• Journal of Biosystems Engineering
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• 제23권2호
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• pp.135-146
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• 1998

The equation to predict the soil temprature of Pusan and Chinju city as a function of time and soil depth for the geothermal energy utilization system and agriculture was devised. The equation was $T(x,t)\;=\;Tm\;-\;To{\cdot}ExP(-{\xi}){\cdot}cos{{\omega}{\cdot}[t-to-x/(2{\cdot}{\alpha}{\cdot}{\omega})^{0.5}]}$ with the soil thermal diffusivity, ${\alpha},\;of\;0.4\;\textrm{m}^2/day,\;0.0375\;\textrm{m}^2/day$ and phase zero point, to, of 24 days, 22.4 days in Pusan and Chinju city, respectively, during ten years from 1987 to 1996. The predicted and measured soil temperatures agreed well with the coefficient of determination of 0.95 at the soil depth of 0.0, 0.5, 1.0, 3.0, 5.0 m. The maximum and minimum temperature in Pusan 3.7, $30.1^{\circ}C$ at soil surface and 14.3, $18.0^{\circ}C$ at the depth of 5.0 m. The total mean temperature of soil in Pusan and Chinju city was about 16.3, $16.0^{\circ}C$, respectively.

• Journal of the Korean Wood Science and Technology
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• 제39권3호
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• pp.252-257
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• 2011

국내에서 생산되는 목재에 대한 나사못 유지력을 기존의 식으로부터 수정된 예측 식으로 나타내기 위해 나사 못 뽑기 실험을 실시했다. 본 연구에 사용된 나사못은 No. 6, No. 8 및 No. 10이었다. 예측 식은 길이가 서로 다른 No. 8 나사못의 실험결과와 매우 일치하였다. 나사못 유지력의 예측 식은 나사못의 직경과 관입길이 및 목재비중의 함수로 나타냈다. 예측 식은 나사못 길이가 25와 30 mm에서 5% 이내로 작게 예측되었으나 18과 38 mm에서 큰 값을 보였다.

• 한국정밀공학회지
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• 제15권10호
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• pp.34-40
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• 1998

The burr produced on piece part edges in machining operations must be removed for most parts to function effectively. Although considerable cost have been expended in improving deburring methods, little energy has been applied toward minimizing burrs. This study has been carried out to prevent the burrs produced on pure aluminium under various working condition and specimen shape in turning operations. The computer image processing system was used for measurement of size of burr, such as burr length, burr depth and burr area. The size of burr showed a decreasing tendency with the increase of rake angle and side cutting angle but it increased rapidly with the increase of depth of cut and the cutting speed has no effect on size of burrs. The size of burr rapidly decreased with the increase of edge angle and burrs are not occurred if edge angle is over 80$^{\circ}$.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1360-1365
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• 2006

In this paper the vibration analysis of cantilever beams having a concentrated tip mass and an open crack are performed. The influences of a concentrated tip mass, the crack depth, and the crack position on the natural frequencies of the cracked cantilever beam are investigated by a numerical method. The cracked cantilever beam is modeled based on the Euler-Bernoulli beam theory. The flexibility due to crack is calculated using a fracture mechanics theory. The crack is assumed to be opened during the vibrations. The results obtained by the present method were compared with experimental results to verify the theory. As inspected, as the crack depth and the concentrated tip mass increase, the natural frequencies of the beam decrease. In general, the natural frequencies of the cantilever beam are more sensitive to the depth of the crack than the position of the crack.

• 물과 미래
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• 제9권1호
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• pp.101-105
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• 1976

본 연구는 수공구조물의 내용년수와 안전율을 고려한 서울지방의 단시간 확률항우량을 산정한 것이다. 서울지방에서 기왕의 자기우량기록지(1915년∼1974년까지 60년간분)를 모집하여 단시간 항우계속시간(10분∼120분)별해년 최대치를 적출 하였다. 적출된 항우량자료는 빈도해석을 통하여 자료집단별 도수를 결정한 후 그 도수가 정규화되도록 시도하였으며 정규분포의 적합도검정 방법에 있어 유의수준 5%로 보고 X2-test를 행하여 최적분포별을 설정하였다. 설정된 최적분포형의 매개변수(평균치, 표준편차)를 적용하여 본 논문에서 유도제시한 Graph에 의하여 확률항우량을 도해법에 의하여 구하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1338-1345
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• 2009

