• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.357-360
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• 2009

The cooling stage greatly affects the product quality in the injection molding process. The cooling system that minimizes temperature variance in the product surface will improve the quality and the productivity of products. In this research, we tried the back-propagation algorithm of artificial neural network to find an optimum solution in the cooling system design of injection mold. The cooling system optimization problem that was once solved by a response surface method with 4 design variables was solved by applying the back-propagation algorithm, resulting in a solution with a sufficient accuracy. Furthermore the number of training points was much reduced by applying the fractional factorial design without losing solution accuracy.

• 대한의용생체공학회:의공학회지
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• 제14권3호
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• pp.257-264
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• 1993

A study on the biocompatibility of two types of new glass-ceramics materials, metal disc and dental porcelain that were already made for dental artificial tooth in the previous study, have been attempted. The chemical behavior and the Victor's hardness change in she artificial saliva and Ringer's solution have been also investigated. From the experiment of Implantation of glass-ceramics Into dorsal subcutaneous tissue of Sprague-Dawley rats, glass-cerarmics did not show any particular system of rejection for histrocompatibility.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제25권4호
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• pp.149-161
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• 2021

This study proposes a methodology for mission/path planning of an unmanned aerial vehicle (UAV) using an artificial potential field with the Markov Decision Process (MDP). The planning problem is formulated as an MDP. A low-resolution solution of the MDP is obtained and used to define an artificial potential field, which provides a continuous UAV mission plan. A numerical case study is conducted to demonstrate the validity of the proposed technique.

• 한국안광학회지
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• 제21권3호
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• pp.191-201
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• 2016

목적: 성분 조성이 다른 인공눈물들이 소프트콘택트렌즈를 착용한 건성안의 착용 초기 눈물막 안정성 및 자각증상에 미치는 영향을 알아보았다. 방법: Etafilcon A 재질의 소프트콘택트렌즈를 착용한 50안의 건성안에 성분 조성이 다른 3종의 인공눈물 용액 및 식염수를 각각 점안하고 비침습성 눈물막 파괴시간(NIBUT)를 인공눈물 점안한 직후부터 30분까지 5분 간격으로 측정하였고, 점안 30분후의 순목 횟수 및 자각증상 변화를 알아보았다. 결과: 3종의 인공눈물 모두 식염수보다 NIBUT를 더 크게 증가시켰다. 인공눈물 점안 직후의 NIBUT 증가 효과는 점성조절제가 포함된 인공눈물에서 가장 컸으며, 효과지속 시간은 계면활성제와 점성조절제가 모두 포함된 인공눈물이 가장 길었다. 순목 횟수는 인공눈물 용액과 식염수 점안시 모두 통계적으로 유의한 변화가 없었다. 자각적 증상은 인공눈물 및 식염수 점안으로 모두 통계적으로 유의하게 향상되었으며 대부분의 용액에 의해 건조감, 이물감, 피곤감, 뻑뻑함, 눈시림 증상의 향상이 나타났다. 점안 30분 후에는 인공눈물 점안전의 자각증상과 유사한 수준으로 복귀하였다. 결론: 건성안의 소프트콘택트렌즈 착용 초기 자각 증상은 인공눈물과 식염수 모두 완화시켜주지만 눈물막의 안정성에 미치는 효과는 함유 성분에 따라 차이가 있음을 밝혔다. 본 연구결과를 통하여 콘택트렌즈 착용 건성안의 착용 초기 안구건조증 개선을 위해서는 적절한 인공눈물의 선택이 필요함을 제안한다.

• 산업경영시스템학회지
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• 제42권1호
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• pp.87-94
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• 2019

