• 한국시뮬레이션학회논문지
• /
• 제25권2호
• /
• pp.75-81
• /
• 2016

고정위치 생산 방식과 이를 개선한 흐름 생산 방식의 생산성을 비교하기 위해 데크하우스 선행의장 공정의 사례를 이용하여 이를 비교 분석하였다. 현재의 선행의장 공정 시스템은 고정위치 생산을 하고 있으며, 여기서는 블록이 한 구역을 점유하고, 작업이 완료 될 때까지 이동하지 않는다. 반면 개선된 흐름생산시스템에서는 블록이 이동하며 작업자와 장비는 움직이지 않는다. 시뮬레이션 결과 제안된 생산시스템에서 블록의 이동시간과 대기시간을 고려하지 않았을 때는 블록의 생산량이 거의 증가하지 않았다. 그러나 흐름생산에서는 작업을 위한 장비와 작업자의 이동과 대기시간이 거의 없어, 작업장의 작업시간의 변동성을 줄일 수 있다면 흐름생산이 고정위치 생산 시스템을 대체하는 보다 더 우수한 대안이 될 수 있음을 보였다.

• 대한산업공학회지
• /
• 제10권1호
• /
• pp.11-16
• /
• 1984

An economic model is developed for determining optimal locations of screening inspection stations in a multistage production system. The effect of screening inspection on the production rate is explicitly considered, and a fixed cost for maintaining an inspection station is assumed. The product is allowed to have multiple defects, each of which may be inspected at any inspection station after the defect-generating operation. The problem is formulated as a mixed 0-1 linear program which offers the advantage of versatility in handling various system constraints.

• Nuclear Engineering and Technology
• /
• 제55권4호
• /
• pp.1225-1232
• /
• 2023

The ¹⁸⁰W is the lightest isotope of Tungsten with small abundance ratio. It is slightly radioactive (α decay), with an extremely long half-life. Its separation is possible by non-conventional single withdrawal cascades. The ¹⁸⁰W is used in radioisotopes production and study of metals through gamma-ray spectroscopy. In this paper, single withdrawal cascade model is developed to evaluate multicomponent separation in non-conventional transient cascades, and available experimental results are used for validation. Numerical studies for separation of ¹⁸⁰W in a transient single withdrawal cascade are performed. Parameters affecting the separation and equilibrium time of cascade such as number of stages, cascade arrangements, feed location and flow rate for a fixed number of gas centrifuges (GC) are investigated. The Salp Swarm Algorithm (SSA) as a bio-inspired optimization algorithm is applied as a novel method to minimize the feed consumption to obtain desired concentration in the collection tank. Examining different cascade arrangements, it is observed in arrangements with more stages, the separation is further efficient. Based on the obtained results, with increasing feed flow rate, for fixed product concentration, the cascade equilibrium time decreases. Also, it is shown while the feed location is the farthest stage from the collection tank, the separation and cascade equilibrium time are well-organized. Finally, using SSA optimal parameters of the cascade is calculated, and optimal arrangement to produce 5 gr of ¹⁸⁰W with 90% concentration in the tank, is proposed.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
• /
• pp.39-45
• /
• 2006

Analysis of the internal state of the blast furnace is needed to predict and control the operating condition. Especially, it is important to develop modeling of blast furnace for predicting cohesive zone because shape of cohesive zone influences overall operating condition of blast furnace such as gas flow, chemical reactions and temperature. because many previous blast furnace models assumed cohesive zone to be fixed, they can't evaluate change of cohesive zone shape by operation condition such as PCR, blast condition, and production rate. In this study, an axi-symmetric 2-dimensional steady state model is proposed to simulate blast furnace process. In this model, cohesive zone is changed by solid temperature range, FVM is used for numerical simulation. To find location of cohesive zone whole calculation procedure is iterated Until cohesive zone is converged. Through this approach, shape of cohesive zone, velocity, composition and temperature within the furnace are predicted by model.

