• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2535-2541
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• 2009

Prebiotic isomaltooligosaccharide preparations contain $\alpha$-D-glucooligosaccharides comprising isomaltooligosaccharides (IMOs) and non-prebiotic maltooligosaccharides (MOs). They are both glucose oligosaccharides characterized by their degree of polymerization (DP) value (from 2 to $\sim$10), linkages types and positions (IMOs: $\alpha$-(1$\rightarrow$2, 3, 6 and in a lower proportion internal 1$\rightarrow$4) linkages, MOs: α-(1$\rightarrow$4) linkages). Their structure is the key factor for their prebiotic potential. In order to determine and elucidate the exact structure of unknown IMOs and MOs, unambiguous assignments of $^{13}C$ and $^1H$ chemical shifts of commercial standards, representative of IMOs and MOs diversity, have been determined using optimized standard one and two-dimensional experiments such as $^1H$ NMR, $^{13}C$ NMR, APT and ${^1}H-{^1}H$ COSY, TOCSY, NOESY and <$^1H-{^{13}}C$ heteronuclear HSQC, HSQC-TOCSY, and HMBC. Here we point out the differential effect of substitution by a glucose residue at different positions on chemical shifts of anomeric as well as ring carbons together with the effect of the reducing end configuration for low DP oligosaccharides and diasteroisotopic effect for H-6 protons. From this study, structural $^{13}C$ specific spectral features can be identified as tools for structural analysis of isomaltooligosaccharides.

• Clinical and Experimental Reproductive Medicine
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• 제21권3호
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• pp.227-232
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• 1994

In order to define the clinical characteristics of Korean women with polycystic ovary syndrome, clinical symptoms, biochemical features and ultrasonographic findings were determined in ninety PCO patients. Frequency of clinical manifestations were as follows:acne 42%, overweight 31 %, oily skin 14 %, hirsutism 10%. Relatively low frequencies of hirsutism is recognized in patients with Korean PCO syndrome. Mean(${\pm}$S.E.) of each hormone was:testosterone 1.18${\pm}$1.07ng/ml, LH 21.47${\pm}$${\pm}$2.6mIU/ml, FSH 7.26${\pm}$2.67mIU/ml, LH/FSH ratio 2.94${\pm}$1.29, prolactin 25.48${\pm}$46.33ng/ml, DHEA-S 333.78${\pm}$309.60ng/dl, 17-0HP 1.72${\pm}$1.74ng/ml. Mean 17-OHP after ACTH stimulation test was 5.07${\pm}$12.01ng/ml. Ultrasonographically measured mean ovarian volume were $11.02{\pm}5.92cm^3$ in right and $9.23{\pm}5.64cm^3$ in left and small sized multiple subcapsular follicular cysts were noted in 43 patients (47.9%) with PCO syndrome.

• 전력전자학회논문지
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• 제7권1호
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• pp.81-90
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• 2002

본 논문은 직접토크제어에 의한 리럭턴스 동기 전동기의 위치센서 없는 고성능 제어시스템을 제안한다. 이 시스템은 고정자 자속관측기, 속도/토크 관측기, 두 개의 디지털 히스테리시스 제어기, 최적 스위칭 룩업 테이블, IGBT 전압형 인버터, 그리고 TMS320C31 DSP보드로 구성된다. 넓은 속도 범위에서의 안정된 응답특성을 얻기 위해서 전동기 단자에서 얻어진 전압과 전류를 사용하는 폐루프 자속관측기를 사용하였다. 개발된 고성능 속도제어 시스템의 동특성을 검증하기 위해서 1.0[kW] 리럭턴스 동기 전동기를 사용하여 시뮬레이션과 실험을 수행한 결과 저속영역과 고속영역 모두 우수한 동특성을 얻을 수 있었다.

