• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.791-800
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• 2010

Recently wireless sensor networks as a field of ubiquitous computing technology was in the limelight. To use and collect the necessary information, Sink node mobility is essential. TTDD(Two-Tier Data Dissemination) proposed most common technique associated with Mobile sink node in wireless sensor networks, but issues exist that the use of many control packet falls into the energy efficiency. The technique for solving problems is Cluster-Based Energy-efficient Routing protocol (CBPER). But CBPER does not transmit the data correctly to sink node or source node. In this paper, we propose An Energy-Efficient Routing Protocol based on Static Grid using mobile sink nodes in order to solve the data transmission failure and reduce the energy consumption in Wireless Sensor Networks. We have evaluated it with the NS-2 simulator. Our results show that the proposed protocol saves the energy consumption up to 34% in comparison with CBPER. We also prove that the proposed protocol can transmit more accurate data to the sink de than CBPER.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.60-66
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• 2001

Because of internal voids in insulators give rise to partial discharge(PD), which cause local breakdown and even entire insulation breakdown. Treeing due to PD is one of the main causes of breakdown of the insulating materials and reduction of the insulation life. Therefore the necessity for establishing a method to diagnose the aging of insulation materials and to predict the breakdown of insulation has become important. From this viewpoint, our studies diagnose insulation degradation using the method of computer sensing system, which has the advantages of PD and acoustic emission(AE) sensing system. To use advantages of these two methods can be used effectively to search for treeing location and PD in some materials. In analysis method of degradation, We analyzed the PD pulse and AE pulses by regression analysis, compared to these obtained the correlation coefficient and determination coefficient by T-distribution and saw that PD and AE pulses show a similar pattern on the whole. This is in agreement with the results of the research by Yoshimura and Fujita.

• Journal of Aquaculture
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• v.6 no.3
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• pp.187-197
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• 1993

Studies related to water quality in catfish ponds were conducted on commercial catfish production ponds and compared with its receiving streams' water quality in central and west-central Alabama. The ponds were stocked with 10,000 fish/ha. The ponds were aerated nightly (0000-0600 hrs). Fish were fed to satiation at about the same time, six-days a week. In order to assess the pollutional strength of effluents from commercial channel catfish ponds, water samples were collected during each calender season from fall 1990 through summer 1991, and selected water quality variables were monitored. Mean values for water temperature, dissolved oxygen concentration, pH, settleable solids, total suspended soilds, volatile solids, total phosphorus, soluble reactive phosphate, biochemical oxygen demand, total ammonia nitrogen, nitrite, nitrate, and total Kjeldahl nitrogen were basically the same (P> 0.05) between samples taken from the surface and near the bottom. Concentrations of most water quality variables of catfish ponds were higher than those of receiving streams, and especially it had much higher average concentrations of nitrogen and phosphorus than streams.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.74-74
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• 2010

모바일 정보통신기기를 중심으로 전자패키지의 초소형화, 고집적화를 위해 플립칩 공법의 적용이 증가되고 있는 추세이다. 플립칩 패키징 접합소재로는 솔더, ICA(Isotropic Conductive Adhesive), ACA(Anisotropic Conductive Adhesive), NCA(Non Conductive Adhesive) 등과 같은 다양한 접합소재가 사용되고 있다. 최근에는 언더필을 사용하는 플립칩 공법보다 미세피치 대응성을 위해 NCP를 이용한 플립칩 공법에 대한 요구가 증가되고 있는데, NCP의 상용화를 위해서는 공정성과 함께 신뢰성 확보가 필요하다. 본 연구에서는 LDI(LCD drive IC) 모듈을 위한 COF(Chip-on-Film) 플립칩 패키징용 NCP 포뮬레이션을 개발하고 이를 적용한 COF 패키지의 신뢰성을 조사하였다. 테스트베드는 면적 $1.2{\times}0.9mm$, 두께 $470{\mu}m$, 접속피치 $25{\mu}m$의 Au범프가 형성된 플리칩 실리콘다이와 접속패드가 Sn으로 finish된 폴리이미드 재질의 flexible 기판을 사용하였다. NCP는 에폭시 레진과 산무수물계 경화제, 이미다졸계 촉매제를 사용하여 다양하게 포뮬레이션을 하였다. DSC(Differential Scanning Calorimeter), TGA(Thermogravimetric Analysis), DEA(Dielectric Analysis) 등의 열분석장비를 이용하여 NCP의 물성과 경화거동을 확인하였으며, 본딩 후에는 보이드를 평가하고 Peel 강도를 측정하였다. 최적의 공정으로 제작된 COF 패키지에 대한 HTS (High Temperature Stress), TC (Thermal Cycling), PCT (Pressure Cooker Test)등의 신뢰성 시험을 수행한 결과 양산 적용 가능 수준의 신뢰성을 갖는 것을 확인할 수 있었다.

