• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.30-32
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• 2001

Switched reluctance motors have the advantage a high torque/weight ratio, as the large reluctance torque is made by salient poles of both start and rotor, and a high reliability. On the other hand, the switched reluctance motors have the disadvantage of a large ripple torque which is made by salient poles. So the application for the industrial fields have been limited to special cases. Geometric significant parameters are ${\beta}_r$ and ${\beta}_s$ respectively the rotor and stator pole arc while the significant electric parameters are the angles where the drive switches are turned on and off. It can be simulated that ${\beta}_r$ and ${\beta}_s$ must be chosen in a particular region of the plane (${\beta}_r,\;{\beta}_s$) called the feasible triangle. The aim of this paper is to simulate the minimum of the torque ripple by using finite element method and to determine the best choice of the rotor and stator pole arc.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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• pp.309-312
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• 2007

액체 로켓의 추진제로 이용되는 극저온 유체는 발사체의 경량화를 위한 터보 펌프의 고속화로 인해 공동현상이 발생하게 된다. 그러나 극저온 유체는 등온 유체인 물과는 달리 낮은 액상/증기 밀도 비율을 가지며 온도에 민감한 잠열변화율을 갖게 된다. 이에 따라 극저온 유체에서 공동 현상이 발생하게 되면, 증발 냉각 현상이 발생하게 되어 공동 내부와 주 유체 사이의 온도 차이가 발생하게 된다. 따라서 이러한 극저온 유체의 특징을 반영해 주기 위해 기존의 경험적 공동 현상 모델을 수정하여 새로운 모델을 적용하였다. 또한 온도 변화에 따른 효과를 반영해 주기 에너지 방정식을 첨가 하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.183-188
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• 2002

In locations where the cost or concrete is relatively high, or in situations where the weight or concrete members is to be kept to a minimum, it may be economical to use hollow reinforced concrete vertical members. Hollow reinforced concrete columns with low axial load, moderate longitudinal steel percentage, and a reasonably thick wall were found to perform in a ductile manner at the flexural strength, similar to solid columns. However, hollow reinforced concrete columns with high axial load, high longitudinal steel percentage, and a thin wall were found to behave in a brittle manner at the flexural strength, since the neutral axis is forced to occur away from the inside face of the tube towards the section centroid and, as a result, crushing of concrete occurs near the unconfined inside face of the section. If, however, a steel tube is placed near the inside face of a circular hollow column, the column can be expected not to fail in a brittle manner by disintegration of the concrete in the compression zone. Design recommendation and example by moment-curvature analysis program for curvature ductility are presented. Theoretical moment-curvature analysis for reinforced concrete columns, indicating the available flexural strength and ductility, can be conducted providing the stress-strain relation for the concrete and steel are known. In this paper, a unified stress-stain model for confined concrete by Mander is developed for members with circular sections.

• 대한전자공학회논문지TE
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• 제37권1호
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• pp.89-98
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• 2000

본 논문은 포워드 컨버터에 사용한 플레너 자기 소자의 설계 방법과 동작 특성에 관해 연구하였다. 플레너 자기 소자는 고주파 SMPS 설계시 발생할 수 있는 문제점에 대한 좋은 해결책이 될 수 있다. 이러한 플레너 자기 소자는 낮은 누설 리액터스, 낮은 구조, 경량 및 EMI 영향을 최소화 할 수 있는 등 여러 가지 좋은 장점들을 가지고 있어 최근 그 사용이 증대되고 있다. 본 논문에서는 플레너 자기소자를 이용한 포워드 컨버터를 제작한 후, 실험을 통하여 기존의 변압기를 사용한 경우와 비교하여 그 성능의 우수성을 입증하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.251-253
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• 2010

산화제 개폐밸브 개발 과정의 시험에서 금속 코니컬 씰이 장착된 밸브 중간 플랜지부에서 외부 누설이 발생하였다. 이에 기밀과 관련된 형상 변수인 볼트 수 및 플랜지 형상이 변경된 3가지 모델에 대하여 구조 해석을 수행하여, 설계 변경에 따른 무게 증가를 줄이고 동시에 플랜지간 벌어짐 양이 가장 적은 모델을 개선 모델로 선정하였다. 선정된 모델의 플랜지 부를 모사하는 시험 치구를 제작하여 기밀시험을 재수행하여 누설이 발생하지 않는 것은 확인하였으며, 결과적으로 플랜지 부의 기밀을 확보할 수 있는 설계 해석 방법을 검증하였다.

• 대한산업공학회지
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• 제39권6호
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• pp.554-561
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• 2013

As a special topic of the vehicle routing problems (VRP), VRPSDP extends the vehicle routing problem as considering simultaneous pickup and delivery for goods. The past studies have mainly dealt with a only weight constraint of a loading capacity for heterogeneous products. However. this study suggests VRPSDP considering separate loading area according to characteristics of loading species. The objective is to design a set of minimum distance routes for the vehicle routing assignment with independent capacity for heterogeneous species. And then we present a another HVRPSDP model which is easy to utilizes in a unique circumstance that is a guarantee of executing a task simultaneously from the various areas under restricted time and raising an application of vehicles that returns at the depot for the next mission like the military group. The optimal results of the suggested mathematical models are solved by the ILOG CPLEX software ver. 12.4 that is provided by IBM company.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.385-390
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• 2005

