• ETRI Journal
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• 제33권5호
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• pp.661-669
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• 2011

In this paper, we propose an efficient soft-output signal detection method for spatially multiplexed multiple-input multiple-output (MIMO) systems. The proposed method is based on the ordered successive interference cancellation (OSIC) algorithm, but it significantly improves the performance of the original OSIC algorithm by solving the error propagation problem. The proposed method combines this enhanced OSIC algorithm with a multiple-channel-ordering technique in a very efficient way. As a result, the log likelihood ratio values can be computed by using a very small set of candidate symbol vectors. The proposed method has been synthesized with a 0.13-${\mu}m$ CMOS technology for a $4{\times}4$ 16-QAM MIMO system. The simulation and implementation results show that the proposed detector provides a very good solution in terms of performance and hardware complexity.

• 전력전자학회논문지
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• 제16권1호
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• pp.79-87
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• 2011

본 논문에서는 웨이블렛(Wavelet) 변환을 이용한 태양광 발전시스템의 고장진단에 관한 연구를 수행하였다. 기존에는 추가적인 하드웨어와 센서를 사용하여 인버터의 고장을 진단하는 방법으로, 단가가 상승하고 사양이 바뀔 경우 재설계를 해야 하는 문제점이 있었다. 제안된 방식은 인버터 전류나 전압과 같은 상태변수들을 다단계 변환을 통해 얻어낸 웨이블렛 계수들의 변화를 감지하여 고장의 종류와 부위를 인식하는 방법이다. 정규화 표준 편차를 이용하여 웨이블렛 계수의 변화로부터 정확하고 신속한 고장 진단이 가능하다. 이 방법은 간단한 계산과 고장 유형을 정확하게 예측할 수 있는 장점이 있다. 컴퓨터 시뮬레이션과 제어기 제작을 통한 실험 결과로서 연구의 타당성을 입증하였다.

• 생약학회지
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• 제20권3호
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• pp.180-187
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• 1989

Systematic pharmacological studies on powdered whole part of unossified antler obtained from Cervus nippon Temminck var. mantchuricus have been carried out in mice and rats. Powdered antler, with a single oral administration, showed a very weak acute and subacute toxicity; its MLD being >5g/kg orally in mice. On daily oral treatments of the antler for 14 days, it did not cause any significant differences in body weight gain, various organ weights and serum transaminase activities compared to those of the control rats. Powdered antler, with a single oral administration, showed a remarkable analgesic activity as evaluated by writhing syndrome and tail-pressure test, a weak CNS depressant activity as well as a weak immunopotentiating action as evaluated by carbon clearance test in mice. Powdered antler, with repeated treatments, showed a moderate antifatigue effect against immobilized stress and showed significant increases in both adrenal weight and its ascorbic acid content in rats, suggesting that the mode of antifatigue effect of antler is related to adrenal and its components.

• Toxicological Research
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• 제21권3호
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• pp.255-261
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• 2005

Gami-Samhwang-San, a herbal prescription for obesity treatment, is composed of seven crude herbs such as Rehmanniae Radix Preparata, Ephedrae Herba, Scutellariae Radix, Acori Gramineri Rhizoma, Polygalae Radix, Typhae Pollen, Armeniacae Semen, Menthae Herba. In this study, marker substances in n-butanol fraction (SH-21-B) from Gami-Samhwang-San were analyzed by high performance liquid chromatography (HPLC) and acute toxicity of standardized SH-21-B was evaluated by good laboratory practices (GLP) guideline of Korea Food and Drug Administration. Therefore we confirmed that there were baicalin of 15.92%, amygdalin of 6.57% and ephedrine of 2.49% in SH-21-B. SH-21-B was administered in rats at dose of 0 mg/kg, 2,000 mg/kg, and 5,000mg/kg. Clinical signs of both sexes of rats were observed daily for 14 days after single oral administration. Two female rats one administered at 2,000 mg/kg and the other administered at 5,000 mg/kg, died, but no dead animal was observed among male rats. Therefore $LD_{50}$ in the female rat is observed to be 8,710 mg/kg, and MLD (Minimun Lethal Dose) of the male rat is observed to be more than 5,000 mg/kg.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권6호
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• pp.1994-2017
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• 2022