• Congress of the korean instutite of fire investigation
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• 2010.12a
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• pp.63-79
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• 2010

It is found to the arc trace on the junction termination of 345kV cable. According to the analysis of the cable material is judged to be good. Manufacturing and design problems are not considered. In construction defects, it was estimated to the low level of insulation oil. In the majority of the arc trace appeared XLPE is found. However, there is no Soots mark, yellow band has not been confirmed, not associated with a radial arc of the spider leg is not evidence. In other opinions, void, contamination or jut are not found on the inside of XLPE. Thus, by the attachment of the impurities in surface of XLPE insulation is judged to the breakdown.

• Fire Science and Engineering
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• v.14 no.3
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• pp.1-5
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• 2000

In this paper, we analyzed the fire hazard of the ballast for fluorescent lamp used as the indoor lighting. In the result of being analyzed the ballast wire by stereo microscope, many melting points were discovered, it was impossible to judge a cause with the naked eye. In the Thermal-deteriorated ballast wire, elongation structure disappeared at above $700^{\circ}$, and it only showed the enlarged appearance of the copper particle. On the metallurgical microscope of short wire, as it was confirmed the regulation of the columnar structure and the void growth at the center of boundary-face, we found that electrical short-circuit generated. Also, it was confirmed the melted part on the analysis using SEM(scanning electron microscope). Not only CuL and Cuk line that is composition factor of copper but also OK line was observed uniformly on the spectra analysis using EDX(energy dispersive x-ray spectroscopy). It means that oxygen took part in reaction at the recombination process.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.1
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• pp.39-45
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• 1999

Because of internal voids in insulators give rise to partial discharge(PD), which cause local breakdown and even entire insulation breakdown. Treeing due to PD is one of the main causes of breakdown of the insulating materials and nrluction of the insulation life. 1berefore the necessity for establishing a rrethod to diagnose the aging of insulation materials and to predict the breakdown of insulation has becorne irrportant. From this viewpoint, our studies diagnose insulation degradation using the rrethod of computer sensing system, which has PD and acoustic emission(AE) sensing system. To use advantages of these two methods can be used effectiveiy to search for treeing location and PD in sorre materials. In analysis rrethod of degradation, we analyzed the PD and AE pulses by regression analysis, corrpared to these obtained the correlation coefficient and retermination coefficient by T-distribution and saw that PD and AE pulses show a similar pattern on the whole. This has a similar teIlrency to the results of the research by Yoshimura and Fujita.Fujita.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.86-92
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• 2017

The possibility to development of floor vibration problem is larger in case of long span structure under service loads. Therefore, to improve the vibration performance of the floor, increasing of its thickness is a common method. But, increasing of thickness can lead to increase of slab self weight and reduce the effectiveness of the building. For this reason, attention for voided slab which reduces the self-weight is increasing. Hence, voided deck slab combined with deck plate and polystyrene void foam which has buoyancy prevention capacity and much developed construct ability has bee developed. By using the developed voided slab, vibration performance of a mock-up building structure has been investigated in the current study. The results according to analysis showed that they can be implemented in living and bedroom which are considered as 1st grade on the basis of "Residential Evaluation Guidelines for Vibration of Buildings" by the Architectural Institute of Japan.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.6
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• pp.911-917
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• 2008

In this study, we reported the effect of porcine pancreas lipase treatment in the presence of a calcium chloride and Triton X-100 on moisture regain and wettability of PET fabrics. The moisture regain of PET fabrics in the presence of 0.5% surfactant showed a 1.5-fold decrease, compared to the absence of it. Triton X-100 acted as an inhibitor to porcine pancreas lipase hydrolytic activity. The moisture regain and wettability of porcine pancreas lipase treated PET fabrics improved when more than 10mM of calcium chloride was added to the treatment solution. Porcine pancreas lipase treatment caused voids and cracks on PET fabrics.

• KIISE Transactions on Computing Practices
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• v.21 no.9
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• pp.596-603
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• 2015

A concept network is an essential knowledge base for semantic search engines, personalized search systems, recommendation systems, and text mining. Recently, studies of extending concept representation using external ontology have been frequently conducted. We thus propose a new way of building 3-dimensional text model-based concept networks using the world knowledge-level Wikipedia ontology. In fact, it is desirable that 'concepts' derived from text documents are defined according to the theoretical framework of formal concept analysis, since relationships among concepts generally change over time. In this paper, concept networks hidden in a given document collection are extracted more reasonably by representing a concept as a term-by-document matrix.