• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.12
• /
• pp.3195-3201
• /
• 1994

In order to analytically predict tapping torque and thrust force in high speed tapping, a cutting model for main cutting edge with a uniformly restricted tool-chip contact area were developed. From this model equations are derived for the prediction of tapping torque given the cutting conditions, tap geometry, and an empirical factor which is related to the workmaterial. Computed values of torque is shown to compare favorably with those obtained from tapping tests on 16MnCr5. The applied torque about the cutting edge of teeth at lead chamfer is estimated respectively and it is shown that observed value is gradually decreased with following teeth.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.1254-1255
• /
• 2006

For precise property control of sintered products, it is important to understand accurately the packing density of the powder. We developed a packing simulation program that could make a packed bed of spherical particles having particle size distribution. In addition, the influence of the particle shape of the actual powder on the packing density was quantitatively analyzed. The predicted packing densities corresponded well to the actual data.

• Journal of the Korean Society of Safety
• /
• v.28 no.3
• /
• pp.6-10
• /
• 2013

The Heat Recovery Steam Generator(HRSG) is a device recycling the exhaust gas of gas turbine in combined power and chemical plants. Since service temperatures was very high, the damage of HRSG tubes intensively occurred in superheater and reheater. The aim of this paper is to determine life and hardness relationship that addresses creep-rupture test and creep-interrupt test in modified 9Cr-1Mo steel. The measured life that consists of function of hardness was found to constant tendency.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2020.11a
• /
• pp.158-159
• /
• 2020

초 고화질 영상의 등장과 동영상 스트리밍 서비스의 폭발적인 이용증가로 고품질로 영상을 압축할 수 있는 기술의 중요성이 크게 증가하고 있다. 본 논문에서는 VVC 차세대 비디오 부호화기술에 따라 색차 블록의 화면 내 예측 시 정확한 예측각도를 측정하여 압축 성능을 더욱 향상시키는 방법을 연구하였다. 실험결과, 기존 VVC 방법 대비 BDBR(Bjontegaard Delta Bit Rate) 측면에서 AI(All Intra) 조건의 경우, Y(-0.01%), Cb(-0.07%), Cr(-0.05%)의 성능변화를 얻을 수 있었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2022.06a
• /
• pp.197-198
• /
• 2022

Versatile Video Coding (VVC)는 차세대 동영상 압축 표준화 과정에서 다수의 부호화 기술을 새롭게 채택하였는데, 이중 Multiple Reference Lines (MRL)을 포함한 일부 기술은 휘도 채널에만 적용될 수 있으며 색차 성분에 대해서는 적용이 고려되지 않는다. 본 논문은 VVC 에서 휘도 채널에만 적용되는 MRL 기술을 색차 채널로 확장하기 위하여, DM(Derived Mode)을 사용하는 색차 블록의 대응 휘도 블록이 MRL 을 사용하는 경우에 해당 참조 라인을 선택적으로 공유하여 색차 블록이 화면 내 예측에 복수개의 참조 라인을 고려하여 선택할 수 있도록 하는 방법을 제안한다. 실험 결과, VVC Test Model (VTM) 15.0 대비 Cb, Cr 성분 각각 -0.09%, -0.05%의 성능 향상을 보인다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.11
• /
• pp.951-956
• /
• 2008

The high temperature creep properties of the generating plant's high temperature tube, pipe and header and such are very significant in accordance with long-time exposure to the high temperature and pressure environment. Not only this, but as the welding procedure is compulsory for the cohesion of components, the creep properties regarding the local microstructures of steel weldment are very important. In order to understand the creep properties regarding the local microstructures of steel weldment, the SP-Creep test which is easy to get sample from the field component was conducted. The local microstructure of steel weldment, that is, W.M. and B.M.'s microstructures were observed using the SEM. The rupture time of W.M. was longer as 110 % averagely in a same condition, which is the consequence of the difference of the microstructure. Each lethargy coefficient of B.M. and W.M. is evaluated by the relation among the temperature, load and the rupture time from SP-Creep Test. The life estimation equation can be induced by the transformation of Power-law. B.M. and W.M. for each $550\;^{\circ}C$ and $575\;^{\circ}C$, the very similar to normal temperature of the domestic thermal power generation in working, are estimated.

