컴퓨터 탐색을 이용한 재고관리 시스템의 최적화

윤승철 한국경영과학회 1996 한국경영과학회 학술대회논문집 Vol.- No.1

The main objective of this research is to develop the optimal control method for a Distribution Center - multi Branch inventory distribution system. With the continuous review policy, the distribution center places an order for specific order quantity is replenished after a certain lead time. Also, each branch places an order for particular order quantity to the distribution center to satisfy the customer demands, and receives the replenishment after a lead time. When an out of stock condition occurs during an order cycle, a backorder is placed to the upper level to fill the unfilled demands. With these situation, variable demand and variable lead time are used for better industrial practice. Further, actual lead times with a generic lead time distribution are used in developing the control model. Under the actual lead time model, the customer service measures actually attained for the distribution center and each branch are explained as the effective customer service measures. Thus, throughout the optimal control (using computer search procedures), we can set the desired service levels for the distribution center and each branch to produce the effective service level for each branch which is consistent with the goal level of service for each branch. At the same time, the entire distribution system keeps minimum inventories.

펌프-탐지 기법에 쓸 광섬유 레이저의 펄스 반복률 안정화

윤승철,김현우,김명훈,김진승 한국물리학회 2013 새물리 Vol.63 No.11

We demonstrate a harmonically mode-locked erbium-doped fiber ring laser by using both single-walled carbon nanotubes as saturable absorber and a regenerative phase modulation that produces laser pulses with a repetition rate of 140 MHz. From the detected beat spectrum of the laser output, a sinusoidal clock signal of 140 MHz, the 15th harmonic of the fundamental mode-locking frequency, was extracted to drive the phase modulator. We obtain a soliton pulse train synchronized with the modulation signal, whose repetition rate are locked to the external reference frequency through a phase-locked loop. The generated soliton pulses have a center wavelength of 1563.5 nm, a linewidth of 4.2 nm, and a pulse width of about 610 fs, as estimated from the time-bandwidth product of 0.315 for the bandwidth-limited sech$^2$ pulses. 재생형 위상 변조에 의한 고차 조화 모드잠금 방식으로 펄스 반복률이 140 MHz인 광섬유 레이저를 만들었다. 레이저 펄스 출력의 종모드 간 맥놀이 스펙트럼으로터 모드잠금 기본 주파수의 15차 고조파인 140 MH의 성분을 추출하고 공진기 내 위상 변조기를 구동하여, 등간격으로 정렬된 펄스열을 얻었다. 외부 환경 변화에 의한 펄스 반복률의 변화를 외부 기준 주파수에 고정시켜 펄스 반복률을 안정시켰다. 이 레이저의 중심 파장은 1563.5 nm이고 반값 선폭은 4.2 nm이며, 솔리톤 펄스의 변환 한계를 고려하면 펄스폭 추정값은 610 fs이다.

주파수 변환 귀환 방식의 광섬유 솔리톤 레이저에서 Self Heterodyne에 의한 펄스폭 측정

윤승철 한국광학회 1999 한국광학회지 Vol.10 No.1

주파수 변환 귀환 방식의 광섬유 솔리톤 레이저에서 고진기 내의 광주파수 변화기를 이용하여 self-heterodyne 방식으로 펄스폭을 측정하엿다. 공진기 네에서 주파수 변환기를 통과하기 전과 후의 펄스열과 헤테로다인 시키고 두 펄스열 간의 지연길이를 가변 시키면서 맥놀이 주파수 성분의 세기를 측정함으로써 진폭 자기상관 함수를 얻었으며 이로부터 펄스폭을 측정할 수 있었다. 그 결과, 기존의 제2차 고조파 발생을 이용한 자기상관 방식과 r의 같은 결과를 얻었다. We demonstrate a new pulse characterization scheme relying on self-heterodyning that uses intracavity frequency shifter in a fiber soliton laser with frequency shifted feedback. By heterodyning the frequency-shifted pulse stream with the unshifted one, and by measuring the beat strength with varying the delay length between two pulse streams, we obtain the amplitude autocorrelation function from which we estimate the pulsewidth. The result is in good agreement with that obtained by the autocorrelation relying on the second harmonic generation.

