• Bulletin of the Korean Chemical Society
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• 제7권3호
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• pp.224-228
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• 1986

A nonlinear theory is presented for the fluctuations of intermediates in the Brusselator near the critical point caused by diffusion. The method used is the two time scaling method different from the conventional method in the sense that a slight nonlinear effect is included in the initial time region where the linear approximation is conventionally valid. The result obtained by the nonlinear theory shows that fluctuations close to the critical point approach the value of a stable steady state or deviate infinitely from an unstable steady state, as time goes to infinity, while the linear theory gives approximately time-independent fluctuations. A brief discussion is given for the correlation at a time between fluctuating intermediates when the system approaches a stable steady state.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제26권4호
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• pp.263-279
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• 2022

This paper presents an automatic inspection of defects in semiconductor images. We devise a statistical method to find defects on homogeneous background from the observation that it has a log-normal distribution. If computer aided design (CAD) data is available, we use it to construct a signed distance function (SDF) and change the pixel values so that the average of pixel values along the level curve of the SDF is zero, so that the image has a homogeneous background. In the absence of CAD data, we devise a hybrid method consisting of a model-based algorithm and two neural networks. The model-based algorithm uses the first right singular vector to determine whether the image has a linear or complex structure. For an image with a linear structure, we remove the structure using the rank 1 approximation so that it has a homogeneous background. An image with a complex structure is inspected by two neural networks. We provide results of numerical experiments for the proposed methods.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.348-353
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• 1994

Magnetic Servo Levitation (MSL) has been proposed as a method to drive a fast-tool servo system. This paper discusses some fundamental control and modeling issues in the development of a long-range high-bandwidth fast-tool servo based on MSL. A resursive linear model is developed to describe the system's dynamics linear model is developed to describe the system's dynamics, and further used to discuss controller design. For a given controller architecture, the performance of two controllers is then compared, one based on an approximation to the inverse plant dynamics, the second based on a adaptive neural network.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.403-411
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• 2013

Horizontal construction projects such as oil and gas pipeline projects typically involve repetitive-work activities with the same crew and equipment from one end of the project to the other. Repetitive scheduling also known as linear scheduling is known to have superior schedule management capabilities specifically for such horizontal construction projects. This study discusses on expanding the capabilities of repetitive scheduling to account for the variance in production rates and visual representation by developing an automated alignment based linear scheduling program for applying temporal and spatial changes in production rates. The study outlines a framework to apply changes in productions rates when and where they will occur along the horizontal alignment of the project and illustrates the complexity of construction through the time-location chart through a new linear scheduling model, Linear Scheduling Model with Varying Production Rates (LSM_VPR). The program uses empirically derived production rate equations with appropriate variables as an input at the appropriate time and location based on actual 750 mile natural gas liquids pipeline project starting in Wyoming and terminating in the center of Kansas. The study showed that the changes in production rates due to time and location resulted in a close approximation of the actual progress of work as compared to the planned progress and can be modeled for use in predicting future linear construction projects. LSM_VPR allows the scheduler to develop schedule durations based on minimal project information. The model also allows the scheduler to analyze the impact of various routes or start dates for construction and the corresponding impact on the schedule. In addition, the graphical format lets the construction team to visualize the obstacles in the project when and where they occur due to a new feature called the Activity Performance Index (API). This index is used to shade the linear scheduling chart by time and location with the variation in color indicating the variance in predicted production rate from the desired production rate.

• 공업화학
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• 제10권1호
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• pp.166-172
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• 1999

폐수중 중금속 이온을 제거하기 위한 방법으로 키토산 비드에 의한 금속 이온의 고정층 흡착 특성을 조사하였다. 게껍질로부터 키틴을 추출하고 이를 탈아세틸화 반응시켜 키토산을 제조하였다. 키토산은 비드로 만들어 중금속 흡착제로 사용하였다. 키토산 비드에 대한 $Cu^{2+}$, $Co^{2+}$, $Ni^{2+}$ 이온의 단성분 평형 흡착 실험 결과로부터 Freundlich와 Langmuir 흡착등온식을 결정하였다. 흡착등온식에 의하면 키토산 비드에 대한 중금속 이온의 흡착 세기는 $Cu^{2+}$>$Co^{2+}$>$Ni^{2+}$의 순서로 나타났다. 키토산 비드에 대한 중금속 이온의 단성분 또는 다성분계 고정층 흡착 실험으로부터 흡착 파과곡선을 구하였다. 단성분 흡착등온식으로 다성분 흡착 평형을 예측할 수 있는 IAS (ideal adsorbed solution) 이론을 적용하여 LDFA (linear driving force approximation)에 의한 고정층 흡착 모델식을 수치해 기법으로 모사하여 실험결과와 비교하였다. LDFA에 의한 모델식을 적용한 결과 키토산 비드에 대한 중금속 이온의 단성분 및 다성분계 고정층 흡착거동을 잘 모사할 수 있었다.

• 대한기계학회논문집A
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• 제20권5호
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• pp.1543-1551
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• 1996

The static tensile load bearing capability of as adhesively-bonded tubular single lap jint that is calculated usign the linear mechanical properties of adhesive is usually far from the experimentally determined because the majority of the load transfer of the adhesively-bonded jointd is accomplished by the nonlinear behavior of the rubber-toughened eoxy adhesive. In this paper, both the nonlinear mechanical properties and the fabrication residual thermal stresses of adhesive were included in the calculation of the stresses of adhesively-bonded joints. The onlinear tensile properties of adhesive were approximated by an exponential form which was represented by the initial tensile modulus and ultimate tensile stength of adhesive. The stress distribution in the adhesive were calculated by applying the load obtained from the tensile tests. From the tensile tests and the stress analysis of adhesively-bonded hoints, the failure model for adhesively-bonded tubular single lap joints was proposed.

