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( Soo-taek Uh ),( So My Koo ),( Yangki Kim ),( Kiup Kim ),( Sungwoo Park ),( An Soo Jang ),( Dojin Kim ),( Yong Hoon Kim ),( Choon-sik Park ) 대한내과학회 2017 The Korean Journal of Internal Medicine Vol.32 No.5
Background/Aims: Diesel exhaust particles (DEPs) lead to elevation of reac-tive oxygen species, which can activate the nucleotide-binding oligomerization domain-like receptor (NLR) family members containing the pyrin domain 3 (NLRP<sub>3</sub>)-inflammasome. In this study, we elucidated whether NLRP<sub>3</sub> -inflam-masome is activated by DEPs and whether antioxidants (N-acetylcysteine [NAC]) could inhibit such activation. Methods: RAW 264.7 cells and ex vivo lung tissues explants obtained from elas-tase-induced emphysema animal models were stimulated with cigarette smoking extract (CSE), DEPs, and lipopolysaccharide, and levels of interleukin-1β (IL-1β), caspase-1 and nucleotide-binding oligomerization domain-like receptor (NLR) family members containing the pyrin domain (NLRP<sub>3</sub>)-inflammasome were as-sessed by Western blotting and immunohistochemistry. Results: NAC and caspase-1 inhibitor suppressed CSE- and DEP-induced secretion of IL-1β in RAW 264.7 cells. The expression levels of the NLRP3-inflammasome and caspase-1 were upregulated in RAW 264.7 cells by stimulation with CSE and DEPs and were inhibited by NAC. CSE and DEPs increased the secretion of IL-1β in lung tissues from both the normal and elastase-induced emphysema groups. The secretion of IL-1β by CSE and DEPs was increased in the elastin-induced em-physema group more than that in the normal group (CSE: 309 ± 19 pg/mL vs. 151 ± 13 pg/mL, respectively, p < 0.05; DEP: 350 ± 24 pg/mL vs. 281 ± 15 pg/mL, respective-ly, p < 0.05). NAC inhibited CSE- and DEP-induced IL-1β secretion in both the nor-mal and elastase-induced emphysema groups. NLRP<sub>3</sub>-inflammasome expression as determined by immunohistochemistry was increased by CSE and DEPs in both the normal and elastin-induced emphysema groups, and was suppressed by NAC. Conclusions: The NLRP<sub>3</sub>-inflammasome is activated by DEPs in ex vivo tissue explants from elastase-induced emphysema animal model, and this activation is inhibited by NAC.
자긴가공된 SCM440 고강도강의 잔류응력평가에 관한 연구
김재훈(Jaehoon Kim),심우성(Woosung Shim),윤용근(Youngkwen Yoon),이영신(Youngshin Lee),차기업(Kiup Cha),홍석균(Suckkyun Hong) 한국추진공학회 2010 한국추진공학회지 Vol.14 No.4
Thick-walled cylinders, such as a cannon or nuclear reactor, are autofrettaged to induce advantageous residual stresses into pressure vessels and to increase operating pressure and the fatigue lifetimes. As the autofrettage level increases, the magnitude of compressive residual stress at the bore also increases. The purpose of the present paper is to predict the accurate residual stress of SCM440 high strength steel using the Kendall model which was adopted by ASME Code. Hydraulic pressure process was applied in the inner part and thick-walled cylinders were autofrettaged up to 30% overstrain levels. Electro polishing on the surface of autofrettage specimen was performed to get more accurate residual stress. Residual stresses were measured by X-ray diffraction method. The autofrettage surface which was plastically deformed analyzed using a scanning electron microscope(SEM). Although there were some differences in measured residual stress and numerical results, it has a tendency to agree comparatively with each other.
ER 유체를 이용한 회전식 약실 축계의 비틀림 진동 제어
임승철(Seungchul Lim),김기갑(Kikap Kim),길성진(Seongjin Kil),심정수(Jeongsoo Shim),차기업(Kiup Cha) 대한기계학회 2011 大韓機械學會論文集A Vol.35 No.1
간헐 회전식 약실 계가 화력 대 무장 공간의 비율 관점에서 볼 때 중구경 자동포에 크게 유익하다고 보고되었다. 그러나 약실계의 핵심 부품인 평행 인덱스가 인덱스 터릿에 설치되는 캠종동절의 상대적으로 낮은 횡 강성으로 인하여 비틀림 방향으로 유연해지는 경향이 있으며, 이는 결국 터릿과 약실 사이의 연결 축이 상당한 크기의 비틀림 잔류 진동에 노출되어 탄 장전과 발사 시에 심각한 비정렬 문제를 야기시킬 수 있다. 이러한 맥락에서 본 논문에서는 상기 진동을 억제하는 ER유체 작동기와 그에 적합한 반능동 제어 알고리듬을 제안하게 되었으며, 전체 계의 수학적 모델링과 컴퓨터 시뮬레이션을 통하여 그 성능이 만족스러움을 입증하였다. It is reported that an intermittently rotating chamber system will improve the ratio of firepower to armament space in the case of mid-calibre automatic guns. However, the parallel index, which is a main component of the system, tends to be torsionally flexible due to the low lateral stiffness of cam followers on the index turret. This may cause the shaft system connecting the turret with the chamber prone to considerable residual torsional vibration so that serious misalignment problems occur during ammunition loading and firing processes. Herein, an electrorhelogical (ER) fluid actuator that can suppress such vibrations and the associated semiactive control algorithm are proposed. By mathematical modeling and computer simulations, the performance of the entire system is proved satisfactory.
심우성(Woosung Shin),김재훈(Jaehoon Kim),이영신(Youngshin Lee),차기업(Kiup Cha),홍석균(Sukkyun Hong) 한국추진공학회 2008 한국추진공학회지 Vol.12 No.4
In manufacturing aircraft, safety and lightness of structure are important factors. Utilizing autofrettage technique, these benefits can be obtained. This technique is most frequently applied to a single cylinder. However, the Bauschinger effect reduces the benefits of autofrettage process Therefore, there is increasing interest in the use of compound cylinder that combine shrink fit and autofrettage. In this paper, single and compound cylinders that has same geometry were considered. It was found that compound cylinder which was autofrettaged has lower tangential hoop stress and plastic strain than single cylinder at bore. This means a reduction in the impact of the Bauschinger effect after shrink-fitting which produces the beneficial bore hoop stress.