• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권6호
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• pp.647-666
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• 2009

Multiple-input multiple-output (MIMO) multiplexing is an attractive technology that increases the channel capacity without requiring additional spectral resources. The design of low complexity and high performance detection algorithms capable of accurately demultiplexing the transmitted signals is challenging. In this technical survey, we introduce the state-of-the-art MIMO detection techniques. These techniques are divided into three categories, viz. linear detection (LD), decision-feedback detection (DFD), and tree-search detection (TSD). Also, we introduce the lattice basis reduction techniques that obtain a more orthogonal channel matrix over which the detection is done. Detailed discussions on the advantages and drawbacks of each detection algorithm are also introduced. Furthermore, several recent author contributions related to MIMO detection are revisited throughout this survey.

• 한국치위생학회지
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• 제14권5호
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• pp.617-622
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• 2014

With the explosive increase of esthetic demands by patients, many dental materials for the esthetic restoration have been introduced. Recently, zirconia based restorations are using for the cases of single crown, bridges, implant prostheses etc. Zirconia have superior mechanical properties and biocompatibility. Owing to the properties of high strength, zirconia has to be manufactured by CAD/CAM system. Dental CAD/CAM system is a futuristic treatment and technical system which makes it possible to produce the precision and uniform prosthesis and also standardize the treatments. This article introduces the characteristics of zirconia, fabrication procedure using CAD/CAM system and procedure for the cementation of zirconia based restoration.

• 마이크로전자및패키징학회지
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• 제25권4호
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• pp.25-34
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• 2018

In this paper, we review the latest technical progress and commercialization of stretchable interconnectors, stretchable strain sensors, and stretchable substrates for stretchable electronics. The development of stretchable electronics can pave a way for new applications such as wearable devices, bio-integrated devices, healthcare and monitoring, and soft robotics. The essential components of stretchable electronic devices are stretchable interconnector and stretchable substrate. Stretchable interconnector should have high stretchability and high electrical conductivity as well as stability under severe mechanical deformation. Therefore several nanocomposite-based materials using CNT, graphene, nanowire, and metal flake have been developed. Geometric engineering such as wavy, serpentine, buckled and mesh structure has been well developed. Stretchable substrate should also pose high stretchability and compatibility with stretchable sensing or interconnecting material. We summarize the recent research results of new materials for stretchable interconnector and substrate as well as strain sensors. The Important challenges in development of the stretchable interconnector and substrate are also briefly discussed.

• 한국환경과학회지
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• 제19권12호
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• pp.1343-1354
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• 2010

The purpose of the study was to analyze the persistence of HCH in atmosphere, soil, sediment and water of the western and southern regions of Korea. The samples from the western region were collected from Anmyeon Island, and the samples from the southern region were collected from Kimhae and Busan. The concentration of HCH isomers in atmosphere showed the pattern of $\alpha$-HCH>$\gamma$-HCH>$\beta$-HCH. The regions with high HCH concentration in the atmosphere are the regions that have been highly exposed to HCH used in the past, and the areas that have been influenced by the long range transport. The HCH that persists in the soil, water and sediment evaporates into the atmosphere, showing the characteristics of Air-Surface exchange. When the regional concentration distributions are compared, the concentration of HCH was higher in the atmosphere of a plain and the cities near the plain, than the urban areas. In this study, the ratio of $\alpha/\beta$-HCH was used as an indicator for estimating the source of Technical HCH and Lindane. According to the result, the contribution of Lindane was high in Kimhae plain and Kimhae urban areas. However, in Busan, the contribution of Technical HCH was higher than Lindane. In case of Anmyeon Island, the western region of Korea had high contribution from Tehcnical HCH. In soil and sediment, $\beta$-HCH was dominant. In water, $\gamma$-HCH was dominant among other isomers. Such results are due to $\gamma$-HCH inLindane. Furthermore, the source of $\gamma$-HCH in urban areas is assumed to be the use of medicine, medical supplies and other living supplies. Based on the results of this study, the management of HCH, a newly list up emerging POPs, should be strengthened by further research on sources, fate, persistency, accumulation and exposures and etc. to the risk assessments.

• 대한조선학회논문집
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• 제60권3호
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• pp.175-185
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• 2023

Many small vessels such as fishing boats operate in the world's oceans; accordingly, interest in these small vessels' exhaust-gas problem is increasing. Research on the application of electric-propulsion technology has been steadily conducted; however, the subject is limited to research ships or leisure boats, while research on application efficiency remains insufficient. This study attempts to apply lithium-battery electric-propulsion technology to small ships. A gross tonnage of 9.77, a representative fishing boat, is to be redesigned as a fully electrified ship. Without changing the main cabin's dimensions and fuel tanks, the ship's propulsion system is redesigned based on a lithium-battery electric-propulsion system. In addition, the redesigned system is compared with the original sample ship's diesel-propulsion system for application-effect analysis. The results indicate that under controlled sailing conditions, the weight and volume of the electric-propulsion system are 9.5 and 10.5 times those of the diesel-propulsion system, respectively. These values indicate that the system cannot meet fishing boats' high endurance requirements. Therefore, under the existing technical conditions, applying the full lithium-battery electric-propulsion system to solve the problem of high emissions from fishing boats shows limited feasibility.