• 전자공학회논문지
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• 제52권9호
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• pp.36-44
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• 2015

본 논문에서는 광각 카메라에서 발생하는 비네팅 왜곡과 배럴 왜곡을 효율적으로 보정하기 위한 낮은 복잡도의 프로세서를 제안하고, 이를 구현한 결과를 보인다. 제안하는 프로세서에서는 비네팅 왜곡과 배럴 왜곡 보정 시 복잡한 연산을 수반하는 고차 다항식과 같은 피팅 함수를 구간 선형 근사하여 보정 품질을 유지하면서도 연산 복잡도를 크게 낮추었다. 이를 기반으로, 배럴 왜곡과 비네팅 왜곡을 중첩적으로 보정하도록 설계하여 전체적인 하드웨어 복잡도를 낮추었다. 제안하는 프로세서는 $0.11{\mu}m$ CMOS 공정을 사용하여 18.6K의 논리 게이트로 구현되었으며, $2048{\times}2048$ 크기의 영상에 대하여 최대 200Mpixels/s의 속도로 보정이 가능하다.

• Archives of Plastic Surgery
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• 제38권2호
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• pp.143-147
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• 2011

Purpose: A Tessier classification number 7 cleft is an uncommon malformation that results from a failure of mesenchymal fusion within the maxillary and mandibular prominences of the 1st pharyngeal arch. Many operative techniques of the number 7 cleft repair have been proposed to restore function and improve aesthetics. Fifteen patients underwent repair of a number 7 cleft over 13 years by a modification of the surgical Technique, and an appraisal of the operative outcome is reported herein. Methods: A retrospective review was conducted involving 15 patients with number 7 clefts who underwent surgery from 1996 to 2009. The changes in surgical technique included skin closure, attachment of the orbicularis oris muscle, and position of the repaired commissure; the changes were analysed with a review of the medical records and the outcomes of surgery were analysed via photographs. Specifically, the technique of skin closure was changed from the a Z-plasty to a linear closure, the orbicularis oris muscle overlapped attachment was replaced by a side-to-side approximation with horizontal mattress sutures, and the position of the repaired commissure was changed from 1 mm laterally to 1 mm medially in reference to the non-cleft side. Results: A Z-plasty caused additional cutaneous scarring, an overlapped attachment of the orbicularis oris muscle caused a thick oral commissure, and the repaired commissure migrated to the lateral side, so a 1 mm, laterally-positioned commissure caused asymmetry. The altered procedure included a linear skin closure, a side-to-side orbicularis oris muscle approximation, and a 1 mm, medially-positioned commissure, which together resulted in a good outcome. Conclusion: The altered procedure for repair of a number 7 cleft as described herein, yields a short scar, no functional problems with the orbicularis oris muscle, a thin oral commissure, and symmetry of the repaired commissure.

• 공업화학
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• 제10권2호
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• pp.268-274
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• 1999

평균분자량이 $8.2{\times}10^5$, 탈아세틸화도가 85%인 키토산을 2 wt % 초산 수용액에 용해시킨 후 졸-겔법에 의해 키토산 비드를 제조하였다. 졸-겔법에 의해 제조된 키토산 비드는 SEM 사진과, BET 측정으로 다공성임을 확인할 수 있었다. 다공성 키토산 비드에 의한 $Cu^{2+}$의 흡착평형은 Sips식으로 잘 묘사할 수 있었으며, 키토산 비드 내부에서의 확산과정은 세공 및 표면확산 기구로 설명할 수 있었다. 고정층에서 $Cu^{2+}$의 흡착거동은 linear driving force approximation (LDFA)으로 잘 묘사할 수 있었으며, 본 연구에 사용된 다공성 키토산 비드는 $Cu^{2+}$을 회수하는데 우수한 흡착제임을 확인할 수 있었다.

• 전기전자학회논문지
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• 제5권1호
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• pp.1-7
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• 2001

본 논문에서 역 방향 링크 채널에 대해 비 선형 등화기를 이용하여 CDMA 셀룰라 시스템을 연구하였다. 일반적으로 무선 통신에서 불확실한 채널 특성 때문에 Observable 들의 확률분포는 유한 세트의 파라미터로 규정될 수 없다. 대신에 training 샘플에 기반을 둔 Quantile과 Vector Quantizer를 사용함으로서 유한 수의 disjoint된 영역으로 m차 샘플 공간으로 분할하였다. 제안된 알고리듬은 RMSA 알고리즘에 의해 예측된 Quantile와 조건부 분할 모멘트에 따른 regression function의 부분적인 근사에 근간을 두고 있다. 본 논문의 등화기와 검출기는 잡음 분포의 Variation에 민감하지 않다는 관점에서 상당히 강한 특성을 보여 준다. 주요 아이디어는 Robust equalizer와 Robust partition detector가 어떤 환경의 무선 채널 하에서도 partition되지 않은 Observation space의 일반적인 등화기 보다 Observation의 등 확률로 분할된 부 공간에서 더 낳은 성능을 보여 준다. 또한 이런 개념을 CDMA 시스템에 적용하여 BER 성능을 분석하였다.