• 제어로봇시스템학회논문지
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• 제10권6호
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• pp.537-544
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• 2004

An effective methodology is reported for determining the optimal lot size of batch processing and storage networks which include uncertain demand forecasting. We assume that any given storage unit can store one material type which can be purchased from suppliers, internally produced, infernally consumed, transported to or from other sites and/or sold to customers. We further assume that a storage unit is connected to all processing and transportation stages that consume/produce or move the material to which that storage unit is dedicated. Each processing stage transforms a set of feedstock materials or intermediates into a set of products with constant conversion factors. A batch transportation process can transfer one material or multiple materials at once between sites. The objective for optimization is to minimize the probability averaged total cost composed of raw material procurement, processing setup, transportation setup and inventory holding costs as well as the capital costs of processing stages and storage units. A novel production and inventory analysis formulation, the PSW(Periodic Square Wave) model, provides useful expressions for the upper/lower bounds and average level of the storage inventory. The expressions for the Kuhn-Tucker conditions of the optimization problem can be reduced to two sub-problems. The first yields analytical solutions for determining lot sires while the second is a separable concave minimization network flow subproblem whose solution yields the average material flow rates through the networks for the given demand forecast scenario. The result of this study will contribute to the optimal design and operation of the global supply chain.

• 수산해양기술연구
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• 제51권4호
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• pp.600-613
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• 2015

The Fishing gear loss has been repeated every year in the West Sea; however, there has been no solution. So fisher men have undergone economic loss every year. Thus it is required to reduce the loss of fishing gear. In this study to find out the reason that the fishing gear is lost in the Sea, 10 years data of wave and current for 6 locations in the West Sea were investigated and a numerical modelling were conducted into the behaviour of a gillnet in wave and current. The fishing gear was modelled with the mass spring model. As a result, it came out into the open that the location where fishing gear loss occurred most frequently was Choongnam province. The height of the maximum significant wave in this province was 6.7 m and the period of that was 4.4 second. The maximum current speed was 0.7 m/s. As a result of simulation with these data, it was revealed that the buoy is one of the reasons to decrease the holding power of the gillnet. For example, the tension of anchor rope was decreased to 50% while the drag coefficient or volume of buoy was decreased to 25%. So it is predicted that an improvement of the buoy contributes to the reduction of the gillnet loss.

• 대한기계학회논문집
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• 제17권1호
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• pp.51-61
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• 1993

본 연구에서는 에너지법으로 축대칭 박판성형 공정을 해석할 때, Lee와 Yang 이 제안한 방법을 적용함에 있어 굽힘효과를 효과적으로 고려할 수 있는 방법을 제안 하고 축대칭 컵드로잉 공정을 해석하여 본 이론의 타당성을 입증하고자 한다. 굽힘 효과는 박판소재를 몇개의 층(layer)으로 나눈 뒤, 각 층에서 소비되는 변형에너지를 합하여 전체 에너지를 최소화시킴으로써 고려하였다. 해석시 펀치 목부분과 다이목 부분에서의 접촉압력은 각각 균일한 분포를 갖는 것으로 가정하였다. 본 이론의 타 당성을 입증하기 위하여 계산결과를 실험치 및 탄소성 유한요소해석 결과와 비교하였 다.

• 한국임상수의학회지
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• 제15권2호
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• pp.472-475
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• 1998

A female Green iguana (Iguana iguana) was brought to the small animal clinic in Hannover Veterinary school because of anorexia and convulsion. Two months ago, the owner bought two iguanas, one female and one male and had to take a female to the one of local small animal clinic because she, born in 19931 didn't eat well and showed the tremor of the legs. The veterinarian suspected it to have a calcium deficiency and gave an injection of calcium and vitamin D3. But still during the last two months, the female iguana did only eat some lettuce while the other male ate lettuce, fruits and commercial cat-food ($Whiskas^{\circledR}$, Effem, Verden). It was not possible to evaluate the rations of these different "food-components". They are kept in the terrarium with water container. By palpation of the abdomen, hard thing like stone was palpated in the mid-region. The blood test wasn't carried out because of the difficulties of getting blood and because of her bad condition. It was firmly diagnosed as cystic calculus through radiography. Since the animal is in shock state already, the prognosis after surgery was bad. It was assumed to be too late to expect its surviving with the surgery carried out or without it. Cystotomy was performed in the cranial ventral paramedian incision in order to preserve the large ventral abdominal vein in the linen alba region. After two stay sutures ("holding suture" ) with 5-0 polyglactin 910 ($Vicryl^{\circledR}, Ethicon$) on the bladder, cystotomy was carried out and the stone inside was removed. Then, the bladder was closed in one-layer sutures. The abdomen was closed in simple interrupted suture with same material after the instillation of 10 ml saline solution into the abdominal cavity. The cystic calculus was in a size of $5.8{\times} 5.O{\times} 3.5 cm$. The analysis of the stone was carried out in two ways which are the infrared spectroscopy of the stone and quick analysis by $Merckognost^{\circledR}$(Diagnostica Merck, Merck). In the result of the infrared spectroscopy, the stone wee composed of 10% ammonium urate and 90% dihydrated uric acid. This iguana wasn't able to survive.n't able to survive.