In view of the past, the mobility of the multicast source in the mobility networks is seldom discussed in the traditional multicast protocols. It is a heavy cost for the traditional multicast protocols to reconstruct the multicast tree in the Network Mobility (NEMO) environment. This article proposes an alternative multicast protocol, referred to as Mobility-Sensitive Multicast protocol (MSM), for the NEMO environment. The MSM can be considered as an alternative version of the Multicast Listener Discovery (MLD) protocol to maintain the multicast tree in the NEMO. There are two obvious contributions for the MSM. Reconstruct mechanism could rebuild the multicast tree for the mobility of the multicast source. Multi-group suppression mechanism reduce the multicast tree maintaining cost for the mobility of the multicast members. Through the performance evaluations and analyses, the MSM has less cost to maintain the multicast tree than the traditional multicast protocols, especially for a large numbers of multicast groups. Moreover, the MSM allows the mobility of the multicast source to reconstruct the multicast tree easily.

• 적정기술학회지
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• 제5권1호
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• pp.8-17
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• 2019

Solar pumps, for water lift systems, is becoming popular in rural areas for supplying drinking water in dry seasons when its need is elevated. The development in technology has also made solar pumps readily available and cheap which has increased its demands. So, for scattered settlements having a limited budget for operation and maintenance costs, solar pump is preferred over grid connected electrical pumping systems. This primary objective of the study was to design a solar photovoltaic pumping drinking water supply system for a small health post which is about 45 km east from Kathmandu, the capital city of Nepal. The study also compared and verified the final design with the system's existing design prepared by a development agency. The water source for this study was a confined aquifer 115m below the surface. The water demand was calculated to be 11m³ per day. A 1500 kPa submersible pump attached to a motor was selected and installed. Along with that twelve solar panels, reservoir, transmission main and distribution main was designed. The outcomes conclude solar photovoltaic pumping water supply systems to be cost-effective with an estimated cost of only USD 0.84 million per MLD. Solar pumps require low maintenance and operation costs and its repairs can quickly be done by the local people. The study also shows that solar technology produces no sound, needs no fuel making it environmentally friendly.

• 대한전자공학회논문지TC
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• 제42권7호
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• pp.71-78
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• 2005

K-Best 알고리듬은 일정한 최대 복잡도를 가지기 때문에 ML (Maximum Likelihood) 수신기나 sphere decoding 수신기에 비해 실시간 구현에 적합한 알고리듬으로 알려져 있다. 그러나 ML 수신기에 가까운 성능을 내기 위해 충분히 큰 K값을 적용할 경우 여전히 높은 복잡도를 가지게 되며, 구현에 좀 더 적합하도록 작은 K값을 적용할 경우, 최대 복잡도는 낮아지는 반면오차 전달(error propagation)에 의해 높은 SNR 영역에서 에러 플로링(error flooring)이 발생하는 문제점이 있다. 본 논문에서는 이러한 오차 전달 문제를 해결하기 위해 각 레벨 별로 K값을 감소시키는 K-reduction 기법을 제안하였으며, 모의 실험을 통해 연산량 및 비트 오차 확률 측면에서 이득이 있음을 확인하였다.