• Childhood Kidney Diseases
• /
• v.23 no.2
• /
• pp.105-110
• /
• 2019

Purpose: We sought to determine associations of urinary neutrophil gelatinase-associated lipocalin (NGAL) and liver-type fatty acid-binding protein (L-FABP), known markers of renal injury, with hematuria in children and adolescents. Methods: A total of 112 urine samples from 72 patients aged 2 to 18 years with hematuria were enrolled in this study. Urinary concentrations of NGAL and L-FABP were measured by ELISA and compared between subjects with and without proteinuria and between subjects with and without glomerulonephritis diagnosed by renal biopsy. Results: Urinary concentrations of NGAL and L-FABP/creatinine (Cr) in subjects with proteinuria were not significantly different from those in subjects without proteinuria. They were not significant different between subjects with and without glomerulonephritis either. However, both concentrations of urinary NGAL and L-FABP/Cr were positively associated with urinary protein to creatinine ratio. Their levels had a tendency to be increased when proteinuria developed at later visits in subjects with hematuria only at initial visits. Conclusion: Monitoring urinary NGAL and L-FABP levels in addition to conventional risk factors such as proteinuria and serum creatinine might improve the prediction of renal injury in pediatric patients with hematuria.

• Journal of Korean Society on Water Environment
• /
• v.37 no.6
• /
• pp.442-448
• /
• 2021

Seawater desalination is a technology through which salt and other constituents are removed from seawater to produce fresh water. While a significant amount of fresh water is produced, the desalination process is limited by the generation of concentrated brine with a higher salinity than seawater; this imposes environmental and economic problems. In this study, characteristics of seawater from three different locations in South Korea were analyzed to evaluate the feasibility of crystallization to seawater desalination. Organic and inorganic substances participating in crystal formation during concentration were identified. Then, prediction and economic feasibility analysis were conducted on the actual water flux and obtainable salt resources (i.e. Na2SO4) using membrane distillation and energy-saving crystallizer based on multi-stage flash (MSF-Cr). The seawater showed a rather low salinity (29.9~34.4 g/L) and different composition ratios depending on the location. At high concentrations, it was possible to observe the participation of dissolved organic matter and various ionic substances in crystalization. When crystallized, materials capable of forming various crystals are expected. However, it seems that different salt concentrations should be considered for each location. When the model developed using the Aspen Plus modular was applied in Korean seawater conditions, relatively high economic feasibility was confirmed in the MSF-Cr. The results of this study will help solve the environmental and economic problems of concentrated brine from seawater desalination.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.1D
• /
• pp.45-55
• /
• 2008

The objective of this research was to develop a VEPCD (ViscoElastoPlastic Continuum Damage) Model which is used to predict the behavior of asphalt concrete under various loading and temperature conditions. This paper presents the VEPCD model formulated in a tension mode and its validation using four hot mix asphalt (HMA) mixtures: dense-graded HMA, SBS, CR-TB, and Terpolymer. Modelling approaches consist of two components: the ViscoElastic Continuum Damage (VECD) mechanics and the ViscoPlastic (VP) theory. The VECD model was to describe the time-dependent behavior of HMA with growing damage. The irrecoverable (whether time-dependent or independent) strain has been described by the VP model. Based on the strain decomposition principle, these two models are integrated to form the VEPCD model. For validating the VEPCD model, two types of laboratory tests were performed: 1) a constant crosshead strain rate tension test, 2) a fatigue test with randomly selected load levels and frequencies.

• Journal of the Korean Society of Radiology
• /
• v.84 no.5
• /
• pp.1094-1109
• /
• 2023

Purpose To investigate whether CT-based tumor regression grade (ctTRG) can be used to predict the response to neoadjuvant chemotherapy (NAC) in colon cancer. Materials and Methods A total of 53 patients were enrolled. Two radiologists independently assessed the ctTRG using the length, thickness, layer pattern, and luminal and extraluminal appearance of the tumor. Changes in tumor volume were also analyzed using the 3D Slicer software. We evaluated the association between pathologic TRG (pTRG) and ctTRG. Patients with Rödel's TRG of 2, 3, or 4 were classified as responders. In terms of predicting responder and pathologic complete remission (pCR), receiver operating characteristic was compared between ctTRG and tumor volume change. Results There was a moderate correlation between ctTRG and pTRG (ρ = -0.540, p < 0.001), and the interobserver agreement was substantial (weighted κ = 0.672). In the prediction of responder, there was no significant difference between ctTRG and volumetry (Az = 0.749, criterion: ctTRG ≤ 3 for ctTRG, Az = 0.794, criterion: ≤ -27.1% for volume, p = 0.53). Moreover, there was no significant difference between the two methods in predicting pCR (p = 0.447). Conclusion ctTRG might predict the response to NAC in colon cancer. The diagnostic performance of ctTRG was comparable to that of CT volumetry.