• 한국주조공학회지
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• 제30권4호
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• pp.130-136
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• 2010

Sulfide segregation behavior, characteristics of solidification microstructure and compositional distribution in the riser/castings junction of heavy-section main bearing support (MBS) steel castings were investigated; Sulfide streaks of A segregation were formed in the transitional region from columnar grain to coarse equiaxed grain and floated with aggregation of the dendritic free crystal. Solute segregation behaviors of elements Si, P and S were V shape negative segregation from the bottom of the castings to upper part of the riser with the reference of vertical center-line of the specimen block. Those of elements C and Mn were V shape negative segregation in the main body and A shape positive segregation in the riser of the casting. Just beneath the pipe shrinkage in the riser segregation ratio of each element was the highest, and that of S was 3.6 times higher, C 3.3 times, P 2.1 times, Si 1.6 times and Mn 1.0 times respectively. [Mn/S] ratio of the specimen block was distributed in the wide range of 20~275.

• Journal of Welding and Joining
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• 제28권4호
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• pp.41-48
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• 2010

The purpose of this study is to establish the control method of the global bending distortion caused by fabrication process of hatch-cover in a container ship. In order to do it, the transitional behavior of global bending distortion in the deck of hatch-cover during fabrication process was measured by 3-dimensional measuring instrument. From the results, the principal factor controlling the global bending distortion was identified as the bending moment associated with the longitudinal shrinkage force and transverse shrinkage caused by welding and flame heating and the change of the centroid axis of hatch-cover in each fabrication process. Therefore, in this study, with the predictive equations of the longitudinal shrinkage force and transverse shrinkage caused by welding and flame heating and the simplified thermo elastic method, the predictive method for the global bending distortion was established and verified by comparing with the measured result. Based on the results, the amount of reverse bending distortion of main stiffeners was determined to prevent the global bending distortion of hatch-cover.

• Transactions on Electrical and Electronic Materials
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• 제18권4호
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• pp.211-216
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• 2017

The dielectric properties of two polyurethanes (PUs) with different hard segments, i.e., aromatic methylene di-p-phenyl diisocyanate (MDI) and aliphatic hexamethylene diisocyanate (HDI), were investigated in the temperature range of -100 to $100^{\circ}C$ and in the frequency range of 1 Hz to 3 kHz. The ${\alpha}$-relaxations induced by the glass transition of the equivalent soft segments in the two PUs occurred at relaxation times of ${\tau}=3.46{\times}10^{-3}s$ for MDI-PU and ${\tau}=3.39{\times}10^{-2}s$ for HDI-PU at $-20^{\circ}C$, in accord with the temperature-frequency superposition principle, resulting in similar shifting factors. However, different I-relaxations were observed for the two PUs. The I-relaxation of MDI-PU occurred due to the mobility of the chain extenders near $80^{\circ}C$ with a slower shifting rate than the ${\alpha}$-relaxation. On the other hand, I-relaxation arising from both the extender and the unconstrained hard segments of HDI-PU occurred at $70{\sim}100^{\circ}C$, indicating complicated dielectric behavior due to partial interaction with the ${\alpha}$-relaxation at high frequencies. Thus, the I-relaxation of HDI-PU did not follow the superposition principle. The dielectric behaviors of the PUs were mainly influenced by their phase transitions, which were affected by the structure and components of the materials.

• East Asian Economic Review
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• 제21권3호
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• pp.201-230
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• 2017

This paper studies the long-run behavior of relative price dispersion among cities in Korea with a special emphasis on heterogeneous transitional patterns of price level dynamics. Formal statistical tests indicate considerable evidence for rejecting the null of relative price level convergence among the majority of cities over the sample period of 1985-2015. The analysis of gravity model suggests that the effect of transportation costs on intercity price level differentials is limited, while other socioeconomic factors, such as income, input factor prices, demographic structure, and housing price growth, play key roles in accounting for persistent regional price level disparities. Individual price levels are found to be better explained by a multiple-component model, and the deviations from PPP may be attributed to distinct stochastic common trends that are characterized by income and demographic structure.

• Journal of Welding and Joining
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• 제14권1호
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• pp.38-46
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• 1996

High temperature low cycle fatigue crack growth behavior is investigated over a range of two temperatures and various frequencies in SUS 304 stainless steel. It is found that low frequency and temperature can enhance time-dependent crack growth. With high temperature, low frequency and long crack length, ${\Delta}J_c/{\Delta}J_ f$, the ratio of creep J integral range to fatigue J integral range is increased and time-dependent crack growth is accelerated. Interaction between ${\Delta}J_f$ and ${\Delta}J_c$ is occured at high frequency and low temparature and ${\Delta}J_c$, creep J integral range is fracture mechanical parameter on transition from cycle-dependent to time dependent crack growth in creep temperature region.

