• Journal of Korean Society of Industrial and Systems Engineering
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• v.8 no.12
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• pp.89-95
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• 1985

MRP System에서 시스템 성능을 향상시킬 수 있는 하나의 인자는 우수한 Lot-Sizing rule의 선택과 발견이다. 널리 사용되고 있는 Lot-Sizing rule 들 중 Wagner-Whitin 알고리즘은 생산준비 비용과 재고 유지비용이 가변적일 경우 동적 로트크기 결정에 우수한 forward 알고리즘이다. 본 연구에서는 Wagner-Whitin 알고리즘의 중요 원리들을 응용하여 LDS 알고리즘이라 명명한 backward 알고리즘을 개발한다. 그리고 개발된 알고리즘을 Wagner-Whitin 알고리즘과 비교함으로 그 유효성을 테스트하고 backward 알고리즘이 가지는 계산상의 장점을 고찰한다.

• Journal of the Korean Society of Safety
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• v.4 no.1
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• pp.103-120
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• 1989

최근 도시교통계획분야에 있어서 교통수요의 예측모델 또는 교통정책의 평가 모델로서 비집계(非集計) 모델에 관한 연구가 진행되고 있다. 이 비집계모델은 개개의 의사결정단위에 있어서 선택행동을 영역마다 집계하는 것이 아니고 의사결정레벨의 데이터률 그대로 모델로 구성할 경우 이 데이터를 이용함으로써 의사결정단위의 선택행동을 모델화 할 수 있다는 특징을 갖고 있다. 한편 비집계모델의 사용목적은 여러가지로 생각되나 이것을 교통수요의 목적이나 교통정잭의 평가를 위한 모델로 이용할 때는 파라미터의 추정값이나 선택비율의 추정값에 대한 안정성이 매우 중요한 문제가 되고 있다.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.180-181
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• 2003

Czochralski 방법으로 KMg $F_3$：S $m^{2+}$ 결정을 성장시키고 고 분해 레이저 분광법을 이용하여, 형광특성을 조사하였다. S $m^{2+}$ 이온이 KMg $F_3$ 결정에서 $C_{4v}$, $C_{2v}$, $C_{3v}$ 및 $O_{h}$ 형광 방출 사이트를 가진다는 것을 확인하였고, 아울러 각 사이트의 에너지 준위를 구하였다. 구하였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.518-523
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• 1998

The fracture toughness and hardness of 62 %$SiO_2-19%ZrO_2-9%Na_2O-10%B_2O_3$(wt%) glass ceramics system were investigated. As a result of DTA study to find crystallization temperature, an exothermic peak near $820^{\circ}C$ was observed. The optimum nucleation temperature and the optimum crystal growth temperature were determined by XRD and SEM analysis, and were approximately $650^{\circ}C$, $840^{\circ}C$ respectively. The fracture toughness of this zirconia glass ceramics was determined by Vickers Indentation Method. The hardness value was not changed with increasing of the heat treatment temperature, but fracture toughness value was increased up to $1.8 MPa{\cdot}m^{1/2}$ at $840^{\circ}C$, with increasing of heat treatment temperature.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.25-32
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• 2009

The glass-ceramics composed of coal bottom ash produced from a thermal power plant, $Na_{2}O$ and $Li_{2}O$ as a flux agent and $TiO_2$ as a nucleation agent were fabricated and its microstructures were analyzed. The nepheline was a major crystal phase in the glass-ceramics fabricated and its amount increased with $TiO_2$ addition. The glass-ceramics without $TiO_2$ addition had the thick surface crystals induced by a surface-crystallization mechanism and no crystal in the interior matrix. The surface crystallization, however, was restrained and the interior matrix was completely crystallized showing dendrite shape spread with fine particles < $1{\mu}m$ when added with $TiO_2$ above 4 wt%. For the glass-ceramics containing 6 wt% $TiO_2$, the $5{\mu}m$-long dendrite crystal; were interlocked each other which could suppress the crack propagation effectively at the external loading applied.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.6
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• pp.240-246
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• 2021

In the ceramic industry, a drastic decrease in crystalline formation was found even among the glazes well known for their high crystalline productivity when the ceramic glaze was stored in wet conditions over a period. This study aimed to investigate the reason for decreasing willemite crystals during storage. As the starting materials ZnO, calcined ZnO and frit 3110 are selected; the composition for zinc crystalline glazes was set through a three-component system with the materials. The firing condition was used from previous studies. The study was observed how wet conditions affected the crystallization of zinc crystalline glazes from a day to 24 weeks. The results were obtained by particle size analysis, XRD, Raman spectroscopy and SEM analysis. The results indicated that ZnO is advantageous in terms of willemite crystalline development and growth; however, Zn(OH)₂ cluster, formed by the reaction with water during the storage, caused the decrease in ZnO level in the glaze. The reduction of ZnO in the glaze eventually interfered the willemite development and growth.

• Korean Journal of Crystallography
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• v.17 no.2
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• pp.55-59
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• 2006

• Korean Journal of Crystallography
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• v.17 no.1
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• pp.19-23
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• 2006

• Korean Journal of Crystallography
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• v.18 no.1_2
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• pp.7-9
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• 2007

The equations for the calculation of the crystallographic interplanar angles for the seven crystal systems are described using only the real crystal unit cell parameters.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.106-110
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• 1998

본 논문에서는 먼저 다층흡착에서 각 흡착층의 결합에너지가 서로 다른 경우의 흡착 등온선을 유도한다. 그리고 유도된 흡착등온식이 저압영역에서 헨리의 실험법칙을 잘 만족시킴을 보인다.