• 대한교통학회지
• /
• 제14권1호
• /
• pp.51-67
• /
• 1996

The optimal path-finding problem becomes complicated when multiple variables are simultaneously considered such as physical route length, degree of congestion, traffic capacity of intersections, number of intersections and lanes, and existence of free ways. Therefore, many researchers in various fields (management science, computer science, applied mathematics, production planning, satellite launching) attempted to solve the problem by ignoring many variables for problem simplification, by developing intelligent algorithms, or by developing high-speed hardware. In this research, an integration of expert system technique and case-based reasoning in high level with a conventional algorithms in lower level was attempted to develop an optimal path-finding system. Early application of experienced driver's knowledge and case data accumulated in case base drastically reduces number of possible combinations of optimal paths by generating promising alternatives and by eliminating non-profitable alternatives. Then, employment of a conventional optimization algorithm provides faster search mechanisms than other methods such as bidirectional algorithm and $A^*$ algorithm. The conclusion obtained from repeated laboratory experiments with real traffic data in Seoul metropolitan area shows that the integrated approach to finding optimal paths with consideration of various real world constraints provides reasonable solution in a faster way than others.

• 에너지공학
• /
• 제28권3호
• /
• pp.65-79
• /
• 2019

본 연구는 산업단지 내 Gas Combined Cycle CHP와 연계 가능한 신재생에너지원을 조합하여 최적의 설비용량을 산정하고자 하였다. 특히 2013~2016년도 에너지사용계획 협의 대상 산업단지 중 집단에너지 공급대상 지역지정 연료사용량 요건은 연간 3.8만 TOE로 미달되지만, 열밀도가 $92.6Gcal/km^2{\cdot}h$로 높은 세종첨단일반산업단지를 연구 대상으로 하였다. 그리고 신재생에너지 Hybrid System 경제성 분석 프로그램인 HOMER Pro를 이용하여 연료전지와 태양광발전을 연계한 FC-PV Hybrid CHP System의 최적화 운영 모델에 대해 분석하였다. 또 CHP의 주 공급 에너지원인 열에너지에 있어, 열수요량 뿐만 아니라 우점 업종에 대한 열수요 패턴을 분석하여 연구의 신뢰도를 높이고자 하였으며, 경제성 분석을 추가하여 상대적 편익을 비교하고자 하였다. 연구 결과, 신규 조성 중인 세종첨단일반산업단지의 전체 간접열 수요는 연간 378,282 Gcal이며, 이중 제지업종이 연간 293,754 Gcal인 약 77.7%를 우점하고 있었다. 산업단지 전체 간접열 수요에 대해 단일 Combined Cycle CHP의 최적 설비용량은 30,000 kW로, 이때 열생산은 CHP가 275,707 Gcal, 72.8 %를 분담하고, 첨두부하보일러 PLB가 103,240 Gcal, 27.2 %를 분담하는 것으로 분석되었다. 그리고 CHP와 연료전지, 태양광 조합에서는 최적 설비용량이 각 30,000 kW, 5,000 kW, 1,980 kW이며, 이때 열생산은 Combined Cycle CHP가 275,940 Gcal, 72.8%, 연료전지가 12,390 Gcal, 3.3%, PLB가 90,620 Gcal, 23.9%를 분담하였다. 여기서 CHP 용량이 감소하지 않은 것은, CHP 용량 감소에 따른 부족한 열 생산량에 대해 PLB의 과다한 운전이 요구되는 경제적이지 못한 대안이 도출되었기 때문이었다. 한편 우점 업종인 제지업종의 간접열 수요에 대해서는 Combined Cycle CHP, 연료전지, 태양광 조합의 최적 설비용량은 25,000 kW, 5,000 kW, 2,000 kW로, 이때 열생산은 CHP 225,053 Gcal, 76.5%, 연료전지 11,215 Gcal, 3.8%, PLB가 58,012 Gcal, 19.7%를 분담하는 것으로 분석되었다. 그러나, 현행 전력시장 및 가스시장에서의 경제성 분석결과는 모두 투자비 회수가 불가능한 것으로 확인 되었다. 다만, 우점 업종인 제지 업종만을 대상으로 CHP와 연료전지, 태양광을 조합한 CHP Hybrid System이 단일 CHP System에 대해 연간 약 93억원의 경영여건을 개선시킬 수 있음을 확인하였다.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제18권3호
• /
• pp.58-64
• /
• 2013

This study proposed a low temperature hydrothermal carbonization to treat and recycle sewage sludge and determined the optimal conditions for the biochar production. The physical and chemical properties of biochar were analyzed and its sorption capacity for heavy metals was evaluated. To produce biochar, 50 g of sewage sludge was heated at 220, 230, and $240^{\circ}C$ for 1, 2, 3, 5, 8, and 10 hours in a reactor. The optimal conditions to produce biochar was $230^{\circ}C$ and 8 hours. Sorption capacity tests were conducted for arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn) and nickel (Ni). Among them, lead was shown the highest heavy metal adsorption efficiency of biochar, followed by copper, cadmium, zinc, and nickel, but arsenic was hardly adsorbed overall.