• Asian-Australasian Journal of Animal Sciences
• /
• 제25권11호
• /
• pp.1634-1640
• /
• 2012

The objective of this study was to compare pork characteristics and to determine consumer acceptability of pork chops from antibiotic free Yorkshire crossbreds sired by Berkshire (BY), Large Black (LBY), Tamworth (TY) or Yorkshire (YY) boars and reared in hoop houses. The experiments were conducted at the North Carolina Agricultural and Technical State University (NCA&TSU) Farm in Greensboro, NC and the Cherry Research Station Center for Environmental Farming Systems (CEFS) Alternative Swine Unit in Goldsboro, NC (source of antibiotic free Yorkshire sows used at both places). Twenty-four sows were artificially inseminated at each location in each of three trials. Litters were weaned at 4 wks old, and reared within deep-bedded outdoor hoop houses. To compare pork characteristics, 104 randomly selected animals were harvested at a USDA-inspected abattoir at approximately 200 d of age. Variables measured included pH, color score, $L^*$, $a^*$, $b^*$, marbling score, drip loss, hot carcass weight, backfat thickness (BF), loin muscle area (LMA), and slice shear force. Sensory panel tests were also conducted at two time periods. The data was analyzed with GLM in SAS 9.01 including location, trial, and sire breed as fixed effects. Backfat thickness, LMA, color score and $a^*$ were different among breeding groups (p<0.05). The LBY pigs had thicker backfat and smaller LMA than the other breed types. The TY and YY had less backfat than all other breed groups. Color score was lower for YY than BY and LBY but intermediate for TY. The $a^*$ was lower for TY than other breeds except LBY which was intermediate. For one sensory panel test, YY pork was more preferred overall as well as for juiciness and texture compared to BY and LBY (p<0.05), but no impact of breed type was noted for the other test, with values similar for BY, LBY, TY and YY pork. This information may help small farmers make decisions about breed types to use for outdoor production.

• 자원ㆍ환경경제연구
• /
• 제15권4호
• /
• pp.761-782
• /
• 2006

미국의 농업경영, 특히 축산업으로 인한 잠재적인 환경피해는 많은 우려를 낳고 있다. 축산업간에도 종별로 생산과정과 축산폐수관리 과정 등이 다르고 특히 각기 다른 산업별 구조변화로 환경정책의 영향은 각각 다를 것이다. 비육우의 경우 전통적으로 강한 주들이 지금도 주요한 생산지이지만 양돈의 경우에는 규모별 입지가 급격히 변해왔고 이 과정에서 환경정책에 대한 반영이 비육우의 경우보다 더욱 능동적이었을 것으로 사료된다. 본 연구는 이 같은 가정 하에 양돈업이 축산규제로부터 더 강한 영향을 받을 뿐 아니라 더 많은 영향을 줄 것이라는 가설을 세웠다. 결과를 보면 주 정부의 집행의사가 없는 규제정책은 큰 효율성이 없는 것으로 나타났다. 반면 집행의지는 상당한 영향을 주는 것으로 분석되었다. 그러나 양돈업과 같이 내부적인 구조변화가 심하게 진행되고 있는 경우가 양돈업의 규모와 입지선정에 보다 민감함을 보였다. 환경순응비는 전체 생산비 중 극히 일부분에 불과하다. 따라서 육우산업의 경우에는 높은 고정비 때문에 환경순응에 상대적으로 덜 민감한 반면 양돈업의 경우에는 구조변화 과정에서 환경순응비를 고려한 위치와 규모를 민감하게 반영하고 있는 것으로 판단된다. 미국의 많은 주들이 양돈을 대상으로 한 새로운 규제를 시행하고 있는 점도 이를 시사하는 것이다.

