• Journal of Mechanical Science and Technology
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• 제15권9호
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• pp.1257-1267
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• 2001

For efficient mechanical system optimization, a new two-point approximation method is presented. Unlike the conventional two-point approximation methods such as TPEA, TANA, TANA-1, TANA-2 and TANA-3, this introduces the shifting level into each exponential intervening variable to avoid the lack of definition of the conventional exponential intervening variables due to zero-or negative-valued design variables. Then a new quadratic approximation whose Hessian matrix has only diagonal elements of different values is proposed in terms of these shifted exponential intervening variables. These diagonal elements are determined in a closed form that corrects the typical error in the approximate gradient of the TANA series due to the lack of definition of exponential type intervening variables and their incomplete second-order terms. Also, a correction coefficient is multiplied to the pre-determined quadratic term to match the value of approximate function with that of the previous point. Finally, in order to show the numerical performance of the proposed method, a sequential approximate optimizer is developed and applied to solve six typical design problems. These optimization results are compared with those of TANA-3. These comparisons show that the proposed method gives more efficient and reliable results than TANA-3.

• 대한기계학회논문집A
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• 제25권9호
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• pp.1423-1431
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• 2001

Based on the exponential intervening variable, a new two-point approximation method is presented. This introduces the shifting level into each exponential intervening variable to avoid the lack of def inition of the conventional exponential intervening variables due to zero-or negative-valued design variables. Then a new quadratic approximation whose Hessian matrix has only diagonal elements of different values is proposed in terms of these intervening variables. These diagonal elements are determined in a closed form that corrects the typical error in the approximate gradient of the TANA series due to the lack of definition of exponential type intervening variables and their incomplete second-order terms. Also, a correction coefficient is multiplied to the pre-determined quadratic term to match the value of approximate function with that of the previous point. Finally, in order to show the numerical performance of the proposed method, a sequential approximate optimizer is developed and applied to solve six typical design problems. These optimization results are compared with those of TANA-3. These comparisons show that the proposed method gives more efficient and reliable results than TANA-3.

• 한국컴퓨터정보학회논문지
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• 제11권5호
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• pp.59-67
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• 2006

본 논문에서는 지수평활을 이용한 법원경매 정보 시스템의 낙찰가 예측 방법을 제안하였다. 이 시스템은 권리분석을 위하여 낙찰가를 예측하고, 낙찰예측가에 따라 배당 정보를 제공하도록 설계되어 있으며 이를 구현하기 위하여 물건 자료의 입력 인터페이스와 정보 제공을 위한 웹 인터페이스를 구축하였다. 자료 입력 인터페이스는 자료의 입력, 수정, 삭제 기능을 가지며, 웹 인터페이스는 법원경매 물건을 중심으로 관련 정보를 제공한다. 실시간 정보 제공에 초점을 두고 자동 권리분석이 가능하도록 하기 위하여 낙찰가를 시계열 자료로 표현하여 지수평활을 이용한 낙찰예상가를 예측하는 방법을 제안하고, 기존의 방법과 비교 실험을 통하여 제안방법의 유효성을 검증한다.

• 한국수산과학회지
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• 제40권4호
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• pp.201-209
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• 2007

Line transect sampling in a sighting survey is one of most widely used methods for assessing animal abundance. This study applied distance data, collected from three sighting surveys using line transects for finless porpoise that were conducted in 2004 and 2005 off the west coast of Korea, to four models (hazard-rate, uniform, half-normal and exponential) that can use a variety of detection functions, g (x). The hazard-rate model, a derived model for the detection function, should have a shoulder condition chosen using the AIC (Akaike Information Criterion), as the most suitable model. However, it did not describe a shoulder shape for the value of g(x) near the track tine and underestimated g (x), just as the exponential model did. The hazard-rate model showed a bias toward overestimating the densities of finless porpoises with a higher coefficient of variation (CV) than the other models did. The uniform model underestimated the densities of finless porpoise but had the lowest CV. The half-normal model described a detection function with a shape similar to that of the uniform model. The half-normal model was robust for finless porpoise data and should be able to avoid density underestimation. The estimated abundance of finless porpoise was 3,602 individuals (95% CI=1,251-10,371) inshore in 2005 and 33,045 individuals (95% CI=24,274-44,985) offshore in 2004.

