• 한국국방경영분석학회지
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• 제24권1호
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• pp.157-175
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• 1998

This paper develops multiple objective manpower planning model in order to design and adjust manpower structure and flow when advance rate for officer's native is considered. The state transition in manpower structure is analyzed using Markov chains. Multiple objectives in the model are security of advance rate, satisfaction of rank's number of personnel, and stability of the number of recruit personnel for officer's native. Trade - off of these objectives is made to evaluate manpower structure and flow. Solutions of this model are obtained by LINGO package.

• 에너지공학
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• 제24권4호
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• pp.217-222
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• 2015

A computer simulation has been developed to predict and investigate the performance of the assumed hydrogen engine. The simulation has be come a powerful tool as it saves time and also economical when compared to experimental study. The effects of various parameters, such as equivalent ratio, spark advance, revolutions per minute were calculated and then the optimal parameters of assumed engine were determined. The effects of spark advance, revolutions per minute, cylinder pressure, rate of pressure rise, flame temperature, rate of heat release, and mass fraction burned were simulated. The objective of the research paper is to develop a internal combustion model with hydrogen as a fuel.

• 한국농공학회논문집
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• 제46권4호
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• pp.3-11
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• 2004

A finite volume model is developed to simulate the surface irrigation at a paddy field. The model's capabilities are validated through comparison with the simulafed results and the observed data obtained by various experimental tests, and the simulated results are in good agreement with the observed pending depth. The result of surface irrigation simulation shows that the longer the paddy field's the length of long-sided becomes, the longer the advance and storage time is taken. To analyze surface irrigation performance with variable inflow rate, three patterns of flow variation-constant rate, initially high then low, and initially low then high-were studied. The results show that at the pattern with initially high followed by low during the latter half of the irrigation the advance time is shortest, but the pending depth of irrigation completion and irrigation effiency are the little difference between irrigation patterns.

• 터널과지하공간
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• 제17권3호
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• pp.225-233
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• 2007

노르웨이는 계곡이나 피요르드와 같은 굴곡이 심한 지형 때문에 터널이 많이 건설되었으며, 그 가운데 지난 30년 동안 59개의 터널이 전단면 기계굴착으로 완성되었다. 이러한 기계굴착 경험을 통하여 예측기법이 개발되고 발전되었으며 마침내 국립공과대학인 NTNU에서 예측법이 체계화되었다. 본 보고는 TBM 굴착자료가 알려진 14개의 노르웨이 터널과 4개의 국내의 터널에서 순굴착속도와 굴진속도를 분석하여, 이들의 발전경향을 연구한 것이다. 이 기간동안 노르웨이에서는 디스크 커터의 직경을 증대시키고 배열을 최적화하여 순굴착속도와 굴진속도를 두배 정도로 증진시켰다. 국내에서도 1980년부터 1990대까지 15년 동안 IBM의 굴진속도는 노르웨이에 비하여 작은 크기이지만 뚜렷이 증가하는 경향을 보였다. 이러한 작은 속도는 암반의 특성에도 기인하지만 17 인치보다 작은 직경의 디스크 커터를 사용한데 크게 기인된 것으로 판단된다. 향후 국내의 전단면 기계굴착에서 장비와 기술의 개선을 이루고, 특히 17 또는 19 인치의 디스크 커터를 사용한다면 순굴착속도와 굴진속도를 향상시킬 수 있을 것으로 예측된다.

• KEPCO Journal on Electric Power and Energy
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• 제6권3호
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• pp.305-313
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• 2020

전력송전을 위한 터널식 전력구는 점차 시공실적이 증가하고 있는 추세이며, 해저 및 대심도 등 시공환경이 어려운 구간의 건설도 증가하고 있다. 이에 소단면 쉴드TBM의 효율적 운영을 위해 굴진율 및 설계모델이 필요하다. 그러나, 제한된 지반조사 회수 및 굴착면 맵핑으로 인하여 암반특성과 굴진데이터를 정확히 매칭시켜 상호간 상관관계 및 굴진율 모델을 도출하는데 어려움이 있다. 이에 소단면 쉴드TBM에 적합한 굴진율 및 설계모델을 제시하기 위하여 커터헤드의 직경이 3.56 m인 실험용 EPB 쉴드TBM을 제작하고, 총 부피 87.5 ㎥인 인공암반 내에서 총 19번의 실대형 굴진실험을 수행하였다. 본 실험은 70MPa의 균질한 암반강도에서 수행되었기 때문에 운전변수인 추력과 커터헤드의 RPM에 따른 굴진율과 기계데이터간 상관관계를 효율적으로 분석할 수 있으며, 실제 굴착메커니즘과 동일하기 때문에 도출된 압입깊이와 토크값은 활용성이 높다. 본 연구를 통해 디스크커터 당 연직력과 압입깊이의 상관관계 및 연직력과 회전력의 상관관계를 도출하였다. 이러한 상관관계들을 이용하여 70 MPa급 암반에 대해 굴진율 예측과 TBM 설계가 가능할 것으로 판단한다. 또한, 인공암반의 RQD가 100%로 현장적용에 대한 한계점에 대해 FPI의 개념을 도입하여 굴진율 모델의 활용성을 증대시키고자 하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권6호
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• pp.655-667
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• 2017