A wireless sensor network is emerging technology and intelligent wireless communication paradigm that is dynamically aware of its surrounding environment. It is also able to respond to it in order to achieve reliable and efficient communication. The dynamical cognition capability and environmental adaptability rely on organizing dynamical networks effectively. However, optimally clustering the cognitive wireless sensor networks is an NP-complete problem. The objective of this paper is to develop an optimal sensor network design for maximizing the performance. This proposed Ranking Artificial Bee Colony (RABC) is developed based on Artificial Bee Colony (ABC) with ranking strategy. The ranking strategy can make the much better solutions by combining the best solutions so far and add these solutions in the solution population when applying ABC. RABC is designed to adapt to topological changes to any network graph in a time. We can minimize the total energy dissipation of sensors to prolong the lifetime of a network to balance the energy consumption of all nodes with robust optimal solution. Simulation results show that the performance of our proposed RABC is better than those of previous methods (LEACH, LEACH-C, and etc.) in wireless sensor networks. Our proposed method is the best for the 100 node-network example when the Sink node is centrally located.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1997년도 추계학술대회발표논문집; 홍익대학교, 서울; 1 Nov. 1997
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• pp.52-55
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• 1997

In this paper, both the generalization of one artificial variable technique to the general bound problem and the efficient implementation of the technique are suggested. When the steepest-edge method is used as a pricing rule in the simplex method, it is easy to update the reduced cost and the simplex multiplier every iteration. Therefore, one artificial variable technique is more efficient than Wolfe's method in which the reduced cost and simplex multiplier must be recalculated in every iteration. When implementing the one artificial variable technique on the LP problems with the general bound restraints on the variables, an arbitrary basic solution which satisfies the bound restraints is sought first, and the artificial column which adjusts the infeasibility is introduced. The phase one of the simplex method minimizes the one artificial variable. The efficient implementation technique includes the splitting, scaling, storage of the artificial column, and the cure of infeasibility problem.

• Restorative Dentistry and Endodontics
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• 제19권2호
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• pp.534-548
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• 1994

The purpose of this study is to observe the corrosion characteristics of seven dental amalgams (CAULK FINE CUT, CAULK SPHERICAL, OPTALLOY II, DISPERSALLOY, HI VERALOY, TYTIN, VALIANT) through the anodic polarization curve obtained by using a potentiostat. After each amalgam alloy and Hg being triturated, the triturated mass was inserted into the cylindrical metal mold, and condensed by hydrolic pressure(160 kg/$cm^2$). Each specimen was removed from the metal mold. 24 hours after condensation, specimens were polished with the emery paper and stored at room temperature for 1 week. The anodic polarization curves were employed to compare the corrosion behaviours of the amalgam in 0.9% saline solution, Fusayama's artificial saliva, and stimulated parotid saliva at $37^{\circ}C$ with 3-electrode potentiostat. After the immersion of specimen in electrolyte for 1 hour, the potential scan was begun. The potential scan range was. -1700m V ~ + 400m V(vs. S. C. E) in the working electrode and the scan rate was 50m V /sec. The results were as follows, 1. The corrosion potential, the potential of anodic current peak, and transpassive potential in the stimulated parotid saliva shifted to more anodic direction than those in saline solution, and the current density in the stimulated parotid saliva was lower than that in saline solution. Those in Fusayama's artificial saliva was similar to those in stimulated parotid saliva. 2. The anodic polarization profiles in Fusayama's artificial saliva and stimulated parotid saliva indicated a region of slow slope current density, which is extending from the corrosion potential to the potential of anodic current peak, but that in 0.9% saline solution indicated no region of slow slope. 3. The corrosion potentials for CAULK FINE CUT, CAULK SPHERICAL, and OPT ALLOY II had the similarity in 0.9% saline solution, Fusayama's artificial saliva and stimulated parotid saliva, but those for high coper amalgam and VALIANT had no similarity. 4. The current density for TYTIN amalgam in stimulated parotid saliva was the lowest among the others. 5. As for current density, there was no significant difference between palladium enriched VALINAT and other high copper amalgams.

• 한국소음진동공학회논문집
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• 제12권6호
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• pp.478-487
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• 2002

This paper presents a hybrid method to compute the solutions of an optimization Problem. The present hybrid algorithm is the synthesis of an artificial life algorithm and the random tabu search method. The artificial life algorithm has the most important feature called emergence. The emergence is the result of dynamic interaction among the individuals consisting of the system and is not found in an individual. The conventional artificial life algorithm for optimization is a stochastic searching algorithm using the feature of artificial life. Emergent colonies appear at the optimum locations in an artificial ecology. And the locations are the optimum solutions. We combined the feature of random-tabu search method with the conventional algorithm. The feature of random-tabu search method is to divide any given region into sub-regions. The enhanced artificial life algorithm (EALA) not only converge faster than the conventional artificial life algorithm, but also gives a more accurate solution. In addition, this algorithm can find all global optimum solutions. The enhanced artificial life algorithm is applied to the optimum design of high-speed, short journal bearings and its usefulness is verified through an optimization problem.

