• 한국안전학회지
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• 제9권4호
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• pp.17-28
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• 1994

Chip breaking is important in lathe work for maintaining good surface of the products and safety of operator. The purpose of this study is to investigate the performance of chip breaking and chip shape resulted from the carbide inserts with grooved type and obstruction type chip breaker. Experiments have been performed under the following cutting conditions, (1) constant cutting speed with variable depth of cut and feed rate, (2) constant depth of cut with variable cutting speed and feed rate. Also, the flying distance of chip and it's distribution have been investigated. As a results, good performance of chip breaking can be obtained for small radius of curvature and land width of grooved type chip breaker. And the thickness of chip increase with the increase of feed rate and decrease of cutting speed, and the chip breaking becomes easier with the increase of chip thickness due to the large deformation rate. Obstraction type chip breaker shows better performance of surface roughness than the grooved type. The flying distance of the chips over 90% are less than 1 meter, and the distance decreases as the feed rate decreases.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.643-650
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• 2002

The large planar failure has occurred in a rock cut slope of highway construction site in Boeun. This area is considered as unstable since the discontinuities whose orientations are similar to the orientation of the failure plane, are observed in many areas. Therefore, several analysis techniques such as SMR, stereographic analysis, limit equilibrium, numerical analysis, which are commonly used in rock slope stability analysis, are adopted in this area. In order to analyze the stress redistribution and nonlinear displacement caused by cut, which are not obtained in limit equilibrium method, the UDEC and shear strength reduction technique were used in this study Then the factors of safety evaluated by shear strength reduction technique and limit equilibrium were compared. In addition, the factor of safety under fully saturated slope condition was calculated and subsequently, the effect of the reinforcement was evaluated.

• 한국기계가공학회지
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• 제17권6호
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• pp.61-67
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• 2018

The face milling cutter, which is mainly used for the face milling, is used to cut the Carbon steel(SM20C) in the machining center for 5 times and 10 times respectively. This study clarify the dimensional accuracy characteristics according to the number of fine machining varied the condition of cutting depth, table feed speed and spindle speed. Cutting depth is varied 0.05~0.2mm, table feed speed is varied 0.05~0.2mm/min and spindle speed is varied 1500~2500rpm. As a result, the dimensional accuracy was stable 6 times machining with table feed speed 150mm/min and 10 times machining with table speed 100mm/min and cutting depth 0.05mm regardless times of machining.

• 한국지반공학회논문집
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• 제17권6호
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• pp.173-180
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• 2001

지진동으로 인한 개착식터널의 동적 거동특성을 파악하기 위해 Prototype터널 폭이 약 14.2m, 높이가 약 8.5m를 1/40sca1e로 축소제작한 모형체의 진동대 실험을 수행하였으며 본 실험에서는 터널의 토피고 및 원지반의 경사각에 따른 영향을 분석하였으며 이를 동적수치해석결과와 비교 분석하였다. 진동대 실험결과 터널의 토피고가 증가할수록 터널에 발생되는 응력 및 가속도는 감소하는 것으로 나타났으며 이는 터널의 설치심도가 증가할수록 주변지반의 구속효과가 증가하기 때문인 것으로 판단된다. 또한 원지반의 경사가 완만할수록 터널에 발생되는 응답치는 증가하는 경향을 보이고 있는데 이는 지진동으로 인한 주변지반의 구속효과가 원지반의 영향 보다는 되메움토사의 영향을 지배적으로 받기 때문인 것으로 판단된다. 또한 진동대실험결과 및 상시조건의 구조해석결과와 비교하면 터널의 토피고가 터널직경의 1배(1D)이상 확보되는 조건일 경우, 지진동이 터널에 미치는 영향이 적은 것으로 나타났다.

• 화훼연구
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• 제19권4호
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• pp.206-211
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• 2011

절화 국화 '백마'의 수확 후 수송조건 및 생장조절제 처리가 선도유지 및 품질에 미치는 영향을 알아보기 위하여 절화 국화 '백마'를 공시재료로 사용하였다. 수송조건 실험 결과 저장온도에 따른 절화 품질은 $5^{\circ}C$ 저온 저장시 상온(대조구)저장과 $20^{\circ}C$ 저장 보다 효과적임을 확인하였다. 또한 수송방법에 따른 절화 품질은 물올림 처리 후 수직 수송방법이 다른 처리구에 비하여 우수한 효과를 나타내었다. 특히 생장조절제 uniconazole $10mg/L^{-1}$ 문무 처리는 개화를 지연시켜 선도를 유지시켰으며 daminozide 1,000배 분무 처리는 꽃목 굽음을 지연시켜 절화 국화 품질 유지에 우수한 결과를 나타내었다.

