• Journal of Advanced Marine Engineering and Technology
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• 제29권6호
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• pp.618-627
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• 2005

In this paper, we have compared and analyzed the performance of high amplifier using Doherty technique to improve linearity and efficiency of base station and repeater Power amplifier for WCDMA. This Doherty amplifier implements with 3dB branch line coupler and $90^{\circ}C$ transmission line The phase offset line is designed to maintain the high linearity and efficiency at the low efficiency Period of the power amplifier CW 1-tone experimental results at the WCDMA frequency $2.11{\sim}2.17GHz$ shows that Doherty amplifier which achieves power add efficiency(PAE) of 50% at 6dB back off the point from maximum output power 52.3 dBm, obtains higher efficiency of 13.3% than class AB Finding optimum bias Point after adjusted gate voltage, Doherty amplifier shows that $IMD_3$ improves 4dB.

• 전자공학회논문지A
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• 제28A권10호
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• pp.782-790
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• 1991

In this paper, we implement the function of the IEEE802.2LLC(logical link control) sublayer one of the 7layers in MAP(manufacturing automation protocol), a standard communication protocol for manufacturing automation. With the assembly language we designed the class 3 function based on the IEEE standards and verified on the network adaptor hardware. In this experiment, we tested the function using the simplified variables considering that the retransmission value was chosen to be 1 and the life-time of the transmission variable infinite. According to the result of the service procedures, we confirmed that user data were transmitted to the corresponding station without any error.

• 한국통신학회논문지
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• 제21권6호
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• pp.1501-1509
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• 1996

Mobile stations can be classified by the transmission power level in CDMA system. Different performance parameters will be given to each class of mobile stations so that the appropriate quality ofservices can be provided. In this paper, it is assumed that there are two clsses of mobile stations. with the classification of mobile stations, analytical models are presented for the estimates of the reverse link capacity and the blocking probability. From the model for the reverse link capacity, the maximum number of each class of mobile stations to be served is derived. It is shown that $E_{b/}$I reduction of 1 dB allows the capacity to be increased by 25% and the data transmission rate and the power control accuracy have a significant effect on the reverse link capacity and the blocking probability. Simulation results are provided for validating the anlaytical estimates of the blocking probability.ocking probability.y.

• 대한산업공학회지
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• 제18권2호
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• pp.109-121
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• 1992

In this paper, we address a layout design problem for determining a K-class-based dedicated storage layout in an automated storage retrieval system. K-class-based dedicated storage employs K zones in which lots from a class of products are stored randomly. Zones form a partition of storage locations. Our objective function is to minimize the expected single command travel time, which is expressed as a set function of space requirements for zones, average demand rates from classes, and one-way travel times from the pickup/deposit station to locations. We construct a heuristic algorithm based on analytical results and a local search method, the methodology deveolped can be used with easily-available data by warehouse planners to improve the throughput capacity of a conventional warehouse as well as an AS/RS.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.511-518
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• 2008

The Engineering Test Satellite VIII(ETS-VIII) of Japan Aerospace Exploration Agency(JAXA) uses a 20mN class xenon ion engine subsystem(IES) for North-South Station Keeping(NSSK). The IES was modified for a larger satellite with longer lifetime based on the former IES. ETS-VIII, a three-ton class geosynchronous satellite with 10 years bus lifetime, was launched 18 Dec. 2006 JST; it reached the planned orbit and all bus systems were checked out. The IES showed good results and is now under normal operation. The total accumulated operation time of the IES in orbit was about 2300 hours till $19^{th}$ Dec. 2007.

• Nuclear Engineering and Technology
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• 제45권4호
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• pp.459-468
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• 2013

During a station blackout (SBO), the initiating event is a loss of Class IV and Class III power, causing the loss of the pumps, used in systems such as the primary heat transporting system (PHTS), moderator cooling, shield cooling, steam generator feed water, and re-circulating cooling water. The reference case of the SBO case does not credit any of these active heat sinks, but only relies on the passive heat sinks, particularly the initial water inventories of the PHTS, moderator, steam generator secondary side, end shields, and reactor vault. The reference analysis is followed by a series of sensitivity cases assuming certain system availabilities, in order to assess their mitigating effects. This paper also establishes the strategies to mitigate SBO accidents. Current studies and strategies use the computer code of the Integrated Severe Accident Analysis Code (ISAAC) for Wolsong plants. The analysis results demonstrate that appropriate strategies to mitigate SBO accidents are established and, in addition, the symptoms of the SBO processes are understood.

• 한국토양비료학회지
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• 제19권4호
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• pp.283-289
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• 1986