• Restorative Dentistry and Endodontics
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• 제13권2호
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• pp.221-235
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• 1988

The purpose of this study was to observe characteristic properties through the polarization curves and EMPA images from 4 different types of amalgam obtained by using the potentiostats (EG & G PARC) & EPMA (Jeol JSM-35), to investigate the degree of corrosion of each phase of amalgam on the oxidation peak, and to identify corrosion products from the corroded amalgam by use of X-ray diffractometer(Rigaku). After each amlgam alloy and Hg were triturated as the direction of the manufacturer by means of the mechanical amalgamator(Shofu), the triturated mass was inserted into the cylindrical metal mold which was 12mm in diameter and 10mm in height and was condensed by means of routine manner. The specimen was removed from the mold and stored at room temperature for about 7 days. The standard surface preparation was routinely carried out. Anodic polarization measurement was employed to compare the corrosion behaviours of the amalgams in 0.9% saline solution(pH6.8~7.0) and artificial saliva (pH6.8~7.0) at $37^{\circ}C$. The open circuit potential was determined after 30 minutes' immersion of specimen in electrolyte and the potential scan was begun at the potential of 100mV cathodic from the corrosion potential. The scan rate was 1mV/sec and the surface area of amalgam exposed to the solution was 0.64$cm^2$ for each specimen. All the potentials reported are with respect to a saturated calomel electrode (SCE). EPMA images on the determined oxidation peaks of each amalgam in artificial saliva were observed. X-ray diffraction patterns of each sample were recorded before and after polarization in artificial saliva (Aristaloy, Caulk Spherical, Dispersalloy and Tytin: at +770mV, +585mV, +8.10m V and +680m V respectively) by use of a recording diffractometer. Nickel filtered Cu $K_{{\alpha}_1}$ radiation was used and sample was scanned at $4^{\circ}(2{\theta})/min.$ from $25^{\circ}$ to $80^{\circ}$. The following results were obtained. 1. Oxidation peak potential in artificial saliva shifted to more anodic direction than that in saline solution. 2. The corrosion potential of high copper amalgam was more anodic than the potential of low copper amalgam. 3. The current density was lower in artificial saliva than in saline solution. 4. One of the corrosion products, AgCl was identified by X-ray diffraction analysis. 5. ${\gamma}_2$ phase was the most susceptible to corrosion and e phase was stable in low copper amalgam and ${\eta}$' phase and Ag-Cu eutectic were susceptible to corrosion in high copper amalgam.

• 한국농공학회지
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• 제40권4호
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• pp.77-84
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• 1998

Adsorption and leaching characteristics of the artificial soils produced from water and wastewater treatment sludges were examined. The batch adsorption test and TCLP leaching test were used, and constituents of interest were heavy metals and nutrients. As, Cr, Cu, Pb, and Cd were analyzed for metals, and nitrogen and phosphorus were analyzed for nutrients. All the artificial soils showed strong adsorption and low leaching for the heavy metals, which implies that the artificial soils may not be hazardous to the environment due to heavy metals and even they can be utilized effectively to remove metals in solution like mine and industrial wastewaters. This is quite promising result because in most case heavy metals are the most concern in the application of sludge product to the farmland. For the nutrients, generally, artificial soils showed high adsorption and low leaching except artificial soil from wastewater sludge produced by low temperature firing. The artificial soils produced from water treatment sludge were active in adsorbing nutrients and showed low leaching that they can be practically used to remove nutrients in advanced treatment process of the wastewater. The artificial soils produced from wastewater treatment sludge were less active in adsorbing nutrients and showed high teaching. However, they could be used usefully if applied properly to the plant growing because of their fertilizing effect. Based on the test results, overall, the artificial soils were thought to be not hazardous to the environment and they could be more useful if applied properly.