• The Journal of Advanced Prosthodontics
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• 제10권1호
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• pp.65-72
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• 2018

PURPOSE. The aim of this in vitro study was to investigate the fracture resistance under chewing simulation of implant-supported posterior restorations (crowns cemented to hybrid-abutments) made of different all-ceramic materials. MATERIALS AND METHODS. Monolithic zirconia (MZr) and monolithic lithium disilicate (MLD) crowns for mandibular first molar were fabricated using computer-aided design/computer-aided manufacturing technology and then cemented to zirconia hybrid-abutments (Ti-based). Each group was divided into two subgroups (n=10): (A) control group, crowns were subjected to single load to fracture; (B) test group, crowns underwent chewing simulation using multiple loads for 1.2 million cycles at 1.2 Hz with simultaneous thermocycling between $5^{\circ}C$ and $55^{\circ}C$. Data was statistically analyzed with one-way ANOVA and a Post-Hoc test. RESULTS. All tested crowns survived chewing simulation resulting in 100% survival rate. However, wear facets were observed on all the crowns at the occlusal contact point. Fracture load of monolithic lithium disilicate crowns was statistically significantly lower than that of monolithic zirconia crowns. Also, fracture load was significantly reduced in both of the all-ceramic materials after exposure to chewing simulation and thermocycling. Crowns of all test groups exhibited cohesive fracture within the monolithic crown structure only, and no abutment fractures or screw loosening were observed. CONCLUSION. When supported by implants, monolithic zirconia restorations cemented to hybrid abutments withstand masticatory forces. Also, fatigue loading accompanied by simultaneous thermocycling significantly reduces the strength of both of the all-ceramic materials. Moreover, further research is needed to define potentials, limits, and long-term serviceability of the materials and hybrid abutments.

• 콘크리트학회지
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• 제3권4호
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• pp.79-88
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• 1991

본 눈문에서는 강섬유 혼입에 따른 강섬유보강콘크리트의 강도 중대 현상을 규명하고 파괴에너지를 결정하기 위하여, 일련의 초기균열이 있는 강섬유보강콘크리트 시험체에 대하여 파괴실험을 수행하였다. 파괴실험은 3점 휨 실험법으로 실시하였으며, 실험시 각 시험체의 하중변화에 따른 휨 변형률, 중앙처짐, 균열끝 개구변위와 초기균열 발생시의 하중, 극한하중 등을 조사하였다. 이들 실험 걸과를 토대호 강섬유 혼입량과 초기균열비에 따른 강섬유 보강콘크리트의 파괴인성, 임계 에너지해방률 등을 비교 분석하였으며, 아울러 하중-처짐 선도를 이용한 파괴에너지를 결정하였다. 연구결과, 측정된 강섬유보강콘크리트의 하중-처짐선도는 강섬유 혼입량이 클수록 파괴후 완만하게 나타났으며, 하중-처짐선도 면적에 의하여 계산된 강섬유보강콘크리트의 파괴에너지는 강섬유 혼입량이 0.5%~1.0인 경우에 는 무근콘크리트의 파괴에너지의 약 7~10배, 강섬유 혼입량이 1.5%인경우에는 약 15배 각각 크게 나타났다.

• 한국사회복지학
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• 제64권2호
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• pp.55-83
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• 2012

우리나라 노동시장에서 자영업이 차지하는 비중이 크지만, 자영업내 소득격차도 크다. 그럼에도 아직까지 자영업 소득불평등에 초점을 맞춘 연구가 많지 않다. 이에 본 연구는 한국복지패널 1~4차 자료를 통해, 일반화된 엔트로피지수로 자영업 소득불평등을 측정하고 불평등 요인과 추세를 분해하였다. 분석결과, 첫째, 우리나라 자영업 근로소득 불평등은 매우 높으며, 자영업내 소득양극화가 심각해지고 있었다. 둘째, 자영업 근로소득 불평등의 주된 요인은 고용형태, 교육수준, 연령집단, 사업체규모 그리고 산업으로 나타났다. 셋째, 고용형태에 따른 고용주와 자영자 집단의 상대소득변화효과가 불평 등 증가에 기여하는 정도가 가장 크다. 교육수준과 연령집단, 사업체 규모에 따른 불평등 증가는 집단 내 불평등(순효과) 증가의 기여도가 가장 크고, 집단구성의 변화효과도 불평등 악화에 기여한 것으로 나타났다.