• 한국통신학회논문지
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• 제31권12A호
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• pp.1229-1237
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• 2006

DCF에서는 백오프 스테이지(backoff stage), 백오프 카운터(backoff counter), 경쟁 윈도우(contention window)의 세 가지 매개변수를 사용하여 충돌이 발생하면 백오프 스테이지를 하나씩 증가시키고 백오프 카운터를 선택하는 범위인 경쟁 윈도우를 두 배씩 증가시키는 이진 지수적인 백오프(BEB : Binary Exponential Backoff) 방식을 사용하여 전송 프레임간의 충돌 발생 가능성을 줄이고 있다. 그러나 무선 자원을 공유하는 단말의 수가 증가 할수록 충돌 발생 가능성이 증가하여 비효율적으로 자원을 사용하는 문제점이 있다. 따라서 본 논문에서는 무선 자원을 효율적으로 사용하고 무선 랜의 성능을 향상시키기 위해 충돌발생 시 경쟁 윈도우를 최대로 유지하고 전송 성공 시 경쟁 윈도우를 반으로 줄이는 이진 음지수적인 백오프(BNEB : Binary Negative-Exponential Backoff) 방식을 제안하고 IEEE 802.11, 802.11a, 802.11b의 세 가지 표준에 대해서 포화상태 및 정상 트래픽 상태에서의 성능 평가를 수행하였다.

• 대한수학회지
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• 제38권6호
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• pp.1107-1116
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• 2001

In this paper, we study the rationality of the Reidemeister zeta function of an endomorphism of a group extension. As an application, we give sufficient conditions for the rationality of the Reidemeister and the Nielsen zeta functions of selfmaps on an exponential solvmanifold or an infra-nilmanifold or the coset space of a compact connected Lie group by a finite subgroup.

• Journal of the Korean Data and Information Science Society
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• 제26권6호
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• pp.1225-1238
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• 2015

본 연구에서는 직장암 환자들의 수술 후 재발까지의 시간 데이터에 대해 집단 간 생존함수 양상에 차이가 있는지 로그 순위 검정 결과 유의수준 10%에서 포도당 단일수송체 (GLUT1)의 수준, 수술 전 병기 (cstage), 수술 후 병기 (ypstage)에 따른 차이가 유의하며, Cox 비례위험률 모형을 이용하여 검정한 결과 가장 유의한 공변량은 포도당 단일수송체와 수술 후 병기였다. 지수분포를 따른다고 가정할 경우, 우도함수를 기반한 여러 가지 위험률 변화점을 추정하였다.

• 산업경영시스템학회지
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• 제38권2호
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• pp.40-46
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• 2015

The modular assembly system can make it possible for the variety of products to be assembled in a short lead time. In this system, necessary components are assembled to optional components tailor to customers' orders. Budget for inventory investments composed of inventory and purchasing costs are practically limited and the purchasing cost is often paid when an order is arrived. Service cost is assumed to be proportional to service level and it is included in budget constraint. We develop a heuristic procedure to find a good solution for a continuous review inventory system of the modular assembly system with a budget constraint. A regression analysis using a quadratic function based on the exponential function is applied to the cumulative density function of a normal distribution. With the regression result, an efficient heuristics is proposed by using an approximation for some complex functions that are composed of exponential functions only. A simple problem is introduced to illustrate the proposed heuristics.

• 터널과지하공간
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• 제11권1호
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• pp.20-29
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• 2001

터널 굴착으로 인한 천반의 최종 변위는 내공변위 곡선을 시간과 거리에 따른 임의의 함수로 표현하여 예측할수 있다. 본 연구에서는 도심지 주변의 천층 광폭터널에서의 변위 예측식의 적합성을 검토하였다. 연구 대상 터널은 도심과 무등산 공원의 경계에 위치하여 터널 상부의 토피고가 낮고 폭이 넓은 터널이다. 연구 결과, 토피고가 낮은 갱구부에서 풍화암 지반이 강관다단 그라우팅 및 forepoling 보강에 의해 탄소성지반이 아닌 탄성지반에 준하는 특성을 나타내는 풍화암 내지 연암층으로 된 연구대상 터널의 경우 지수함수식이 더 적합한 것으로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제13권6호
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• pp.892-896
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• 2003

High-level expression of the lipase B26 gene from Bacillus pumilus was achieved using Bacillus subtilis Chungkookjang isolated from the Korean traditional fermented bean paste, Chungkookjang. For the secretory production of recombinant lipase B26 in a Bacillus host system, pLipB26 was constructed by ligating the lipase B26 gene into the recently designed Escherichia coli-Bacillus shuttle vector, pLipSM, and that was then transformed into B. subtilis Chungkookjang. Among the various vector, medium, and host combinations, B. subtilis Chungkookjang harboring the pLipB26 exhibited the highest lipase activity in PY medium, and B. subtilis Chungkookjang secreted two times more enzymes than B. subtilis DB 104 under the same condition. When B. subtilis Chungkookjang harboring the pLipB26 was cultured in a 5-1 jar-fermentor containing 21 of a PY medium, the maximum lipase activity (140 U/ml) and production yield (0.68 g/l) were obtained during the late exponential phase from a cell-free culture broth. Although B. subtilis Chungkookjang also secreted extracellular proteases at the late exponential phase, these results suggested the potential of B. subtilis Chungkookjang as a host for the secretory production of foreign proteins.