type A).

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.342-348
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• 2005

This study was carried out fusion-welded butt joints in SWS 490A high strength steel subjected to tensile test that load-deflection curve. The windowed or short-time Fourier transform (WFT or SIFT) makes possible for the analysis of non-stationary or transient signals into a joint time-frequency domain and the wavelet transform (WT) is used to decompose the acoustic emission (AE) signal into various discrete series of sequences over different frequency bands. In this paper, for acoustic emission signal analysis to use a continuous wavelet transform, in which the Gabor wavelet base on a Gaussian window function is applied to the time-frequency domain. A wavelet transform is demonstrated and the plots are very powerful in the recognition of the acoustic emission features. As a result, the technique of acoustic emission is ideally suited to study variables which control time and stress dependent fracture or damage process in metallic materials.

• The Journal of Information Systems
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• v.21 no.1
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• pp.93-116
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• 2012

Internet users' desire to share shopping experiences has resulted in the appearance of the paradigm shift called social commerce, which combines social media with commerce. However, while foreign market realizes social commerce in a various way, current domestic social commerce market still seems to be highly filled with social shopping sites offering 50 percent discount, thus causing concerns about market distortion from a cutthroat competition. In order to overcome the limitations of social commerce remaining in the early stage, and to enhance the communication among consumers, this study conducted an empirical study on the social-commerce business models design based on context. The results of the study brought the imaginary, optimal combination model by conjoint analysis, using the segmented group through cluster analysis. To overcome the uniformity of social commerce and to enhance communication among consumers, the context-based optimal combination model should be proposed as the alternative social commerce business model in the domestic market which remains as a simple group-purchase function. Furthermore, this study will be used as an informative reference designing customer oriented service model for social commerce business.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.3
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• pp.417-429
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• 1998

The advance of the MPEG (Moving Picture Expert Group) and the DSP (Digital Signal Processing) technologies lead the emergence of the information appliances, which are gradually digitalized and embedded the high-speed networking function. However, there are some difficulties in establishing any one specific model, since standardization of the scale and function of home ATM network is being progressed by standardization organizations and no absolute model has been defined. This paper consider topologies for a home ATM network, such a star-type, tree-type, and mesh-type topology, by comparing the structure, functional characteristics and performance. From this analysis we suggest the design method of the home ATM network.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.117-120
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• 2007

개인의 체질에 맞춰 의학적 행위를 시행하는 사상의학은 우리나라 고유의 전통의학으로 가치를 인정받고 있다. 이러한 사상의학에서 가장 중요한 것은 사상체질의 정확한 분류이다. 본 논문에서는 기존의 사상체질 분류 방법인 용모사기, 체형기상, QSCCII, 체질침 등이 임상의들의 직관에 의해 행해지고 있다는 문제점을 해결하기 위해 사상체질 분류의 정량화 및 객관화를 위한 연구를 수행하였다. 이를 위해 본 논문에서는 음성 신호 분석에서 발생하는 정보의 출력값에 의해 사상 체질을 분류하는 방법을 제안하였다. 이를 위해 40대 이상의 장년기 남성을 대상으로 사상체질 전문의의 진단표에서 뚜렷한 특징을 보유하고 있는 집단군을 구성하고 이들의 음성 특성을 분류하여 음성학적 요소를 추출하고자 한다. 또한 출력된 결과값을 토대로 체질 집단별 차이점과 유사성을 분류하여 사상 체질 분류를 행하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.59-62
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• 2007

태어나면서부터 건강에 대한 욕구는 현대 사회에서 많은 부분을 차지하게 된다. 물론 어려서부터의 건강관리가 건강 수명 연장은 물론 가장 기본적인 행복한 삶의 추구까지도 보장되고 있는 실정이다. 이를 위해 본 논문에서는 한의학에서 환자의 질병을 진단하기 위해 사용되고 있는 망진(望診)과 청진(聽診)의 이론적 근거를 바탕으로 소아 감기 질환에 대한 진단 시스템을 개발하고자 한다. 특히 소아감기는 일반적으로 제일 발병률이 높은 질환으로 얼굴 부위에 열을 동반한다는 것과 울음소리가 인체의 모든 조음기관과 연관되어 있다는 한의학적 이론을 기반으로 소아의 생체신호를 분석하여 소아 감기와의 상관성을 분석하고자 한다. 이를 위해 소아 감기 환자에 대한 1차 실험으로 얼굴 영상에서의 열 관련 여부에 대한 색상 분석을 행하였으며 2차 실험으로는 조음기관에 대한 성분음을 추출하는 스펙트럼 분석을 수행하였다. 이를 통해 정상 소아와 감기 질환을 앓고 있는 소아 환자간의 차이점을 추출하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.405-408
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• 2007

건강관리 및 유지에 대한 현대인들의 관심이 증대되면서 삶의 질 향상을 추구하는 고령화 사회에서 성인병 및 만성질환은 매우 위험한 요인이 되고 있는 실정이다. 특히 심장 질환은 3대 사망률 중 한 부분을 차지하고 있을 정도로 위협적이며 비전염성 만성질환 중 하나이다. 그러나 모든 질환에 대한 대처 방법이 동일하듯이 조기 진단에 의한 질환 예방이 무엇보다 중요하다. 따라서 본 논문에서는 심장 질환자의 음성 신호를 획득하여 다양한 음성분석학적 요소 추출 및 분석을 통해 심장 질환과의 연관성을 파악하고자 한다. 이를 위해 본 논문에서는 기존의 음성 분석 요소에 대한 1차 실험을 검증하고 추가 음성 분석 요소들에 대한 2차 실험을 행하여 각각의 분석 요소들과 음성에 대한 형태학적 특징을 시각화하여 편리하게 심장 질환을 진단하는 기법들을 제시하고자 한다.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.214-219
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• 1997

The mechanical seals, which are installed in rotating machines like pump and compressor, are generally used as sealing devices in the many fields of industries. The failure of mechanical seals such as leakage, crack, breakage, fast and severe wear, excessive torque, and squeaking results in big problems. To identify abnormal phenomena on mechanical seals and to propose the proper monitoring parameter for the failure of mechanical seals, sliding wear experiments were conducted. Acoustic emission, torque, and temperature were measured during experiments. Optical microstructure was observed for the wear processing after every 10 minute sliding at rotation speed of 1750 rpm and scanning electron microscopy was also observed. Except for the initial part of every experiment, the variation of acoustic emission was well coincided with torque variation during the experiments. This study concludes that acoustic emission and torque are proper monitoring parameters for the failure of mechanical seals. The intensity of acoustic emission signals is measured in root mean square voltage. Temperature of sealing face will be used as a parallel parameter for increasing the reliability of monitoring system.