• 한국재료학회지
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• 제27권3호
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• pp.132-136
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• 2017

We synthesized potassium hexatitanate, ($K_2Ti_6O_{13}$, PT6), with a non-fibrous shape, by acid leaching and subsequent thermal treatment of potassium tetratitanate ($K_2Ti_4O_9$, PT4), with layered crystal structure. By controlling nucleation and growth of PT4 crystals, we obtained splinter-type crystals of PT6 with increased width and reduced thickness. The optimal holding temperature for the layered PT4 was found to be ${\sim}920^{\circ}C$. The length and width of the PT4 crystals were increased when the nucleation and growth time were increased. After a proton exchange reaction using aqueous 0.3 M HCl solution, and subsequent heat treatment at $850^{\circ}C$, the PT4 crystal transformed into splinter-type PT6 crystals. The frictional characteristics of the friction materials show that as the particle size of PT6 increases, the coefficient of friction (COF) and wear amounts of both the friction materials and counter disc increase.

• 한국축산식품학회지
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• 제36권1호
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• pp.114-121
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• 2016

This study was performed to improve the techniques used for tenderizing red meat as elderly food. Beef meat was immersed in liposome encapsulated enzyme solution and the effect of protease encapsulation on the beef properties was analyzed. The protease encapsulation properties were analyzed according to the size distribution and enzymatic activity. After enzyme reaction on the beef, the chemical properties of the meat such as pH, water holding capacity, shear rate, lipid oxidation and total volatile basic nitrogen (TVB-N) were analyzed. The pH of the beef increased during the reaction and coating protease (CP) was higher than non-coating protease (NCP). Total color differences were increased remarkably after 36 h and generally, the difference in CP was relatively lower than in NCP. WHC was significantly decreased within 24 h, and no effect from the protease coating was observed. Protease activity was significantly increased within 48 h and no differences in the enzyme coating were observed. The TVB-N value of NCP was increased within 24 h while CP was sustained for up to 36 h. The TVB-N value of protease treated meat increased after 36 h and no effect from the protease coating was detected. Consequently, liposome encapsulated protease was found to have similar properties as non-coated protease. Application of liposome seems to be an interesting option for injecting various functional materials without changing the properties of meat.

• 한국식품과학회지
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• 제35권3호
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• pp.410-416
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• 2003

돈육에 칼슘 용액 주입 후 분자량 약 30 kDa의 키토산 1%와 젤라틴 3%의 혼합액을 코팅하여 $1^{\circ}C$에서 18일간 저장한 결과, 키토산/젤라틴을 코팅 처리한 전 실험구에서 저장성 및 지질의 산화도가 낮게 측정되었고, 적색도는 돈육의 내 외부에서 약간 증가하는 경향을 나타내었다. 키토산/젤라틴을 코팅한 돈육의 경우 저장기간 동안 수분함량 및 pH 변화에서도 안정하게 유지되었고, 보수력은 칼슘을 주입한 다음 키토산/젤라틴 혼합액으로 코팅한 돈육에서 비교적 높게 측정되었는데, 전반적으로 큰 차이를 보이지 않았다. 연도는 칼슘 용액을 돈육의 내부에 주입한 경우에 shear force가 가장 낮게 측정되었고, 이러한 결과는 근원섬유의 소편화도에서도 같은 결과를 나타내어 연도를 개선시키는데 효과적이었다. 따라서 돈육에 칼슘 용액을 주입하고, 키토산을 표면 처리하면 저장성의 증진 및 연도의 개선 등으로 돈육의 품질을 향상시키는데 적합한 방법이라 사료된다.

• 산업경영시스템학회지
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• 제35권3호
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• pp.77-86
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• 2012

We consider the capacitated lot-sizing and scheduling problem for a paper remanufacturing system that produces several types of corrugated cardboards. The problem is to determine the lot sizes as well as the sequence of lots for the objective of minimizing the sum of setup and inventory holding costs while satisfying the demand and the machine capacity over a given planning horizon. In particular, the paper remanufacturing system has sequence-dependent setup costs that depend on the type of product just completed and on the product to be processed. Also, the setup state at one period can be carried over to the next period. An integer programming model is presented to describe the problem. Due to the complexity of the problem, we modify the existing two-stage heuristics in which an initial solution is obtained and then it is improved using a multi-pass interchange method. To show the performances of the heuristics, computational experiments were done using the real data, and a significant amount of improvement is reported.

• 접착 및 계면
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• 제17권3호
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• pp.89-95
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• 2016

유연한 식품포장필름에 사용되고 있는 드라이 라미네이션용 유성접착제를 대체하기 위해, 고분자 분산제를 사용하여 유화하는 방법으로 수성 감압점착제를 친환경적으로 설계하였다. 유화중합에서 널리 사용하는 저분자량의 계면활성제는 물성의 변수로 작용해 왔다. 본 연구에서는 먼저 용액중합으로 polymeric nano-dispersant (PND)를 제조하고, 이 PND 입자들의 분산제를 micelle seed로 이용하여 core-shell grafted acrylic 점착제를 합성하였다. 이때 입자의 바깥층(shell)과 입자내층(core)의 $T_g$를 달리하여 얇은 필름의 점착조건인 초기접착력과 유지력의 균형을 이루도록 설계하였다. 최적화된 시험군 합성 점착제의 물성을 국내외 제조사에서 개발된 연구시료들과 비교분석하여, 점착제로서의 물성을 검토하였다. 물성 비교 결과, 본 연구에서 설계 합성한 저분자량의 계면활성제를 대체 사용한 고분자 나노분산제 기반 core-shell 점착제가 연포장에 적합한 점착물성을 나타냄을 확인하였다.

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