• 한국구조물진단유지관리공학회 논문집
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• 제6권1호
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• pp.205-212
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• 2002

The deterioration rate of concrete structures in urban area is accelerated due to rapid urbanization and environmental pollution. Repair materials and methods newly introduced in Korea should be investigated whether they are appropriate for the urban environment in Korea. The creek concrete structures are exposed in severe environmental condition than others. Based on these background in mind, the study is focused on evaluation of performance on repair materials used to rehabilitate creek concrete structures. To evaluate the performance of repair materials, four kinds of repair materials were selected based on polymer emulsion. This experimental study was conducted on fundamental performance such as setting time, compressive strength, bending strength, bonding strength, thermal expansion coefficient, and durability performance such as chloride diffusion, carbonation, chemical attack, and steel corrosion rate. On the basis of this study, the optimal repair material which is proper to the environment condition can be selected and service life of creek concrete structures can be extended. As a result, the life cycle cost can be reduced and the waste of material resources will be cut down.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.20-27
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• 2003

In this paper, the fuel transport characteristics during transient condition was studied by using a Fast Response Flame Ionization Detector(FRFID). The quantitative measurement method for the inducted fuel mass into cylinder is studied. The inducted fuel mass into the cylinder was estimated by using calculated air-fuel ratio by hydrocarbon concentration of cylinder and air flow model. In order to estimate the transportation of injected fuel from the intake port into cylinder, the wall wetting fuel model was used. The two coefficient $\alpha$,$\beta$) of the wall-wetting fuel model was determined from the measured fuel mass that was inducted into the cylinder at the first cycle after injection cut-off To reduce an air/fuel ratio fluctuation during rapid throttle opening, the appropriate fuel injection rate was obtain from the wall wetting model with empirical coefficients. Result of air/fuel ratio control, air/fuel excursion was reduced.

• 한국정밀공학회지
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• 제20권8호
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• pp.30-38
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• 2003

High-speed machining is one of the most effective technology to enhance productivity especially for hardened die material. High-speed machining can give great advantages for machining of dies and molds. But selection of machining condition is very difficult because of complicated machining mechanism. This paper presents the selection of machining condition in high-speed machining of STD11. Depth of cut, feed rate and spindle revolution are control factors. The effect of the control factors on surface roughness and machining error in Z-direction is discussed to improve machining accuracy.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.341-344
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• 2006

LED chips are produced by cutting the sapphire on which GaN is evaporated. To cut the sapphire wafer into each LED chip, at first the wafer is scribed by diamond tool. To get the sharp groove shape for the nice cutting plane it is important the diamond tool shape, load, etc when the wafer is scribed. Here we tried to simulate the scribing process and get the scribing condition to reduce the wear rate of diamond tool for the sharp groove shape.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.108-113
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• 2005

In this study, rotary type diamond dressing system for ultra-precision centerless grinding for ferrule was developed at the first time and experiments were conducted with AE sensor and hall sensor system to verify the optimum dressing condition for ultra-precision centerless grinding for ferrule. The correlations with the condition of dressing are evaluated by AE signal analysis with root mean square (RMS) and frequency analysis. And current signals from hall sensor are also studied as a factor of dressing optimum condition selection. Dressing process was conducted to investigate the effects of depth of cut, rotating speed, and the number of overlap to select the optimum condition of rotary dressing system of ultra-precision centerless grinding machine for ferrule fabrication. In order to verify the optimum condition of dressing, AE and current signals were compared with the surface quality of dressing wheel and grinding wheel for ultra-precision ferrule grinding. All of these experiments were completed by Taguchi Methodology to reduce experimental time. Hence, the optimum condition of rotary dressing system for ultra-precision centerless grinding for ferrule fabrication can be selected following to the experiment result from signals of AE and hall sensor.