The results of a numerical study on the performance of a propeller operating near a free surface are presented. The numerical simulations were performed for the various advance coefficients and the submergence depths of the model propeller. The effects of the model propeller size were investigated using two different model propeller sizes for all cases. The wave pattern of the free surface and the flow structure around the propeller as well as the hydrodynamic characteristics of the propeller were investigated through simulation results. The thrust and torque fluctuated and the trajectory of the tip vortex was distorted due to the interaction with the free surface. The wave pattern of the free surface was related to the tip vortex of the propeller. The decreases in thrust and torque at the small model propeller were greater than those of the large model propeller. The reduction rate of the thrust and torque increased with the advance coefficient.

• 대한토목학회논문집
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• 제31권6D호
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• pp.839-848
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• 2011

TBM(Tunnel Boring Machine) 터널은 굴진 도중 장비의 교체나 개조 등은 불가능하기 때문에 굴진 종료 시까지 투입된 장비로 굴진하여야만 한다. 특히 토압식 쉴드TBM은 막장관찰이 어려우므로 굴진 중에 수집된 자료를 분석하여 지반상태의 변화를 예측하고 이를 시공에 반영하여야한다. 지금까지의 TBM에 대한 연구는 굴착 대상이 되는 지반의 특성에 따른 장비선정 및 굴진속도 예측모델 개발이 주로 이루어져왔다. 그러나 굴착의 주체가 되는 TBM 장비의 굴진자료에 의한 지반상태의 추정 및 운전방법의 개선에 초점을 맞춘 연구는 그리 많이 수행되지 않았다. 본 연구는 토압식 쉴드TBM 시공 사례에서 얻은 굴진자료를 활용하여 투입된 장비의 운전조건에 따른 굴진속도의 변화와 최적 운전조건에 대해 알아보았다. 본 연구의 결과를 요약하면 다음과 같다. 첫째, 커터헤드의 회전속도와 총추력이 굴진속도에 가장 큰 영향을 주며 둘째, 적정한 굴진속도를 위해서는 최적 회전속도를 유지하면서 총추력을 조정하는 것이 좋으며 셋째, 총추력의 증가 추세에 따라 지반조건의 변화에 대한 예측이 가능하여 이에 따라 적절한 운전조건의 변경을 결정할 수 있다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.448-455
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• 2005

In this paper, an analytical model for estimation of the time at which the concrete surface begins to dry is introduced to predict whether or not plastic shrinkage cracks occur. First of all, the validity of a consolidation model for bleeding of cement paste proposed by Tan et al. is verified by comparing the analytical results with the experimental results, and used to evaluate the rate and amount of bleed water of concrete. Also an analytical model for evaporation of bleed water which considers the effect of the temperature variation of concrete surface due to hydration heat on the evaporation rate is proposed, and the experimental and analytical results are then compared to verify the validity of the introduced model. In advance, the time at which the concrete surface begins to dry is estimated using above two analytical models, and compared with the experimental results about the time at which plastic shrinkage cracks occur. From the comparison, it is verified that the proposed model can predict the occurrence of plastic shrinkage cracking with comparative precision.

• 디지털산업정보학회논문지
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• 제19권4호
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• pp.137-146
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• 2023

The dropout of university freshmen is a very important issue in the financial problems of universities. Moreover, the dropout rate is one of the important indicators among the external evaluation items of universities. Therefore, universities need to predict dropout students in advance and apply various dropout prevention programs targeting them. This paper proposes a method to predict such dropout students in advance. This paper is about a method for predicting dropout students. It proposes a method to select dropouts by applying logistic regression using a shift sigmoid classification function using only quantitative data from the first semester of the first year, which most universities have. It is based on logistic regression and can select the number of prediction subjects and prediction accuracy by using the shift sigmoid function as an classification function. As a result of the experiment, when the proposed algorithm was applied, the number of predicted dropout subjects varied from 100% to 20% compared to the actual number of dropout subjects, and it was found to have a prediction accuracy of 75% to 98%.

• 조명전기설비학회논문지
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• 제25권12호
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• pp.11-20
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• 2011

PSALI is referred to the supplementary lighting for the interior lighting under the daily lighting situation, and pursuant to the pertinent regulations in energy savings design standard and others in recent architecture works, the importance thereof has been increasing gradually coupled with the energy performance index (EPI), energy savings plan and the like as well as expansion of submittal and implementation policies. However, this type of PSALI studies indeed have a number of limitations since it has surrounding environmental conditions in direction, season, region, climate, time, opening rate, window area ratio, actual index, reflection rate of finishing materials and others in the architecture work as well as frequent changes in interior lighting environment for variables in daily light volume flowing into the interior, and others. Therefore, this study has analyzed existing advance research cases to produce the actual-sized model and scaled-down model, and installed the artificial lighting of LED light source possible to reproduce with same capability on both models. As a result of comparison and analysis of the artificial lighting with the key light, it has certain level of error rate from the scaled down lighting device in certain rate and actual model butit was noticeably significant within specific scope.