• 한국정밀공학회지
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• 제20권10호
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• pp.31-40
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• 2003

In this paper, optimal cutting condition to minimize the form error in side wall machining with a flat end mill is studied. Cutting forces and tool deflection are calculated considering surface shape generated by the previous cutting such as roughing. Using the form error prediction method from tool deflection, optimal cutting condition considering form accuracy is investigated. Also, the effects of tool teeth number, tool geometry and cutting conditions on form error are analyzed. The characteristics and the difference of generated surface shape in up and down milling are discussed and over-cut free condition in up milling is presented. Form error reduction method through successive up and down milling is also suggested. The effectiveness and usefulness of the presented method are verified from a series of cutting experiments under various cutting conditions. It is confirmed that form error prediction from tool deflection in side wall machining can be used in optimal cutting condition selection and real time surface error simulation for CAD/CAM systems. This study also contributes to cutting process optimization for the improvement of form accuracy especially in precision die and mold manufacturing.

• 소음진동
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• 제6권4호
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• pp.503-511
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• 1996

There is a tendency of using the resilient mounting system to control the structure born noise transimitted from a engine of which weight is comparatively light and of which speed is comparatively high. According to recent reports, the resilient mounting system is applied to control the vibration of a engine running up to 300 - 400 R.P.M.. Furthermore, the resilient system is also used to the ships such as marine exploring ships, fishing boats, and military vessels. It is not desirous to apply the results for the resilient mounting systems of automobile engines to the controls of the vibrations of marine engines. Marine engines are worked under the idle speed in port and are operated up to the maximum contineous revolution at sea(running up condition). And marine engines are usually worked in inevitable conditions such as a misfire and a cut-off cylinder operating condition. Concerning the above running conditions, a resilient mounting system should be designed in the case of marine engines. In this paper, we studied the effect of engine's misfire on the resilient mounting systems. And the influences of design parameters, such as dynamic characteristics and fitting angles of resilient rubber mountings, were also investigated respectively on the single and double resilient mounting systems.

• Journal of the Korean Wood Science and Technology
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• 제10권3호
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• pp.133-134
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• 1982

This experiment has been made to investigate the absorption of watersoluble zinc chloride by Pinus densiflora S. et Z. at different moisture content, under soaking process, to decide the optimum content condition for the maximum absorption of zinc chloride by the wood tested and to investigate the concentration of zinc chloride affecting each moisture content of wood. Material was cut in the Dept. of Forest, College of Agr. S.N.U. Suwon, Korea. Sample was divided into sap and heartwood group and cut $2{\times}2{\times}2\;cm$ in size, having exact three dimensions, using the part of D.B.H. The numbers of sample were 20 pieces for each moisture content condition for both sap and heartwood. Especially, the samples were protected from exposure to keep moisture content in green condition. The ranges of moisture content tested were as the table 3 and 4. The conclusions were as follows: 1. With 3% zinc chloride solution, the rate of absorption decreased with the time increased, if the air seasoned Korean red pine (Pinus densiflora S. et Z.) was treated in steeping process. Initial absorption for 30 minutes was more than 50% of total absorpon for 24 hours. 2. Rate of absorption was same under the green condition, while rate of absorption under the moisture content 7 to 30% varied. 3. Although it was not quite proportional change in the absorption with the difference of moisture content, the great change in the absorption occured by seasoning. With exception sap green condition, sapwood twice more permeable than the heartwood in the oven dried condition and it has been observed the nearly same amount of absorption at the moisture content of 7%, 10% and 15% respectively in heartwood. 4. It was better from water in wood from view-point of absorption of zinc chloride solution, but it was difficult practically to obtain the smallest moisture content, and then it was decided that values of allowable moisture content, on the basis of mean absorption, were 15% to 20% in the sapwood, and in the heartwood, 10% to 15%. The mean absorption for each moisture content in the sap and the heartwood were as following. 5. In general, the concentration of zinc chloride after steeping was nearly same between moisture content and sap and heartwood respectively.

• 한국자동차공학회논문집
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• 제19권2호
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• pp.26-34
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• 2011

Hybrid powertrain systems have been developed to improve the fuel efficiency of internal combustion engines. In the case of a parallel hybrid powertrain system, an engine and a motor are directly coupled. Because of the hardware configuration of the parallel hybrid system, friction and the pumping losses of internal combustion engines always exists. Such losses are the primary factors that result in the deterioration of fuel efficiency in the parallel-type hybrid powertrain system. In particular, the engine operates as a power consumption device during the fuel-cut condition. In order to improve the fuel efficiency for the parallel-type hybrid system, cylinder deactivation (CDA) technology was developed. Cylinder deactivation technology can improve fuel efficiency by reducing pumping losses during the fuel-cut driving condition. In a CDA engine, there are two operating modes: a CDA mode and an SI mode according to the vehicle operating condition. However, during the mode change from CDA to SI, a serious fluctuation of the air-fuel ratio can occur without adequate control. In this study, an air-fuel ratio control algorithm during the mode transition from CDA to SI was proposed. The control algorithm was developed based on the mean value CDA engine model. Finally, the performance of the control algorithm was validated by various engine experiments.