LMTT(Linear Motor-based Transfer Technology)는 항만 자동화를 위한 수평 이송 시스템이며, 셔틀카(shuttle car)와 격자구조의 레일에 부착된 스테이터 모듈(stator module)로 구성된 PLMSL(Permanent Magnetic Linear Synchronous Motor)에 의해 구동된다. 본 논문에서는 LMTT시스템 부품인 이동체(mover)의 경량화를 위하여 직교배열표 및 크리깅 방법을 이용하여 최적설계를 수행한다. 설계변수로는 가로빔, 세로빔, 휠빔의 두께와 높이 방향의 치수를 결정하는 형상변수를 포함시켰다. 목적함수로는 중량, 제한조건 함수로는 안전율이 고려된 응력으로 설정하였다. 본 연구에서 제시된 방법으로 구한 최적해를 민감도기반 최적설계로 구해진 최적해와 비교, 검토하였다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.62-67
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• 2004

Many ships in voyage experience weight and buoyancy distribution change by various reasons such as change of sea water density and waves, weather condition, and consumption of fuel, provisions, etc . The weight and buoyancy distribution change can bring the ships out of allowable trim, heeling angle. In these case, the ships should adjust trim and heeling angle by shifting of liquid cargo or ballasting, deballasting of ballast tanks for recovery of initial state or for a stable voyage. But, if the adjustment is performed incorrectly, ship's safety such as longitudinal strength, intact stability, propeller immersion, wide visibility, minimum forward draft cannot be secured correctly. So it is required that the adjustment of trim and heeling angle should be planned not by human operators but by optimization computer algorithm. To make an optimized plan to adjust trim and heeling angle guaranteeing the ship's safety and quickness of process, Uk! combined mechanical analysis and optimization algorithm. The candidate algorithms for the study were heuristic algorithm, meta-heuristic algorithm and uninformed searching algorithm. These are widely used in various kinds of optimization problems. Among them, heuristic algorithm $A^\ast$ was chosen for its optimality. The $A^\ast$ algorithm is then applied for the study. Three core elements of $A^\ast$ Algorithm consists of node, operator, evaluation function were modified and redefined. And we analyzed the $A^\ast$ algorithm by considering cooperation with loading instrument installed in most ships. Finally, the algorithm has been applied to tanker ship's various conditions such as Normal Ballast Condition, Homo Design Condition, Alternate Loading Condition, Also the test results are compared and discussed to confirm the efficiency and the usefulness of the methodology developed the system.

• 식품보건융합연구
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• 제5권3호
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• pp.1-5
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• 2019

The field experiment was conducted in vegetable area, Institute of Horticultural Sciences in University of Agriculture, Faisalabad in order to recognize morphological and fruit growth pattern and yield of Tinda (Praecitrullus fistulosus) gourd germplasm lines. Sixteen germplasm lines in which one line is used as check are included were sown and grown on flat beds in field. The field experiment was arranged as randomized complete block design (RCBD) with three replications. Data on days to maturity, fruit per vine, fruit weight in grams, fruit diameter and total yield obtained were recorded. The fruit texture is marked as phenotype parameter. All parameters were collected and then analyzed statistically. All lines and replications showed different results among each other according to parameter. The maximum DTM (days to maturity), F/P (fruit per plant), FW (fruit weight), FD (fruit diameter) and Yield were recorded was $L_0$ (68.66), $L_3$ (1.66), $L_{10}$ (248.33), $L_{13}$ (8.50) and $L_0$ (599.33) and the minimum were recorded was $L_1$ (56), $L_{11}$ (0.33), $L_0$ (198), $L_9$ (7) and $L_4$ (421) grams respectively. All lines showed smooth texture of fruits with no hairs when mature at harvesting stage.

• Asian-Australasian Journal of Animal Sciences
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• 제10권5호
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• pp.460-470
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• 1997

On an absolute straw diet, the effect of graded levels of green grass supplementation on intake, nutrient digestibility, rumen fermentation pattern and microbial N yield has been studied in cattle. Of the two trials conducted, 16 intact growing bulls of 304 kg weight and 32 months old, randomly allocated to four treatments in a completely randomized design in the 1st trial. While, in the, 2nd trial, four rumen cannulated local bulls of about 60 months old and 400 kg weight were used in a $4{\times}4$ Latin square design with four treatments in four periods. In both the trials, in addition to a mineral mixture, animals were supplemented with graded levels of naturally grown green grass of 0 kg (T1), 2 kg (T2), 4 kg (T3) or 6 kg (T4) to an ad libitum rice straw diet In the 1st trial, measurements were made on intake digestibility, growth rate, N balance and microbial N yield. While in the 2nd trial, in addition to the above parameters (except growth rate), rumen parameters were also studied. All levels of grass supplementation decreased the straw DM intake and increased the substitution rate. The rumen $NH_3-N$ concentration increased with the increase in grass level and ranges from 8-46 mg/l. The rumen pH and the rate and extent of DM degradability of straw were not affeceted by different rumen environments created by different levels of grass inclusion. At 48 h, straw DM degradability were 42, 44, 44 and 43% respectively for 0, 2, 4 and 6 kg grass supplementation daily. The whole gut digestibilities of DM, OM and ADF increased significantly (p < 0.05) only at 6 kg level daily. The microbial N yield was not affected by the levels of grass supplemented. The mean microbial N yield was 10 (SD 3.7) g/kg DOM apparently fermented in the rumen. The estimated minimum N loss and thus the maintenance requirement of tissue protein was 303 mg/kg $W^{0.75}/d$. All the animals lost live weight but 6 kg grass supplementation gave positive energy and N balances. Small amount of green grass supplementation is often recommended for optimization of rumen environment of a straw diet However, under the present experimental condition, no such beneficiary effect observed up to 6 kg (26% of DM intake) level of supplementation.