• 한국환경복원기술학회지
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• 제7권4호
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• pp.52-60
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• 2004

In order to analysis of the water pollution of the Anyang stream(one of the biggest branch streams of the Han River) and its main tributaries, the geological and topographical and rainfall features in its basin were investigated. To do this, the water samples were collected 23 points of the upper, mid and down of Anyang stream and its tributaries and were analyzed based on the chemical methods, Korean Biotic Index(KBI) and Saprobien systems. The Anyang stream basin has a characteristic of topographical torrential heavy rainfall like a typical rainfall feature in Korea. The concentration and the outflow rate of rainfall is very different in seasonal, and water pollution in dry season is especially severe. After 1997, although the water quality status of stream has been improved gradually, the concentration of T-N and SS at the upstream is increased due to the deficiency of facility used for collecting wastewater released from industrial factories, livestock farms and residential areas. The mainstream of the Anyang stream is classified into the 5th grade water as polysaprobic water area according to Saprobien system and the biotic index is over 2.5 in overall. Most of tributaries have 1~3 grade water limit with ${\alpha}$- and ${\beta}$-mesosaprobic except the upper and mid streams of Samsung tributary, in which pollution status is the lowest part. Though Sambong tributary is ${\alpha}$-mesosaproboic, biotic index is low because of the appearance of abundant benthos animals in farming and fishing villages.

• Journal of Power Electronics
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• 제3권4호
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• pp.249-258
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• 2003

This paper presents a high-efficient and cost effective three-phase AC/DC-DC/AC power conversion system with a single two-switch type active Auxiliary Resonant DC Link (ARDCL) snubber circuit, which can minimize the total power dissipation. The active ARDCL snubber circuit is proposed in this paper and its unique features are described. Its operation principle in steady-state is discussed for the three phase AC/DC-DC/AC converter, which is composed of PWM rectifier as power factor correction (PFC) converter, sinewave PWM inverter. In the presented power converter system not only three-phase AC/DC PWM rectifier but also three-phase DC/AC inverter can achieve the stable ZVS commutation for all the power semiconductor devices. It is proved that the proposed three-phase AC/DC-DC/AC converter system is more effective and acceptable than the previous from the cost viewpoint and high efficient consideration. In addition, the proposed two-switch type active auxiliary ARDCL snubber circuit can reduce the peak value of the resonant inductor injection current in order to maximize total system actual efficiency by using the improved DSP based control scheme. Moreover the proposed active auxiliary two-switch ARDCL snubber circuit has the merit so that there is no need to use any sensing devices to detect the voltage and current in the ARDCL sunbber circuit for realizing soft-switching operation. This three-phase AC/DC-DC/AC converter system developed for UPS can achieve the 1.8% higher efficiency and 20dB lower conduction noise than those of the conventional three-phase hard-switching PWM AC/DC-DC/AC converter system. It is proved that actual efficiency of the proposed three-phase AC/DC-DC/AC converter system operating under a condition of soft switching is 88.7% under 10kw output power.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제15권9호
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• pp.617-625
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• 2009

NAND 플래시 메모리는 부피가 작고, 가볍고, 소비전력이 낮으며 입출력이 빠르고 집적도가 높아 최근 임베디드 기기들에 널리 사용되고 있다. 그러나 NAND 플래시 메모리는 지움 연산을 수반하는 가비지 컬렉션 연산을 수행해야 한다. 게다가 지움 연산은 속도가 느리고, 각 블록마다 지움 연산 횟수가 제한이 있다. 따라서 제안하는 가비지 컬렉션 기법은 전체 지움 연산 횟수와 각 블록의 지움 횟수 편차를 감소시키고, 가비지 컬렉션 수행 시간을 최소화하는데 초점을 맞춘다. NAND 플래시 메모리는 유효 페이지, 무효 페이지, 빈 페이지로 구성되어 있다. 제안하는 기법은 페이지들의 비율을 이용해 가비지 컬렉션의 수행 시기를 결정하고 대상 블록을 선택한다. 그리고 할당 기법과 그룹 관리기법을 추가적으로 구현하였다. 실험 결과 제안한 정책은 기존의 Greedy나 CAT 기법에 비해 전체 지움 횟수를 최소화 하면서, 최대 82% 지움 횟수 편차를 감소시켰고, 최대 75%의 가비지 컬렉션 수행 시간을 단축시켰다.

