• 한국추진공학회지
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• 제17권1호
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• pp.26-34
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• 2013

사운딩로켓의 고도 극대화를 위한 최적의 분사조건을 결정하기 위한 해석적 접근법을 구축하기 위한 연구를 수행하였다. 로켓의 추력, 중력 및 공력저항을 고려한 1차원 모멘텀 방정식의 거동을 조사하였다. 해석적 해가 존재하는 경우에 대해, 분사 종료 단계에서의 최고 높이를 구할 수 있는 특성 방정식과 최고정점에 도달했을 때의 최고 높이를 구할 수 있는 특성방정식을 구하였으며, 이를 수치적 해와 비교하여 타당성을 검증하였다.

• 대한기계학회논문집B
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• 제28권12호
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• pp.1582-1590
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• 2004

The purpose of this study is to show the existence of optimal operation conditions for minimum fuel consumption of the gas turbine based combined cycle cogeneration power plant. Optimal operational condition means the optimal distribution of the power generated by each gas turbine and the heat generated by each HRSG. Total fuel consumption is calculated by the sum of the fuels for gas turbines and supplementary boiler. Fuel consumption is calculated by numerical methods of energy equations which contain the power generated from gas and steam turbines, the heat generated by HRSG and the heat extracted from high pressure steam turbine.

• 오토저널
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• 제14권6호
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• pp.113-126
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• 1992

Recently the multi-kind, small-amount manufacturing system has been replacing the mass manufacturing system, and domestic machining inustry also is eager to absorb the new technology because of its high productivity and cost reduction. The optimization of the cutting condition has been a vital problem in the machining industry, which would help increase the productivity and raise the international competitiveness. It is intended in this study to investigate the machining costs per unit time which is essential to the analysis of the optimal cutting condition, to computer the cutting speed that lead to the minimum machining costs and the maximum production to suggest the cutting speed range that enables efficient speed cutting, and to review the machining economy in relation to cutting depth and feed. Also considered are the optimal cutting speed and prodution rated in rrelation with feed. It is found that the minimum-cost cutting speed increases and the efficient cutting speed range is reduced as machining cost per unit time increases since the cutting speed for maximum production remains almost constant. The machining cost is also lowered and the production rate increases as the feed increases, and the feed should be selected to satisfy the required surface roughness. The machining cost and production rate are hardly affected by the cutting depth if the cutting speed stays below 100m/min, however, they are subject to change at larger cutting depth and the high-efficient speed range also is restricted. It can be established an adaptive optimal cutting conditions can be established in workshop by the auto-selection progam for optimal operation. It is expected that this method for choosing the optimal cutting conditions might contribute to the improvement of the productivity and reduced the cost. It is highly recommended to prepare the optimal cutting conditionthus obtained for future use in the programing of G-function of CNC machines. If proper programs that automatically select the optimal cutting conditions should be developed, it would be helpful to the works being done in the machine shops and would result in noticeable production raise and cost reduction.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.33-38
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• 2022

This study investigates the outlet temperature of coolant heater based on heat and flow volume conditions. Through computer simulation, the coolant temperature at the outlet was analyzed to investigate the heat and flow volume conditions of the coolant heater, and the optimal conditions were derived. Results show that heat and flow volume conditions, it was confirmed that heat condition is 0.424 W/mm³, and flow volume condition is 500 l/h, demonstrates optimal conditions. The results of this study can be utilized to efficiently control the coolant temperature through various heat and flow volume conditions.

• 한국기계가공학회지
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• 제16권5호
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• pp.105-112
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• 2017

In this study, plastics were deformed after molding due to the characteristics of the material. The Taguchi experimental design method was utilized to find the molding conditions that minimized deformation of the plastic bezel to be assembled in an automotive steering wheel. The injection molding conditions applied to the experimental design method are the melt temperature, cavity plate coolant temperature, core plate coolant temperature, and cooling time. Each condition was divided into five levels, and a total of 25 experiments were planned. However, instead of performing 25 actual molding experiments, the injection molding analysis was performed using the Moldflow program, and the deformation values for each molding analysis were obtained. The optimal molding conditions were obtained from these deformation values. The actual injection molding experiment using optimal molding conditions was compared with the deformation amount of the current molded product. The deformation was measured using a precise 3D scanner. The deformation amount of the molded product under optimal molding conditions was 16.1% lower than the deformation amount of the current molded product.