• 대한산업공학회지
• /
• 제1권1호
• /
• pp.41-56
• /
• 1975

In the past the pattern of business down-trend usually appeared in the form of, first, decrease in facility investment, then decrease in inventory level, followed by reduced level of consumption. But the pattern nowadays is becoming just the opposite, that is, first, consumption decrease, then inventory level increase, followed by restriction of facility investment. Also in the past, the greater effort was placed in strengthening of hardware areas through optimization and modernization of production means on the premise of sales. But lately software areas take most of the main effort to establish production mean with sales as its objective. Under these circumstances one of the real problems facing production activities today is the conflicting relationship between sales and production functions. This occurs due to differences of their view points. Then, in order to achieve maximum profit at the least cost, which is the ultimate objective of a production activity, the need arises to effectively coordinate sales demand and plant production capacity. For this purpose strong control means and function must be devised. In our case study example we illustrate a management technique for a combined planning function, of optimal coordination of product mixes utilizing a computerized linear programming model as control means of attaining maximum profit. It is hoped that this example help achieve some of corporate objectives.

• 한국수소및신에너지학회논문집
• /
• 제33권5호
• /
• pp.534-540
• /
• 2022

Liquid hydrogen has the best storage capacity per unit mass and is economical among storage methods for using hydrogen as fuel. As the demand for hydrogen increases, the need to develop a storage and supply system of liquid hydrogen is emphasizing. In order to liquefy hydrogen, it is necessary to pre-cool it to a maximum inversion temperature of -253℃. The Gifford-McMahon (GM) refrigerator is the most reliable and commercialized refrigerator among small-capacity cryogenic refrigerators, which can extract high-efficiency hydrogen through liquefied hydrogen production and boil of gas re-liquefaction. Therefore, in this study, the optimal conditions for liquefying gas hydrogen were sought using the GM cryocooler. The process was simulated by PRO/II under various cooling capacities of the GM refrigerator. In addition, the flow rate of hydrogen was calculated by comparing with specific refrigerator capacity depending on the pressure and flow rate of a refrigerant medium, helium. Simulations were performed to investigate the optimal values of the liquefaction flow rate and compression pressure, which aim for the peak refrigeration effect. Based on this, a liquefaction system can be selected in consideration of the cycle configuration and the performance of the refrigerator.

• Journal of Nutrition and Health
• /
• 제27권8호
• /
• pp.794-804
• /
• 1994

This study was conducted to investigate the relationship between lactational capacity and intakes of energy and energy-yielding nutrients. Food consumption, intakes of carbohydrate, protein, fat and energy and quantity and proximate composition of milk of 11 lactating Korean mothers were determined at 1, 2 and 3 months postpartum longitudinally. Food consumption was estimated using a 24-hour recall method ; intakes of energy and energy-yielding nutrients were calculated according to the Food Composition Table. Daily milk production was estimated using a 72-hour test-weighing method ; protein, fat, lactose and energy concentrations were analyzed. Average intakes of energy and protein were 1974$\pm$386㎉/day and 67.0$\pm$12.3㎉/day, these were 73% and 74% of the Korean Recommended Allowances, respectively. Average milk yield was 720.1$\pm$123.3ml/day containing energy 59.6$\pm$9.5㎉/dl, protein 1.1$\pm$0.1g/dl, fat 2.7$\pm$0.8g/dl, and lactose 6.3$\pm$0.3g/dl. No relationship existed between the intakes of carbohydrate, protein, fat and energy and the quantity and proximate composition of the milk. However, the intakes of energy, carbohydrate and vegetable protein were inversely related to the concentrations of energy and lactose in the milk. This result indicates that lactational capacity may be affected by the other factors excluding intakes of energy and energy-yielding nutrients and a high intake of energy may not guarantee optimal lactational capacity.

