• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.64-70
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• 1999

A new multi-beam optical system is presented on the grounds of tri-positioning systems in this paper. The system has been developed to improve the data transfer rate for the optical disk system. The actuating system is composed of a tracking and focusing actuating system basically and a newly developed beam rotating actuator. The beam rotating actuator is employed in a multi-beam optical system to trace more than one track simultaneously. The multi-beam optics is established through the optical simulation and several experimental trials. The differential phase tracking method is used in the tracking error signal detection based on the only one beam spot. We also analyze the characteristics of multi-beam optical system. The experimental result shows that the multi-beam positioning system has performance adequate to the multi-beam optical disk system.

• 한국안전학회지
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• 제32권4호
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• pp.114-121
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• 2017

In order to overcome the limitations of the mobile speed system for 1 lane, this study is used a multi-laser beam to develop a mobile speed measuring system, using a multi-phase beam. By using multi-laser beam, least squares algorithms and speed error processing algorithms were developed to improve speed accordancy and speed error rates compared to conventional mobile speed meters using a single laser beam. A field test showed that 80.0 percent of 3 lane and 87.0 percent of 4 lane were appropriate for the mobile speed system. With the development of the mobile speed measuring system, it is expected to dramatically reduce the accidents caused by the speed of traffic. It is also expected to effectively operate equipment and manage the cost by improving manpower and providing improved enforcement accuracy, by contributing positively to public institution and public affairs.

• 한국전자파학회논문지
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• 제12권3호
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• pp.378-390
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• 2001

본 논문은 다중경로 라이시안 페이딩과 다중접속간섭이 함께 존재하는 단일 셀 내의 Multi-Carrier DS-CDMA 시스템은 오율 성능을 분석하고, 이를 Single-Carrier Ds-CDMA 시스템의 오율 성능과 비교하였다. 또한, 다중경로 페이딩과 다중접속간섭에 의하여 열화된 Multi-Carrier DS-CDMA 시스템의 성능 개선을 위해 부호화율이 1/2, 1/3 그리고 1/4인 콘볼루션 부호화 기법을 채용하여, 이로부터 얻어지는 Multi-Carrier DS-CDMA 시스템의 성능 특성을 알아 보았다. 분석 결과, 다중경로 페이딩과 다중접속간섭이 존재하는 채널에서 Single-Carrier DS-CDMA 시스템의 RAKE 수신기의 가지를 증가시키거나 Multi-Carrier DS-CDMA 시스템의 반송파의 수를 적정하게 선택함으로써 시스템의 사용자의 수를 결정할 수 있음을 알 수 있었다. 또한, 콘볼루션 부호가 적용된 Multi-Carrier CS-CCMA 시스템은 부호이득과 전력제한의 사이의 trade off를 고려하여 부호화율을 선택하여야 함을 알 수 있었다. 결과적으로 Multi-Carrier DS-CDMA 시스템은 반송파의 수가 증가할수록 처리이득은 감소하나 주파수 다이버시티 효과로 인하여 오율 성능이 개선되었으며, 낮은 칩율을 사용한 시스템의 구성이 가능함을 알 수 있었다.

• 한국통신학회논문지
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• 제26권12B호
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• pp.1637-1647
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• 2001

Multi-Code CDMA (MC-CDMA) 방식은 송신 시 여러 채널의 신호를 동시에 선형적으로 합하여 전송하므로 채널수가 증가할수록 신호의 PAPR(Peak to Average Power Ratio)가 증가하게 되어 증폭기의 비선형 특성에 의해 시스템 성능이 변화한다. 본 논문에서는 다중 레벨 신호에 대한 증폭기의 비선형 왜곡 특성을 분석하고, 증폭기의 비선형 특성에 의한 영향을 최소화하기 위해 다중 레벨 신호를 constant envelope 신호로 변환하는 Multi-Phase CDMA (MP-CDMA) 방식을 제안한다. 또한 다중 레벨 신호의 일정 레벨 이상은 잘라버리는 clipping 방식을 적용함으로써 레벨수의 증가에 따른 성능 저하 및 시스템의 복잡화를 줄이며 이로 인한 시스템 성능의 변화와 요구 전송 속도에 따른 최적의 clipping level을 연구한다.