• 대한원격탐사학회지
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• 제23권4호
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• pp.273-285
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• 2007

대부분의 스테레오 정합 방법은 두 점간의 대응점을 측정하는데 있어 밝기값을 사용하며 잡음의 영향을 받은 화소가 정합에 사용될 경우 정합 성능이 저하된다. 따라서 잡음은 정합 성능을 결정짓는 중요한 역할을 한다. 본 논문에서는 고해상도 위성영상에서 정합 성능을 향상시키기 위해 잡음에 강건한 밝기 필터와 에지 필터를 이용하여 정합하는 방법을 제안한다. Mean, Median, Midpoint, Gaussian 필터와 같은 밝기 필터와 Gradient, Roberts, Prewitt, Sobel, Laplacian 필터와 같은 에지 필터를 사용하였다. 에지필터와 밝기 필터의 성능 평가를 위해 균일 잡음 또는 가우시안 잡음이 첨가된 합성 영상과 위성 영상에 대해 실험을 수행하였고 필터들은 성능에 따라 순위를 정하였다. 밝기 필터와 에지 필터들 중에서 Median 필터와 Sobel 필터가 가장 우수한 성능을 나타낸 반면에 Midpoint 필터와 Laplacian 필터는 가장 저조한 성능을 나타내었다. Ikonos 스테레오 위성영상을 실험 영상으로 사용하였으며 Median 필터와 Sobel 필터를 이용한 정합 방법이 다른 필터 조합을 이용한 정합 방법보다 향상된 정합 결과를 나타내었다.

• 산업경영시스템학회지
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• 제41권4호
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• pp.146-159
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• 2018

This study analyzed what premium features significantly affect customer satisfaction and their recommendation, and what factors significantly affect product attributes. In the process, first, the loyalty program and the customer compensation program were studied to determine the impact of the customer satisfaction and recommendation. The study analyzed that quality and design of product properties had significant effects on all factors, but the brand was not significantly affected. Second, while superiority, differentiation and scarcity of luxury items are significant to customer satisfaction but superiority is only significant in relation to recommendation intention. Third, the preceding study shows that the customer compensation program has a significant impact on sales growth, but the study found that it was not for imported luxury car customers. Fourth, if the royalties program is low in awareness, it has been analyzed that the scarcity and customer satisfaction relationships among luxury goods have been adjusted. On the contrary, if there is a high level of awareness, it is analyzed that there is a control effect customer satisfaction and differentiation among luxury brands. In the conclusion, in order to satisfy customers at the import luxury car market, the differentiation of luxury goods by standard index must be strengthened and the brand must be strengthened among the attributes of the product. In addition, by raising awareness of the royalties program, the relationship between differentiation and customer satisfaction can be enhanced.

• 대한금속재료학회지
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• 제49권1호
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• pp.25-31
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• 2011

Solid oxide fuel cells (SOFCs) have many attractive features for widespread applications in generation systems. Recently, stainless steels have attractive materials for metallic bipolar plate because metallic bipolar plates have many benefits compared to others such as graphite and composite bipolar plates. SOFC operates on high temperature of about $800{\sim}1000^{\circ}C$ than other fuel cell systems. Thus, many studies have attempted to reduced the operation temperature of SOFC to about $600{\sim}800^{\circ}C$, which is the intermediate temperature (IT) of SOFC. Low cost and high-temperature corrosion resistance are very important for the practical applications of SOFC in various industries. In this study, two specimens, 304 and 430 stainless steels with and without different pre-surface treatments on the surface were investigated. And, specimens were exposed at high temperature in the box furnace under oxidation atmosphere of $800^{\circ}C$. Oxidation behavior have been investigated with the materials exposed at different times (100 hrs and 400 hrs) by SEM, EDS and XRD. By increasing exposure time, the amount of metal oxide increased in the order like; STS304 < STS430 and As-received < As-polished < Sand-blast specimens.

• 한국정보통신학회논문지
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• 제24권8호
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• pp.970-977
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• 2020

협업 필터링 추천 기법은 전자상거래 기업들이 추천시스템을 도입한 이래로 가장 널리 사용되고 있다. 그러나 온라인에서 상품이나 콘텐츠의 구매가 일상화되면서 단순히 구매 고객의 평점만을 사용하는 추천 방식으로는 추천의 정확성이 낮아지는 문제점이 발생하였다. 본 논문에서는 추천의 정확성을 향상시키기 위해, 상품 리뷰를 분석하고 이를 가중치로 사용한 협업 필터링 추천 기법을 제안한다. 제안하는 기법은 상품에 대한 리뷰를 텍스트 마이닝 기법으로 정제하여 특징을 추출하고 감성 기반 분석을 통해 감성 점수를 산출한다. 사용자에게 더 나은 아이템을 추천하기 위해 산출된 점수를 아이템 예측 값 계산 시 가중치로 사용한다. 실험을 통해 전통적인 협업 필터링 기법보다 제안하는 기법의 정확성이 향상되는 것을 확인할 수 있었다.