Although rock excavation is necessary for the effective utilization of urban space, most conventional rock excavation methods, including the blasting method, cause high noise and vibration. Meanwhile, if a high pressure waterjet system is applied to excavate underground spaces in urban areas, the public grievance can be reduced by low noise and vibration. In this study, an abrasive waterjet system is designed and developed to study the influence of various performance parameters such as jet pressure, nozzle traverse speed, stand-off distance, or abrasive feed rate on waterjet excavation performance in laboratory. Using the developed waterjet system, rock drilling characteristics are identified by measuring drilling depths as a function of the jet exposure time. The drilling depth linearly increases with increasing the jet exposure time(under 60sec). Rock cutting characteristics are also obtained with various jet pressures(1600~3200kg/$cm^2$) and nozzle traverse speeds(1.9~14.1mm/s): The cutting depth is nonlinearly related to the jet pressure and traverse speed. Indeed, the cutting depth increases with an increase in the jet pressure and a decrease in the nozzle traverse speed. This trend can be explained by energy transferring/loss mechanism.

• 한국결정성장학회지
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• 제10권4호
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• pp.297-301
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• 2000

H와 Li의 양자교환법에 의해 평면도파로와 channel도파로를 $LiNbO_3$단결정 기판위에 구현하였다. 양자원으로 피로인산을 사용하였고 평면도파로의 모드들에 대한 유효굴절률을 측정하였으며 반응시간과 반응온도로부터 광도파로의 깊이와 계단형 형태의 굴절률 변화에 대한 식을 구하였다. 이 식에서 구한 단일모드 도파 조건으로 channel 도파로를 제작하였고 입사광의 제한 효과를 관찰하였다.

• Advances in materials Research
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• 제5권2호
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• pp.67-80
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• 2016

The objective of the present work is to optimize process parameters namely, cutting speed, feed rate, and depth of cut in milling of AISI 304 stainless steel. In this work, experiments were carried out as per the Taguchi experimental design and an $L_{27}$ orthogonal array was used to study the influence of various combinations of process parameters on surface roughness (Ra) and material removal rate (MRR). As a dynamic approach, the multiple response optimization was carried out using grey relational analysis (GRA) and desirability function analysis (DFA) for simultaneous evaluation. These two methods are considered in optimization, as both are multiple criteria evaluation and not much complicated. The optimum process parameters found to be cutting speed at 63 m/min, feed rate at 600 mm/min, and depth of cut at 0.8 mm. Analysis of variance (ANOVA) was employed to classify the significant parameters affecting the responses. The results indicate that depth of cut is the most significant parameter affecting multiple response characteristics of GFRP composites followed by feed rate and cutting speed. The experimental results for the optimal setting show that there is considerable improvement in the process.

• 한국농공학회논문집
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• 제52권6호
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• pp.9-17
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• 2010

In this paper, an automatic cruise system of unmanned boat was developed for surveying water depth in reservoir using GIS (geographic information system)-GPS (global positioning system) Technologies. the automatic cruise system consisted of an automatic path generation program (APGP) and an automatic boat control program (ABCP). A grid processing method with $3{\times}3$ roving window in GIS function was used to develop the APGP. For development of the ABCP, GPS and its coordinate calculation technique were introduced. The developed system was tested to verify the applicability for a sample reservoir, Misan reservoir located on Ansan city of Kyunggi province. From the test results, this study found the APGP generated cruise path automatically according to input condition on grid size of 5 m, 10 m, and 20 m, as well as, the ABCP also tracked well the cruise paths with high position accuracy. Another verification result on surveying time for 20 ha of water area also showed that the new system could survey water depth of reservoir quickly, including very high quality of spatial resolution.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 전기설비
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• pp.27-28
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• 2006

This paper deals with an approach to the reduction of potential rise according to the buried depth of structure. In order to analyze the surface potential rise of structure, an electrolytic tank which simulates the semi-infinite earth has been used. The potential rise has been measured and analyzed for types of structure using an electrolytic tank experimental apparatus in real time. The structure models were designed through reducing real buildings and fabricated with two types on a scale of one-one hundred sixty When a test current flowed through structure models, the potential rise of outline frame type(structure model A) was more high than that of electric cage type(structure model B). The distributions of surface potential rise are dependent on the buried depth of structure model.