• Integrative Medicine Research
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• 제6권4호
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• pp.388-394
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• 2017

Background: The present study optimized ultrasound-assisted extraction conditions to maximize extraction yields of glycyrrhizic acid from licorice. Methods: The optimal extraction temperature ($X_1$), extraction time ($X_2$), and methanol concentration ($X_3$) were identified using response surface methodology (RSM). A central composite design (CCD) was used for experimental design and analysis of the results to obtain the optimal processing parameters. Results: Statistical analyses revealed that three variables and the quadratic of $X_1$, $X_2$, and $X_3$ had significant effects on the yields and were followed by significant interaction effects between the variables of $X_2$ and $X_3$ (p<0.01). A 3D response surface plot and contour plots derived from the mathematical models were applied to determine the optimal conditions. The optimum ultrasound-assisted extraction conditions were as follows: extraction temperature, $69^{\circ}C$; extraction time, 34?min; and methanol concentration, 57%. Under these conditions, the experimental yield of glycyrrhizic acid was 3.414%, which agreed closely with the predicted value (3.406%). Conclusion: The experimental values agreed with those predicted by RSM models, thus indicating the suitability of the model employed and the success of RSM in optimizing the extraction conditions.

• 한국기계가공학회지
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• 제21권2호
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• pp.123-129
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• 2022

Quartz (SiO2) has high abrasion and heat resistances and excellent chemical and mechanical properties; therefore, it is used in various industries, such as machinery, chemistry, optics, and medicine. Quartz is a high-hardness and brittle material and is classified as the topmost difficult-to-cut material, which is because of the cracking or chipping at the edge during processing. Corner wear, such as cracks and chippings that occur during cutting, is a major cause for the deterioration in the machining quality. Therefore, many researchers are investigating various techniques to process quartz effectively. However, owing to the mechanical properties of quartz, most studies have been conducted on grinding, micromachining, and microdrilling. Few studies have been conducted on quartz processing. The purpose of this study was to analyze the machining characteristics according to the machining factors during the slot machining of quartz using a cubic boron nitride (CBN) tool and to select the optimal machining conditions using the Taguchi method. The machining experiment was performed considering three process variables: the spindle speed, feed rate, and depth of cut. The cutting force and surface roughness were analyzed according to the processing conditions.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.61-61
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• 2022

For high quality bread wheat production in Korea, it is necessary to develop optimal nitrogen (N) fertilizer methods. For optimal N fertilizer, we evaluated the alteration of growth, yield, yield components and end-use qualities according to the treatment of N fertilizer amounts and timings at heading stages. Growth, yield, yield components, and end-use quality weren't altered by various timings of N fertilizer treatment conditions whereas, 1,000 grain weight and lodging degree was increased by increasing amounts of N fertilizer treatment conditions at 7 days after heading (7 DAH). Especially, lodging degree was significantly increased by 6kg/10a of N fertilizer treatment conditions at 7 DAH. The flour protein contents increased by various amounts of N fertilizer treatment conditions. However, SDS-sedimentation and bread loaf volumes were decreased by exceeding 6kg/10a of N fertilizer treatment conditions at 7 DAH. When considering the quality of bread, 6kg/10a N fertilizer treatment is best, but 3kg/10a N fertilizer treatment is more suitable for both quality and lodging at 7 DAH. Therefore, it is preferable to fertilize 3kg/10a of nitrogen at 7 DAH in addition to standard fertilizer when cultivate bread wheat.

• Food Science and Biotechnology
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• 제17권1호
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• pp.208-211
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• 2008

Previously, it has been reported that Aspergillus oryzae can efficiently degrade unpleasant odor components such as butyric acid and 3-methyl butanoic acid from meju, a major ingredient in both Korean soybean paste (doenjang) and soy sauce. In this study, the optimal manufacturing conditions for the production of superior quality Korean soybean paste and soy sauce were determined. Specifically, A. oryzae AJ 100 was utilized to improve the flavor of these products. Mixtures of Korean soybean paste and A. oryzae AJ 100 culture (2 : 1), and of Korean soy sauce and A. oryzae AJ 100 culture (5 : 1), were incubated for 2 weeks at $30^{\circ}C$, and showed improved flavor. Butyric acid and 3-methyl butanoic acid were clearly degraded under these culture conditions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.69-72
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• 1996

This paper considers a global resolution of kinematic redundancy under inequality constraints as a constrained optimal control. In this formulation, joint limits and obstacles are regarded as state variable inequality constraints, and joint velocity limits as control variable inequality constraints. Necessary and sufficient conditions are derived by using Pontryagin's minimum principle and penalty function method. These conditions leads to a two-point boundary-value problem (TPBVP) with natural, periodic and inequality boundary conditions. In order to solve the TPBVP and to find a global minimum, a numerical algorithm, named two-stage algorithm, is presented. Given initial joint pose, the first stage finds the optimal joint trajectory and its corresponding minimum performance cost. The second stage searches for the optimal initial joint pose with globally minimum cost in the self-motion manifold. The effectiveness of the proposed algorithm is demonstrated through a simulation with a 3-dof planar redundant manipulator.