논토양(土壤)에 수도(水稻)를 포함(包含)하여 그 전후작(前後作)으로 밭작물(作物)을 다모작(多毛作) 할 경우에 토양종류별(土壤種類別) 적성정도(適性程度)를 추정(推定) 할 수 있는 논토양다모작적성등급(土壤多毛作適性等級)을 구분(區分)코자 기초시험(基礎試驗)을 실시(實施)하고 적성등급구분(適性等級區分) 기준(基準)을 설정(設定)하였다. 기초시험결과(基礎試驗結果)는 전보(前報)에서 논(論)하였고 구분기준(區分基準) 및 주요결과(主要結果)는 다음과 같다. 1. 적성등급(適性等級) 구분요인(區分要因)은 잠재생산력을 대표(代表)한 토성(土性) 및 배수등급(排水等級), 화학적특성(化學的特性)(표토염농도(表土鹽濃度), 및 심토(心土)의 반응(反應)), 환경조건(環境條件)(경사도(傾斜度) 및 온량지수(溫量指數)) 그리고 지하수위(地下水位) 및 토양모재(土壤母材) 등(等)을 선택(選擇)하여 연역(演繹) 귀납(歸納) 절충식(折衷式) 인자별가중치(因子別加重値) 상승(相乘) 상가복합법(相加複合法)에 의한 이론적(理論的) 최상치(最上値)가 100 점(點)이 되도록 하였다. 91 점이상(點以上)인 토양(土壤)을 I급지(級地)로 하고 60 점이하(點以下)인 토양(土壤)을 V급지(級地)로 하되 10 점(點) 단위(單位)로 등분(等分)하였으며 등급별(等級別) 제한인자(制限因子)는 "물리성(物理性)" "화학성(化學性)" 및 "경사도(傾斜度)" 등(等) 3가지로 하되 2개까지 병기 가능(可能)토록 하였다. 2. 온량지수(溫量指數) 110 이상(以上)인 대부분(大部分)의 영남지역(嶺南地域)은 I급지(級地)가 19%, II급지(級地) 22.7%, III급지(級地) 44.7%, IV급지(級地) 11.5% 그리고 V급지(級地)가 2.1%로서 전국(全國)의 논토양(土壤) 급지별(級地別) 분포비율(分布比率)보다는 상급지비율(上級地比率)이 약간 높았다. 3. 토양별(土壤別) 총득점(總得點)과 생산력지수간에는 유의성(有意性)($r=.922^{**}$)이 인정(認定)되어 기준(基準)의 적합도(適合度)가 높은 것으로 볼 수 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제16권5호
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• pp.635-638
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• 2003

Japanese Black cattle (Wagyu) are fed for a long period to produce high quality beef, however, extended feeding often causes inefficiency and greater environmental load mainly derived from their manure. The objectives of this study were to analyze changes in feeding length by listing breeding values (BVs) at calf markets and the relationships between BVs and carcass characteristics of 4,052 Japanese Black cattle, and to examine the feasibility of optimizing feeding length by referring to listed BVs. BV classes A, B, and C were defined based on BVs of cows in Shimane Prefecture as follows: an upper quarter of BVs was classified as A, a second quarter as B, and under the average as C. For cattle sold at calf markets in the first term of 1996, just before the start of BV listing, the feeding length of cattle with class B BVs for the beef marbling standard (BMS) was longer (p>0.05) than that of class A cattle. However, in the second term of 1996, just after the start of BV listing, the feeding length of class B cattle became shorter (p<0.001) than that of class A cattle. Then, the feeding lengths of both classes showed no significant differences. Feeding lengths of both class A and B BVs for carcass weight (CW) changed similarly to the corresponding BV classes for BMS. The analysis of the relationships among the listed BV classes and the actual carcass characteristics showed that class A cattle had a higher (p<0.001) BMS than class B cattle, and that the higher-class cattle had a heavier CW (p<0.05). On the basis of previous reports, the cattle, particularly those with lower genetic marbling ability, seem to only increase marbling at markedly low efficiency for a few months before slaughter. Therefore, the finding that carcass characteristics corresponded to their class of BVs suggests that an optimum feeding length based on listed BVs not only increases the efficiency of beef production, but also reduces the environmental load.

• 한국가스학회지
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• 제3권2호
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• pp.77-84
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• 1999

본 연구에서는 경기도 부천시 OOO소재의 위험물 판매 취급소인 XX상사를 표준모델로 선정하여 여기서 취급하는 제 4류 위험물에 대한 위험성 평가를 실시하고 아울러 바로 길건너 맞은편의 약 20m 거리에 위치한 LPG 충전소에 대한 위험성 평가도 아울러 실시하였다. 본 연구에서의 위험성평가를 위해서는 PHAST와 Super-Chem 소프트웨어를 이용하였으며 이러한 Simulation 결과를 이용하여 분석한 결과 물질 중 아세톤의 경우 TNO 모델에 의한 복사열 평가에 의해 설비에 손상을 줄 수 있는 $37.5kw/m^2$에 해당하는 거리는 PHAST 모델의 경우 68.51m에 이르렀으며, Super-Chem 모델의 경우는 40.9,3m에 이르렀다. LPG 충전소에 대한 Simulation 결과 Fireball 지름은 125.2m에 이르며 Fireball의 높이는 206.2m에 이른다. 또한, 그 지속시간은 11.28초로 계산되었다.

• 대한산업공학회지
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• 제39권3호
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• pp.172-182
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• 2013

In this study we consider a flow line CONWIP system in which two types of product are produced. The processing times of each product type at each station follow an independent exponential distribution and the demands for the finished products of each type arrive according to a Poisson process. The demands that are not satisfied instantaneously are either backordered or lost according to the number of unsatisfied demands that exist at their arrival instants. For this system we develop an approximation method to obtain the performance measures such as steady state probabilities of the number of parts of each product type at each station, mean waiting times of backordered demands and the proportion of backordered demands. For the analysis of the proposed CONWIP system, we model the CONWIP system as a two class closed queueing network with a synchronization station and analyze the closed queueing network using a product-form approximation method for multiple classes developed by Baynat and Dallery. In the approximation method, each subsystem is analyzed using a matrix geometric method. Comparisons with simulation show that the approximation method provides fairly good results for all performance measures.