• 대한기계학회논문집
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• 제12권5호
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• pp.1197-1205
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• 1988

본 연구에서는 피스톤운동을 톱날파로 근사하였을 때 단열된 실린더를 갖는 스터링기관에 대한 해석적인 해를 구하고자 한다. 실제기관에서 피스톤운동은 기구 학적 구동기구에 따라 상이하지만 대략적으로 정현파가 되며, 이 경우에는 해석적인 해가 존재하지 않으므로 수학적으로 구간선형적인 톱날파로 근사하였다. 비록 이러 한 근사를 도입한 단열해석이라 하더라도 해석적인 해가 존재한다면 등온해석보다는 기관성능의 예측에 더욱 적합함은 당연하다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.377-378
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• 2002

In many dynamic systems, unwanted vibrations which may arise during operation of machines are costly in terms of reduction of performance and service life. Sometimes these risky oscillations endanger equipment and personnel. When hydraulic telescopic booms taken large mass are driven at slow speeds between the two pads, unstable oscillations occur through the stick-slip at the sliding parts and become more severe and saw-toothed. This paper supposes few models for the telescopic boom in the multi-degree of freedom system, and attempts a theoretical approach for the numerical analysis in its stick-slip condition, It was verified that this theoretical approach has an effect on estimate of stick-slip in the one-degree as well as multi-degree of freedom system.

• 한국정밀공학회지
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• 제12권7호
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• pp.138-147
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• 1995

The conventional PWM method, which was used in controlling the on-off valve, such as high-speed solenoid valve, was modulating the width of the pulse applied to the valve, by selecting arbitrary sampling time and modulating the duty-ratio in proportion to the error. However, in this method, a selection of long sampling time was inevitable and it was unable to get a high accuracy and a quick response. This study is for designing an appropriate controller for high-speed solenoid valve by proposing an improved duty-ratio modulation method using the Saw-toothed Carrier Wave which enables a short sampling time selection, high accuracy of control, and a quick response. Test which was carried out in the laboratory shows that transient and steady state response could be improved by PID controller.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.818-822
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• 2000

The low density, sustained high temperature strength and excellent resistivity to acid materials have made them strong candidate materials for future aerospace or medical applications. Nowadays their usage has already been broaden to everyday's commercial applications such as golf club heads, finger rings and many decorative items, Anticipating the general use of this material and development of the titanium alloys in domestic furnaces, the review and the study of the machining parameters for those alloys are deemed necessary. The present studies are concentrated to the machining parameters of the Ti-6Al-4V alloys due to their dominant position in the production of titanium alloys.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.156-160
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• 1997

This paper introdues the development of hydraulic cylinder with magnetic sensor detecting absolute and precise position for automation of excavator. The system which is developed can detect absolute position witha little displacement by using algorithm for recognizing datum points, 1/4 divider algorithm and high precision algorithm improved position precision and robustness to noise etc. The solenoid valve and PWM control using saw-toothed wave are used for absolute position control of cylinder, respectively

• 한국진공학회지
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• 제1권1호
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• pp.60-66
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• 1992

초격자와 다양자우물이 가질 수 있는 모든 구조에 대한 subband와 입자의 envelope 파동함수를 계산할 수 있는 방법을 제시하고 단순조성 초격자와 $\delta$-dopping 초격 자에 적용한 결과를 다른 방법의 계산결과와 비교하여 그 타당성을 검토하였다. 나아가서 기존의 방법에서 요구되었던 일정한 유효질량의 가정없이 graded gap 초격자에 적용하여 입자의 유효질량의 연속변화에 따른 subband 에너지와 파동함수를 계산하였다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 춘계학술발표회논문집(2)
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• pp.609-615
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• 1995

Chip machining에 의한 U$_3$Si 분말제조시 절삭가공조건이 분말 입도 분포에 미치는 영향을 조사하기 위하여 U$_3$Si ingot를 선반에서 초경공구를 사용하여 절삭속도 및 이송속도를 변화시키면서 chip을 가공하였고, 가공된 chip의 형상을 광학현미경으로 관찰하고 칩의 크기를 측정하였다. 모든 절삭조건에서 톱니모양의 칩(saw toothed chip)이 형성되었으며, 일정한 절삭속도에서 공구의 이송속도를 변화시켰을 때 이송속도가 증가함에 따라 칩 두께의 증가와 함께 chip segment의 폭도 증가하여 chip segment 의 크기가 뚜렷이 증가함을 보였다. 또한 chip segment의 크기는 절삭속도 보다는 공구의 이송속도에 크게 영향을 받는 것을 알 수 있었고 분말의 입도 분포에도 크게 영향을 미치는 것으로 나타났다.