• 한국연소학회지
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• 제21권1호
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• pp.31-37
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• 2016

Swirler generates the overall swirling flow in the combustion chamber and this swirling flow governs the flame stability and enhances fuel atomization. This paper deals with the flare angle effects on flow streamlines, recirculation zone, Central Toroidal Recirculation Zone(CTRZ) and Corner Recirculation Zone(CRZ) in the model combustion chamber using counter-rotating swirler. 2D PIV system was employed to obtain the velocity components and test condition was obtained using Reynolds Analogy equivalent to air test. We observed transitional flow patterns of flare angle increased. The obtained results show that the flare angle controls the behavior of Recirculation zone, Central Toroidal Recirculation Zone and Corner Recirculation Zone.

• 응용통계연구
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• 제27권2호
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• pp.263-275
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• 2014

본 연구에서는 비동차 마코프 체인에서 개체들의 전이 행태를 분석하기 위한 계층적 베이지안 방법론을 사용하여 혼합 효과 모델을 소개 하였다. 모델의 모수들에 대한 사후분포가 분석적으로 구해질 수 없는 형태를 가지기 때문에 깁스(Gibbs) 샘플링 시뮬레이션 방법을 사용하여 조건부 사후확률로부터 샘플이 추출되었고, 실제 자료분석을 예를 사용하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.60-62
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• 2005

The purpose of this study is to evaluate the effect of spot heating on the fatigue strength at the weldment. To do this, the transitional behavior of residual stress at the weld toe induced by spot heating was identified using FEA and experiment. The amount and distribution of residual stress at the weld toe strongly depends on the locations of spot heating. Based on the results, the proper spot heating condition was established. The fatigue strength of the spot-heated specimen increases compared with as-welded specimen.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1445-1456
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• 2003

The ASTER TIR (thermal infrared radiometer) sensor has 5 spectral bands over 8 to 12 ${\mu}$m region. Rock type classification using the ASTER TIR nighttime data was performed in the Erta Ale range of the Ethiopian Rift Valley. Erta Ale range is the most important axial volcanic chain of the Afar region. The petrographic diversity of lava erupted in this area is very important, ranging from magnesian transitional basalt to rhyolites. We tried to classify the rock types based on the spectral behavior of each volcanic rock types in thermal infrared range and estimated SiO$_{2}$ content with emission data by the ASTER TIR.

• Journal of Korean Neurosurgical Society
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• 제29권9호
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• pp.1215-1221
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• 2000

목 적 : 양성 뇌수막종에 비하여 이형성 및 악성 뇌수막종이 나쁜 임상적인 예후 및 양상을 보이는 것은 잘 알려져 있으나, 양성 뇌수막종에 있어서 각각의 병리조직학적 아형에 따른 생물학적 양상의 차이에 대해서는 잘 알려지지 않거나 일부 논란이 되고있다. 본 연구에서는 이형성 뇌수막종 및 양성 뇌수막종의 각각의 병리조직학적 아형에 따른 증식능의 차이여부를 알아보고자 PCNA와 Ki-67표지지수를 분석하였다. 방 법 : 본원에서 뇌수막종으로 수술을 시행하여 얻은, 재발을 보여 재수술을 시행한 2례를 포함하여, 파라핀에 포매시킨 27개의 조직을 대상으로 병리학적인 증식능을 분석하기 위해, PCNA에 대한 단일항체 및 MIB-1 단일항체를 이용한 면역조직화학적 염색을 시행하였다. 조직학적 분류상 meningothelial type이 8례, transitional type이 9례, fibroblastic type이 5례였으며, 이형성 수막종이 5례였다. 결 과 : PCNA표지지수의 평균값은 양성 수막종에서 meningothelial type이 $4.82{\pm}5.10%$, transitional type이 $9.01{\pm}4.25%$, fibroblastic type이 $5.66{\pm}5.32%$를 보였으나 이형성 수막종에서는 $27.62{\pm}19.67%$의 높은 지수를 나타냈고, Ki-67 표지지수의 평균값은 양성 수막종의 아형에서 각각 $0.43{\pm}0.85%$, $0.44{\pm}1.08%$, $0.24{\pm}0.18%$를 보이고, 역시 이형성 수막종에서는 $0.84{\pm}0.59%$의 높은 지수를 보였다. 즉, 양성 수막종에서 각각의 아형에 따른 PCNA 및 Ki-67 표지지수는 통계학적으로 의미있는 차이는 없었으나(p>0.05), 이형성 수막종에서는 의미있는 높은 표지지수를 보여(p<0.05) 양성 수막종에서 보다 높은 증식능을 보임을 알 수 있었다. 결 론 : PCNA 및 Ki-67 표지지수를 이용한 증식능의 비교결과, 양성 뇌수막종에서는 각각의 아형에 따른 생물학적 양상이나 예후는 차이가 없을것으로 생각되나, 이형성 수막종에서는 높은 증식능을 보여 이에 대한 예후를 예상할 수 있을것으로 생각되며, 또한 이러한 표지지수가 병리조직학적으로 양성과 이형성의 감별에 많은 도움이 될것으로 사료된다.