• 한국태양에너지학회 논문집
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• 제31권1호
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• pp.1-7
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• 2011

This study was accomplished to evaluate the performance of Multi Effect Distillation(MED) for solar thermal desalination system. It was designed Multi effect distillation with $3m^3$/day capacity and Shell&Tube type heat exchanger. Also, The effective heat transfer of Shell&Tube heat exchanger was used Cu(90%)-Ni(10%) corrugated tube. The parameters relating to the performance of Multi Effect Distillation are known as hot water flow rate. The experimental conditions for each parameters were $18^{\circ}C$ for sea water inlet temperature, $6m^3$/hour sea water inlet volume flow rate, $75^{\circ}C$ for hot water inlet temperature, 2.4, 3.6, and $4.8\;m^3$/hour for hot water inlet volume flow rate, respectively. The results are as follows, Development for Multi effect distillation was required about 40kW heat and 35kW cooling source to produce $3m^3$/day of fresh water. Based on the results of this study, It makes possible to secure economics of desalination system with solar energy which is basically needed development of high efficiency fresh water generator.

• 대한산업공학회지
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• 제6권1호
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• pp.1-7
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• 1980

An exact solution technique for M/M/s multi-server demanding queue is introduced, and a general form of the curves representing service rates of the system is presented. As the number of customers in the system increases, the service rate is shown to increase initially, then decrease, and finally converge to a certain value. It is also shown that this phenomenon persists regardless of the numbers of servers and customer types.

• 한국통신학회논문지
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• 제39A권12호
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• pp.774-776
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• 2014

본 논문은 가시선 (line-of-sight) 성분이 지배적인 채널 환경에서 다중 사용자로의 정보 전송을 위해 이중 편파를 이용하는 다중 안테나 시스템을 제안한다. 이 시스템은 공간 및 편파 자원을 효율적으로 활용하여 기존의 단일 편파 안테나를 이용하는 MU-MIMO(multi-user multiple input multiple output) 시스템 보다 향상된 총 전송률을 제공할 수 있음을 보인다

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권4호
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• pp.1579-1602
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• 2020

In the design of production system, buffer capacity allocation is a major step. Through polymorphism analysis of production capacity and production capability, this paper investigates a buffer allocation optimization problem aiming at the multi-stage production line including unreliable machines, which is concerned with maximizing the system theoretical production rate and minimizing the system state entropy for a certain amount of buffers simultaneously. Stochastic process analysis is employed to establish Markov models for repairable modular machines. Considering the complex structure, an improved vector UGF (Universal Generating Function) technique and composition operators are introduced to construct the system model. Then the measures to assess the system's multi-state reliability and structural complexity are given. Based on system theoretical production rate and system state entropy, mathematical model for buffer capacity optimization is built and optimized by a specific genetic algorithm. The feasibility and effectiveness of the proposed method is verified by an application of an engine head production line.

• 전기학회논문지
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• 제65권11호
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• pp.1925-1930
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• 2016

Fuel cell power generation system, unlike conventional energy sources, converts chemical energy into electrical energy through electrochemical reaction of hydrogen and oxygen. This paper presents the control of interleaved multi-phase boost converter as the feasibility study on small-scale prototype electric railway vehicle application using fuel cell generation system. PSIM simulation program is to be used to implement the modeling of the electrical fuelcell as well as traction motor control with interleaved multi-phase boost converter. Comparing the input current ripple rate, two-phase interleaved boost converter is less than the boost converter. But the more multi-phase not less proportional to the ripple factor. we confirmed that the amplitude of the input current ripple rate of converter depend on duty ratio.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 금형가공,미세가공,플라스틱가공 공동 심포지엄
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• pp.13-16
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• 2005

For mass production, usually injection mold has multi-cavity which is filled through geometrical balanced runner system. Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed. These filing imbalances are one of the most significant factors to affect quality of plastic parts when molding plastic parts in multi-cavity injection mold. Filling imbalances are results from non-symmetrical shear rate distribution within melt as it flows through the runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during injection molding processing. This paper presents a solution of these filling imbalances through using 'runner core pin'. The runner core pin which is developed in this study creates a symmetrical shear distribution within runner. As a result of using runner core pin, a remarkable improvement in reducing filling imbalance was confirmed.