• 화훼연구
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• 제18권4호
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• pp.244-250
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• 2010

본 연구는 국화 '신마' 품종의 플러그 묘 생산에 있어서 삽수의 조건이 지상부 생육과 발근 및 정식 후의 절화 생육에 미치는 영향을 알아보고자 실시하였다. 삽수에 부착된 잎을 전부 제거한 처리는 지상부 생육이 가장 불량하였고, 전혀 발근이 안 되었다. 잎을 4~6개를 부착하여 삽목하는 것이 지상부 생육 및 발근에 효과적이었다. 삽수길이는 5~7 cm 처리에서 지상부의 무게가 무거웠으며, 발근에 있어서는 다른 처리에 비하여 5 cm 처리에서 뿌리의 무게가 가장 무거웠고, 뿌리수가 가장 많았다. 삽수 굵기가 굵을수록 지상부 생육과 발근이 양호하였다. 삽수에 부착된 엽수가 4~6개인 처리에서 절화장이 길었으며, 줄기의 굵기도 컸다. 삽수의 굵기가 3.2 mm 처리에서 절화장이 가장 길었다. 따라서 국화 '신마' 플러그 묘 생산시 삽수의 굵기가 3.2 mm 정도의 5 cm 길이의 삽수에 4장의 잎을 부착하여 삽목하는 것이 묘의 생육 및 발근에 효과적이고, 정식 후 절화의 생육에도 적합하였다.

• 한국정밀공학회지
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• 제27권5호
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• pp.14-21
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• 2010

In this study, presintered low purity alumina ceramics were machined with various tools to clarify the effects of the tool material, cutting condition and tool geometry on machinability. The main conclusions obtained were as follows. (a)The wear of tungsten carbide tool becomes smaller with the increase of the feed and clearance angle, and with the decrease of rake angle, especially exhibiting considerably smaller wear with both the decrease of rake angle and the increase of clearance angle. (b) So far as turning the ceramic presintered at low temperature, the diamond tool shows the best performance with higher feed. (c) The effect on the tool wear of the feed, clearance angle and rake angle becomes smaller in turning the ceramic presintered at higher temperature. (d) The tool wear is not severely affected by the depth of cut.

• 멤브레인
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• 제9권4호
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• pp.193-201
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• 1999

기존의 정수처리 공정인 응집 침전 과정을 대체하여 분리막을 이용한 상수처리 시스템의 개발을 목적으로한다. 따라서 4가지 형태의 정수처리 공정과 분리막의 분획 분자량을 변화시켰을 때 막 투과수의 변화와 안정적이며 높은 투과수를 얻기 위해 필요한 운전 조건의 최적화를 실험하였다 실험결과 한외여과막이 정밀여과막보다 막 투과수 감소경향이 완만했으며 초기 투과수 회복율은 더 높았다. 수질 분석의 결과 한회여과막이 정밀 여과막보다 우수하였지만 전처리에 의한 차이는 나지 않았다. 운전 조건에 따른 flux 는 온도, 선속도가 높을수록 압력이 낮을수록 flux 감소율이 적은 경향을 나타내었다.

• 한국작물학회지
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• 제50권3호
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• pp.191-196
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• 2005

이 실험은 보리의 붉은곰팡이병에 대한 정밀하고 효율성이 높은 검정체계를 확립하고, 이를 토대로 저항성 품종을 선발하고자 실시하였다. 이를 위해서 온$\cdot$습도 조절이 가능한 붉은곰팡이병 전용 습실 검정상을 제작하여 포트 재배한 식물체에 3개의 다른 접종시기별(출수기, 출수후 3일, 출수후 5일)로 SCK-O4 균주의 분생포자 현탁액 $5.0\times10^5$ macroconidia $mL^{-1}$를 각각 접종하고 4개의 다른 기간 동안 습실처리(1, 3, 5, 7일)를 하여 각 처리별 이병 정도를 평가하였다. 또한 절단이 삭검정법을 통한 대량검정법도 검토하였다. 1. 습실 검정상 내에서의 붉은곰팡이병 발병률은 접종시기에 따라 차이를 보이지 않았으나, 습실처리기간에 따라서는 유의한 차이를 보였다. 2.습실 검정상을 이용한 붉은곰팡이병의 저항성 검정은 출수기에 접종하고 습실 검정상 내에서 7일간 유지하여 판정하는 것이 가장 효율적이었다. 3. 포트검정법과 절단이삭검정법의 검정방법간 발병 정도는 고도로 유의한 정의 상관$(r=0.892^{***})$을 보였다. 4. 저항성 품종은 진광보리, 부흥, Atahualpha92, Chevron-b, Gobernadora-d 및 MNBrite-c 등이 선발되었으며, 이들 품종은 2개의 검정시기에서 일정한 저항성을 나타내었다.

• 화약ㆍ발파
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• 제13권4호
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• pp.39-46
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• 1995

This report was arrangemented and analysed by blasting previous instance of Nocsan, developing area of national factory town in Pusan since 1994. 11. our team have acquired sequential blasting machine which is used at open blasting sites of other countries. The result of study is that follow ; in case of delay electric detonator of Korea, it is possible to use 300 ~600 blasting holes in 2 charge per delay. But in our experience, it is best condition to use 100~200blasting holes at 1 charge per 1 delay.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 추계학술대회 논문
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• pp.58-63
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• 1996

A study is drawn up its result's tables and graphs by measuring tools(outside micrometer cylinder gauge and dial caliper gauge) on the difference of diameter volumes from before-discharge and after-discharge under 52 Kind's experimental condition by cupper and graphite electrode of CNC EDM. The EDM is attached with A.V.R. and memory scope for keep up accuracy and the fixed table of work piece is used in order to eliminate the noise by the internal resistance of it and forcing to eradicate the discharge liquid. It is analyzed cutting conditions to compare its wave value and pulse time.(Ton Toff) through voltage and current for decreasing working error.