재생형 위상 변조에 의한 '8'자 구조 광섬유 솔리톤 레이저의 고차 조화 모드록킹

윤승철,박희갑 한국광학회 1999 한국광학회지 Vol.10 No.2

고반복률의 안정된 솔리톤 펄스열 출력을 얻기 위해 재생형 위상 변조에 의한 고차 조화 모드록킹 방식을‘8’구조 광섬유 레이저에 적용하고 실험하였다. 레이저 펄스 출력의 종모드간 맥놀이 스펙트럼으로부터 모드록킹 기본 주파수의 96차 고조파인 400 MHz 성분을 추출하고. 이를 증폭하여 공진기 내의 위상 변조기를 구동함으로써 변조기의 변조 신호에 따라 등간격으로 정렬된 솔리톤 펄스열 출력을 얻을 수 있었다. 이때 솔리톤 펄스의 반치폭 930 fs, 반치 파장선폭은 3.1 nm 였으며, 펄스폭과 주파수 대역폭의 곱이 0.359로써 변환한계에 가까운 솔리톤 펄스임을 알 수 있었다. 변조 주파수가 레이저의 종모드간 주파수 차이와 언제나 정확히 일치하므로 능동형 모드록킹에서 흔히 요구되는 공진기 길이의 조절없이도 안정적인 고차 조화 모드록킹이 가능하였다. We demonstrated a harmonic mode locking scheme that used regeneratie phase modulation to get a high and stable repetition rate in a figure-of-eight fiber soliton laser. From the detected beat spectra of the laser output, a sinusoidal clock freguency tone of 400 MHz, the 96th harmonics of the fundamental mode locking frequency, was extracted with a high Q filter and was used to drive the phase modulator, resulting in stable output of soliton pulse train synchronized with the modulation signal. Generated soliton pulses had FWHM pulsewidth of 930 fs and 3.1 nm linewidth, yielding pulsewidth-bandwidth product of 0.359 that was close to the transform limit. As the modulation frequency always followed the beat frequency of laser modes, stable harmonic mode locking was achieved without the adjustment of the cavity length, which has been commonly required in actively mode-locked lasers.

N-지점 재고유통시스템의 비상공급과 재고조정 : N Branch Inventory Distribution System

윤승철 단국대학교 산업연구소 1995 산업연구 Vol.18 No.-

在庫分配 시스템의 最適化 方法

尹承哲 단국대학교 산업연구소 1996 산업연구 Vol.19 No.-

유통시스템의 재고분석 : 서비스측정 모델 Model for Service Measures

尹承哲 단국대학교 산업연구소 1994 산업연구 Vol.17 No.-

Analysis of Investment in Nanotechnology Using DEA

윤승철,김흥규 한국산업경영시스템학회 2018 한국산업경영시스템학회지 Vol.41 No.4

This study aims to objectively measure the efficiency of nanotechnology R&D programs by systematically evaluating the inputs and outputs of nanotechnology R&D activities and to find implications for improving the efficiency of nanotechnology R&D programs. Data on input factors such as R&D investment, R&D manpower, R&D period, and output factors such as paper, patent, and commercialization for R&D projects which started from 2008 or afterwards and ended by 2011 are gathered through National Science and Technology Knowledge Information Service, which are used for efficiency evaluation. In this study, we analyzed R&D efficiency in detailed technology units in depth. The process taken in this study is as follows. First, the basic statistics of input and output factors to compare and analyze R&D investment, R&D manpower, R&D period, paper, patent, and commercialization status by technology unit are analyzed. Next, DEA models are utilized to derive the overall efficiency, pure technology efficiency, and scale efficiency by conducting the efficiency evaluation for each technology unit, from which implications for strategic budget allocation are derived. In addition, partial efficiency evaluation is conducted to identify advantages and disadvantages of each technology unit. In turn, cluster analysis is performed to identify similar technology units, from which implications for efficiency improvement are derived.

VR 쇼핑의 시나리오기법과 베스확산모형을 이용한 수요예측

윤승철,김흥규 한국무역연구원 2018 무역연구 Vol.14 No.6

VR is a technology that makes virtual space using computer technology and which is currently used mainly in the entertainment field such as games. However, its application is getting wider in scope as new contents are created by combining it with other industrial fields of study. Therefore, it is interesting to find out what effect VR shopping will have on the future of the distribution industry. Global distributors are testing the introduction of a new distribution model using VRs because VR shopping may become popular in the future, as people who actually shopped in real markets have moved to online shopping via PCs and then to mobile shopping. In this study, we estimated the size of the domestic VR shopping market. Since the VR industry is still in its introduction stage, there are almost no quantitative data, which are useful for predicting how the VR customer base will evolve. We therefore estimate the parameters of the Bass Diffusion Model using data on recent similar products that meet each of several scenarios. We then estimated the VR market size.

공간 선택적 브릴루앙 산란을 이용한 분포형 광섬유 센서의 시뮬레이션

윤승철,서민성,박희갑,Yun, Seung-Chul,Seo, Min-Sung,Park, Hee-Gap 한국광학회 2006 한국광학회지 Vol.17 No.2

광주파수 변조된 펌프와 프로브 빛의 광섬유 내 중첩을 시간 영역에서 직접 다루는 방법으로 공간 선택적 브릴루앙 산란 방식의 분포형 광섬유 센서를 시뮬레이션 하였다. 광섬유 내 브릴루앙 이득 분포의 시간/공간적 변화를 구하였고, 이종 광섬유의 접속과 온도 분포가 존재하는 경우에 대해 시뮬레이션 하여 분포형 센서로서 합당한 결과를 얻었다. 변조 파형으로서 정현파 대신에 삼각파를 이용한 경우에 정현파에 비해 공간 분해능 면에서 유리한 것으로 나타났다. We implement numerical simulations for the distributed optical fiber sensor system that uses the spatially-selective Brillouin scattering, by treating the superposition of the optical-frequency-modulated pump/probe waves in the time domain. We obtain temporal and spatial distributions of Brillouin gain for various cases. Simulations are applied to the case of concatenated optical fibers of different kinds and the case of distributed temperature along the fiber, which give reasonable results for the distributed sensor. The result of using a triangular wave instead of a sinusoidal one as a modulation waveform shows that the triangular wave modulation has an advantage in spatial resolution.