• 제어로봇시스템학회논문지
• /
• 제16권3호
• /
• pp.305-312
• /
• 2010

The aim of this study is to find an analytic solution to the problem of determining the optimal capacity of a batch-storage network to meet demand for finished products in a system undergoing joint random variations of operating time and batch material loss. The superstructure of the plant considered here consists of a network of serially and/or parallel interlinked batch processes and storage units. The production processes transform a set of feedstock materials into another set of products with constant conversion factors. The final product demand flow is susceptible to joint random variations in the cycle time and batch size. The production processes have also joint random variations in cycle time and product quantity. The spoiled materials are treated through regeneration or waste disposal processes. The objective function of the optimization is minimizing the total cost, which is composed of setup and inventory holding costs as well as the capital costs of constructing processes and storage units. A novel production and inventory analysis the PSW (Periodic Square Wave) model, provides a judicious graphical method to find the upper and lower bounds of random flows. The advantage of this model is that it provides a set of simple analytic solutions while also maintaining a realistic description of the random material flows between processes and storage units; as a consequence of these analytic solutions, the computation burden is significantly reduced. The proposed method has the potential to rapidly provide very useful data on which to base investment decisions during the early plant design stage. It should be of particular use when these decisions must be made in a highly uncertain business environment.

• 산업경영시스템학회지
• /
• 제32권3호
• /
• pp.118-126
• /
• 2009

This research investigates the problem of minimizing setup costs in resequencing jobs having first-in, first-out(FIFO) constraints at conveyorized production or assembly systems. Sequence changing at conveyor junctions in these systems is limited due to FIFO restriction. We first define the general problem of resequencing jobs to workstations satisfying precedence relationships between jobs(Generalized Sequential Ordering Problem, GSOP). Then we limit our scope to FIFO precedence relationships which is the conveyor selection problem at a diverging junction(Diverging Sequential Ordering Problem, DSOP), modeling it as a 0-1 integer program. With the capacity constraint removed, we show that the problem can be modeled as an assignment problem. In addition, we proposed and evaluated the heuristic algorithm for the case where the capacity constraint cannot be removed. Finally, we discuss the case study which motivated this research and numerical results.

• Journal of Microbiology and Biotechnology
• /
• 제7권3호
• /
• pp.204-208
• /
• 1997

Aureobasidium puliulans possesses the capacity for simultaneous formation of fructosyltransferase and glucosyltransferase in various sugar media including sucrose, maltose, glucose and fructose. Among them, sucrose (300 g/1) was the most suitable carbon source for fructosyltransferase production, while fructose (100 g/1) gave the maximal production of glucosyltransferase. There existed a critical concentration for the optimal formation of enzymes in sucrose, glucose and fructose media. By contrast, no effect of maltose concentrations up to 300 g/1 was observed. The specific activity of the glucosyltransferase on maltose medium was highest during the early period of fetmentation, after which a sharp decrease occurred, whereas fructosyltransferase activity on sucrose medium maintained a nearly constant rate for a given culture period. Concomitant production of fructosyltransferase and glucosyltransferase was investigated with different combinations of lower concentrations of sucrose and maltose. Maltose supplementation in sucrose media and sucrose addition to maltose media enhanced the activity ratios of fructosyltransferase to glucosyltransferase as compared to that of non-supplemented media. Several polymers and surfactants were added in an attempt to enhance enzyme production, and supplementation of polyoxyethylene-sorbitan monolaurate (Tween 20) promoted fructosyltransferase production by 20%.

• Asian-Australasian Journal of Animal Sciences
• /
• 제23권2호
• /
• pp.279-286
• /
• 2010

Livestock production in Vietnam is, as in most Asian countries, increasing rapidly and changing into specialized highly intensified operations. The volume of animal excreta generated exceeds the capacity of the operation land base and cannot be utilized efficiently. As a consequence, there is a loss of plant nutrients from livestock farms that causes environmental pollution. This study carried out a feed and excretion experiment measuring fecal characteristic, daily fecal production, daily nitrogen and phosphorous excretion from grower-finisher pigs fed prevalent rations in Vietnam. Furthermore, equations for assessing the excretion were tested, which can be used in farm models for optimal recycling of manure while focusing on reducing pollution. The results indicated that fecal production and nutrient excretion were affected by the different rations tested. This study showed that five selected equations for predicting excretion from grower-finisher pigs in Danish conditions can also be used with precision in Vietnamese pig farming systems. The equations have been proven valid and can, therefore, be used as a much needed tool for assessing fecal production and nitrogen in excreta on pig farms. The study also showed that about 12% of nitrogen excreted was emitted during housing. Waste water contains more than half of the nitrogen excreted, mainly in ammonium form which has a high potential for gaseous emission.