• 융합정보논문지
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• 제9권12호
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• pp.302-312
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• 2019

본 연구는 미용사(메이크업) 국가기술자격증 응시 경험자 및 취득자 220명을 대상으로 자격증 취득을 위한 교육인식 하위요인(필요성, 효용성, 가치, 비용, 적절성)이 현장활용성 및 만족도에 미치는 영향과 각 요인간의 상관관계를 분석하였다. 메이크업자격증 실기 과정 중 활용도 높은 종목은 뷰티메이크업으로 선택하였다. 자격증 교육인식에서 필요성이 높게 나타났고 비용, 연간 시험 횟수에 대한 인식이 낮게 나타나 개선이 필요한 것을 알 수 있었다. 현장활용성에서 뷰티메이크업 활용을 높게 인식하였고 자격증 취득에 대해서 높게 만족하였으며 급여에 대해서는 낮게 인식되었다. 국가기술자격증 교육인식 하위요인 중 필요성, 비용, 적절성이 현장활용성과 만족도에 유의한 정(+)의 영향을 미쳤고 그 중 적절성이 현장활용성에, 비용이 만족도에 가장 큰 영향을 미치는 것으로 나타났다. 따라서 메이크업 자격증 분야의 세분화 및 전문화와 취득을 위한 비용 절감 및 활용성이 높은 이론 및 테크닉 개선을 위한 노력이 필요하다.

• 조명전기설비학회논문지
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• 제29권1호
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• pp.121-127
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• 2015

Recently, LVDC(Low Voltage Direct Current) has been came into the newly spotlight with HVDC(High Voltage Direct Current) and as increasing digital load, DC power supply and high quality of demand is also getting extended. In accordance with the report of EPRI(Electric Power Research Institute), they expect digital load will grow to 50% of whole load in 2020. Subsequently, the use of DC equipment will grow dramatically. Therefore, the careful adoption of LVDC standardization policy is urgently required for the safety of people, prevention of confusion and occupancy of the market.

• 한국수소및신에너지학회논문집
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• 제34권4호
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• pp.327-333
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• 2023

The water gas shift reaction was carried out using the commercial catalyst pellet and the simulated gases expected to occur from waste plastic gasification. In the water gas shift reaction, the high temperature shift reaction and the low temperature shift reaction were continuously performed with CO:H₂O ratio of 1:2, 1:2.5, and 1:3, and the CO conversion and H₂ increase rate were evaluated. The H₂ increase rate increased in order to CO:H₂O ratio of 1:3 > CO:H₂O ratio of 1:2.5 > CO:H₂O ratio of 1:2. The CO conversion showed a high value of more than 97% at each CO:H₂O ratio. The water gas shift reaction at a CO:H₂O ratio of 1:3 showed the highest H2 increase rate and CO conversion.

• 한국항해항만학회지
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• 제46권6호
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• pp.547-553
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• 2022

본연구는 2019~2021년 14개 국적 외항 컨테이너 선사의 생산성 변화를 MPI(Malmquist Productivity Index)를 통해 분석하였다. 분석 기간 14개 선사의 MPI는 연평균 38.4% 증가한 것으로 분석되었다. MPI 변화 원인을 살펴보면, TCI(Technical Change Index)는 연평균 58.3% 증가하였으나 TECI(Technical Efficiency Change Index)는 연평균 12.6% 감소한 것으로 나타났다. 이는 선박의 효율성 또는 선대 규모 확대 효과보다는 운임상승에 의한 생산성 향상이 주원인임을 의미한다. 원양 해운선사인 HMM과 SM상선은 타 선사(아시아 역내 선사)와 달리 TECI와 TCI가 모두 생산성 향상에 긍정적인 영향을 미친 것으로 나타났다. 반면, 아시아 역내 선사의 경우 TCI(i.e. 운임상승) 값의 증가에 의한 생산성 향상이며, TECI값 중 SECI(Scale Effieicency Change Index) 값이 낮아 이들 선사는 선대 규모(규모의 경제) 변경에 따른 비용 절감 효과를 거의 누리지 못한 것으로 분석되었다.

• East Asian mathematical journal
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• 제27권4호
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• pp.417-432
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• 2011

This article deals with the teacher training for a minor in mathematics. We investigate the drawbacks of the teacher training which is enforced to resolve the overabundant teachers. And we claim that theachers must get a master's degree in a graduate school of education if they get a secondary teaching certificate.