• Applied Microscopy
• /
• 제3권1호
• /
• pp.29-38
• /
• 1973

Introduction. The human cutaneous scars manifest themselves many ways in different types according to the factors such as the age, sex, race of the patient as well as the location,. kind and heal ing process of the wound. Among the scars it is quiet difficult to verify the clinical course of the hypertrophic or keloidal scars from the true keloids. However, clinical observations indicate that stress, either mechanical or in the forms of chronic infections, can induce a functional change in the fibroblasts causing an excessive production of collagenous matrix. In this study, we preliminary attempt to justify any difference of the cellular structure between keloids and hypertrophic scars by using electron microscope. Material and Methods. A total of 23 cases: 2 scars, 2 hypertrophic scars and 19 keloids are examined. Immediately, the biopsy tissue was fixed in 10% neutral formalin and 4% glutaraldehyde solution in phosphate buffer for 4 hours, post fixed in 1 % osmium tetraoxide for two hours, dehydrated with graded alcohol, and embedded in Epon 812. Thick sections were stained with hematoxylin eosin, periodic acid-Schiff(PAS) and Van Gieson stain. Thin sections were cut and uranyle acetate, lead citratestain and examined with the electron microscope. Result. The morphologic features of keloid showed thick, homogenously eosinophilic bands of collagen and numberous large active fibroblasts. The hypertrophic scar and soft scar are more cellular than keloid and composed thinner collagenous fiber. For this paper in the etiology of keloids can not as be defined, but and interesting keloidal tissue fibroblast showed irregular nucleus with irregular shape dense bodies and fibril materials contained in to the cytoplasm.

• 대한기계학회논문집B
• /
• 제20권10호
• /
• pp.3262-3271
• /
• 1996

Flow patterns were measured in a shrouded centrifugal impeller. The flow rate in measurements was fixed at the value corresponding to a nearly zero incidence at the blade inlet. By using a single slanted hot-wire probe and a Kiel probe mounted on the impeller hub disk, the 3-D relative velocities and the rotary stagnation pressures were measured in seven circumferential planes from the inlet to the outlet of impeller rotating at 700 rpm, and the static pressure distribution along flow passage and the slip factor at impeller outlet were calculated from the measured values. From these measured data, the primary and secondary flows, the wake production and the static pressure rise in the impeller passage were investigated. Furthermore, the secondary flow patterns and the wake's location in this impeller passage were compared with those of the unshrouded impeller.

• 한국연소학회지
• /
• 제14권4호
• /
• pp.1-6
• /
• 2009

Analysis of the internal state of the blast furnace is necessary to predict and to control the operating conditions. Especially, it is important to develop models of the blast furnace to predict the cohesive zone because shape of the cohesive zone influences overall operating conditions of blast furnace such as gas flow, chemical reactions and temperature. Because many previous blast furnace models have assumed cohesive zone to be fixed, it was not possible to evaluate the shape change of cohesive zone in relation with operating conditions such as PCR, blast condition, and production rate. In this study, an axi-symmetric 2-dimensional steady state model is proposed to simulate blast furnace processes. In this model, cohesive zone is determined by the solid temperature. Finite volume method is employed for numerical simulation. To find location of the cohesive zone, entire calculation procedure is iterated until converged. Through this approach, shape of the cohesive zone, velocity and temperature within the furnace are predicted from the model.

• 전자공학회논문지B
• /
• 제32B권11호
• /
• pp.1393-1404
• /
• 1995

For the factory automation(FA) of production or assembly lines, computer vision techniques have been widely used for the recognition and position-control of objects. In this application, it is very important to analyze characteristic features of each object and to find an efficient matching algorithm using the selected features. If the object has regular or homogeneous patterns, the problem is relatively simple. However, If the object is shifted or rotated, and if the depth of the input visual system is not fixed, the problem becomes very complicated. Also, in order to understand and recognize objects with concentric noise patterns, it is more effective to use feature-information represented in polar coordinates than in cartesian coordinates. In this paper, an algorithm for the recognition of objects with concentric circular noise-patterns is proposed. And position-conrtol information is calculated with the matching result. First, a filtering algorithm for eliminating concentric noise patterns is proposed to obtain concentric-feature patterns. Then a shift, rotation and scale invariant alogrithm is proposed for the recognition and position-control of objects uusing invariant feature information. Experimental results indicate the effectiveness of the proposed alogrithm.