• 한국응용곤충학회지
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• 제56권4호
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• pp.395-402
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• 2017

유기합성 농약의 과다사용은 환경오염, 살충제 저항성 발달, 비표적 생물에 대한 영향 등 부작용의 원인이 되고 있다. 유기합성 농약의 대체약제로 포유동물에 저독성인 식물기원 물질이 각광을 받게 되었다. 이란 서양가새풀(Achillea millefolium L.) 정유성분의 훈증독성은 국제적 저장작물 해충인 머리대장가는납작벌레(Oryzaephilus surinamensis L.)의 방제제로 연구된 바 있다. 이 식물 정유의 화학적 성분을 가스크로마트 그래피(MS)를 이용하여 분석하였다. 살충실험 결과 처리농도에 따라 유의한 살충률을 나타냈다. 처리농도와 살충률 간 양의 상관관계가 있었다. 반치사 농도(LC50)는 $17.977{\mu}l/L$ 이었다. 주요 성분은 1,8-Cineole (13.17%), nerolidol (12.87%), ${\alpha}$-cubebene (12.35%), artemisia ketone (6.69%), ${\alpha}$-terpineol (5.27%), alloaromadendrene oxide (4.71%) 및 borneol (3.99%) 이었다. 전체 동정된 화합물의 96.35%는 Terpenic 화합물로 monoterpene hydrocarbons (8.19%), monoterpenoids (44.23%), sesquiterpene hydrocarbons (21.69%) 및 sesquiterpenoids (22.24%)를 포함하고 있었다. 본 결과는 terpene이 풍부한 서양가새풀 정유가 머리대장가는납작벌레의 안전한 생물농약으로 고려될 수 있음을 보여주었다.

• 한국정밀공학회지
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• 제12권8호
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• pp.53-62
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• 1995

In recent years, the rapid development of the machine tool and tough insert has made metal removal rates increase, and automatic system without human supervision requires a higher degree reliability of machining process. Therefore the control of chips is one of the important topics which deserves much attention. The chip classification was made based upon standard deviation of the mean cutting force measured by a tool dynamometer. STS304was chosen as the workpiece which is known as the difficult-to-cut material and mainly saw-toothed chip produced, and the chip type according to the standard deviation of mean cutting force was classified into five categories in this experiment. Long continuous type chip which interrupts the normal cutting process, and damages the operator, tool and workpiece has low standard deviation value, while short broken type chip, which is favourable chip for disposal, has relatively large standard deviation value. In addition, we investigated the possibility that the chip type can be predicted analyzing the relationship between chip type and cutting condition by the trained neural network, and obtained favourable results by which the chip type can be predicted with cutting conditon before cutting process.

• 한국정밀공학회지
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• 제8권3호
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• pp.44-54
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• 1991

A Study was made on falnk wear in carbide tools in turning SUS304 steel. When an austenitic stainless steel (SUS304 steel) is cut with the tool, saw-toothed chip are produced. It is found that machining SUS304 steel would make a tool worn fast. For increasing productivity, tool wear has to be predicted and controlled. An amended cutting geometry consisting of a negative rake angle ($-6^{\circ}$ ) and a high clearance angle ($-17^{\circ}$ ) is proposed for decreasing carbide tool wear (flank) in the machining of SUS304 steel. The amended cutting geometry is found to make the flank wear lower than a general cutting geometry (rake angle $6^{\circ}$ , clearance angle $5^{\circ}$). The effects of the three cutting variables (cutting speed, feed, tool radius) on the flank wear analyzed by fiting a simple first-order model containing interaction terms to each flank wear parameter by means of regression analysis and the predicted from first-order regression analysis model equation of flank wear.