Effects of Test Temperature on Low Cycle Fatigue Behaviors in Large Mold Steel

Jong‑Ho Shin,Jehyun Lee 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

A mold steel for plastic injection was subjected to low cycle fatigue (LCF) tests at temperatures of 25, 200, and 250 °C. LCFtests were carried out at a total strain amplitude (Δεt/2) from 0.004 to 0.012 under a constant strain rate of 0.01 s–1. Transmissionelectron microscope images showed that cyclic loading accelerated dislocation recovery as the LCF test temperatureincreased. The LCF life increased as a result of improvement in the ductility associated with dislocation recovery as the testtemperature increased. The LCF behavior at the test temperature range followed the Coffin–Manson equation. Empiricalequation was proposed to predict the LCF life of the mold steel within the test temperature range.

Modified Microstructure Selection Map and Growth Conditions of the Band Structure in Directionally Solidified Hypo-Peritectic Alloys

Jong‑Ho Shin,Jehyun Lee 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

Considering the variation of the solid/liquid interface morphology with a growth condition, microstructure selection map inperitectic system was modified by comparing growing α (primary phase) interface tip temperature and β (peritectic phase)nucleation temperature. The results were proved experimentally in hypo-peritectic Sn–Cd alloys by delicate directionalsolidification experiment under the diffusive growth condition using capillary thin tube. When β-phase took over α-phaseand grew a short distance as the leading phase, the instability of β-phase was first observed experimentally. This phenomenawas explained by constitutional undercooling, which was present temporarily in liquid ahead of the β/l interface.

Nrf2-Heme oxygenase-1 modulates autophagy and inhibits apoptosis triggered by elevated glucose levels in renal tubule cells

Joo Heon Kim,김경민,Jin Uk Jeong,Jong-Ho Shin,신재민,방기태 대한신장학회 2019 Kidney Research and Clinical Practice Vol.38 No.3

Background: Autophagy is a highly balanced process in which lysosomes remove aged and damaged organelles and cellular proteins. Autophagy is essential to maintain homeostasis in the kidneys. Methods: Using human renal tubule cells HK-2, we assessed the impact of high glucose (HG) on autophagy. We also evaluated the capability of sulforaphane (SFN) to protect the HK-2 cells from HG-induced apoptosis by modulating autophagy. Results: SFN modulated autophagy and decreased apoptosis in the HK-2 cells that were cultured in 250 mM glucose medium for two days. The reactive oxygen species (ROS) levels increased, as expected, in the cells cultured in the 250 mM glucose medium. However, the SFN decreased the ROS levels in the HK-2 cells. The overexpression of heme oxygenase-1 (HO-1) by SFN decreased the expression of LC3 and beclin-1. LC3 and beclin-1 were involved in the downregulation of caspase-3 that was observed in the HG-induced cells. Conclusion: The activation of nuclear factor E2-related factor 2 (Nrf2)-HO-1 inhibited ROS expression and subsequently attenuated autophagy and cell apoptosis after HG injury was decreased. HG injury led to the activation of autophagy and HO-1 in order to combat oxidative stress and protect against cell apoptosis. Therefore, HO-1 activation can prevent ROS development and oxidative stress during HG injury, which considerably decreases autophagy and apoptosis.

척수신경세포에서의 아포프토시스 관련인자에 관한 면역조직화학 연구

김종민,정윤희,신정민,박경한,조사선,백상호,차중익 대한해부학회 1999 Anatomy & Cell Biology Vol.32 No.4

중부지역 옥수수 파종기에 따른 생육단계 및 수량성 변화

서종호, 문중경, 정건호, 서민정, 구자환, 박장환, 배환희, 신성휴, 권영업 忠北大學校 農業科學硏究所 2014 農業科學硏究 Vol.30 No.2

Maize hybrids were planted on April 1, April 25, May 20 and June 15 in 2012, 2013 at the experimental paddy and upland fields in Suwon city , respectively to know changes of growth stage and yield according to different planting time. Maize planting on April 1 was not recommended because total growing days at planting on April 1 was not different with that at planting on April 25 due to many days from planting to emergence over 20 days at planting on April 1. Total growing days were not much different among three planting time after April 25 because days from silking to maturity was lengthened though days from planting to silking was shortened at later planting time. Stalk weight was decreased as planting time was delayed, particularly at planting times after May 20 at paddy field by excess water injury during early growth stage. But, grain yield was not low as in May and June. It is needed to introduce early maturity maize variety as Yanganok at late planting for higher grain yield and enough time for soil preparation for next winter crops

LCA 기법을 적용할 제품의 우선순위 선정 방법론

신동희,권은선,문승식,김만영,정종연,허진호 한국전과정평가학회 2004 한국전과정평가학회지 Vol.5 No.1

본 연구의 목적은 일정한 논리적 절차를 거쳐서 객관적인 전과정평가의 우선순위를 선정하기 위한 일반적인 방법론의 개발이다. 우선 전과정평가 대상이 되는 제품(산업군)의 우선순위를 평가하기 위해서 제품의 환경성과 관련된 환경규제, 국내외 전과정평가 수행사례, 유해물질 등을 평가항목으로 설정하였다. 설정된 평가항목들에 대한 자료조사 및 분석을 통하여 세분화한 데이터베이스를 생성하였으며, 또한 학계 및 산업계의 의견을 반영하기 위해 전과정평가 전문가 및 산업계 관계자들을 대상으로 설문조사를 실시하였다. 설문조사결과를 바탕으로 각각의 평가항목 및 세부평가항목의 가중치를 부여하였고, 각 평가항목별로 점수를 설정하였다. 본 연구에서 개발한 방법론은 우선순위를 비교해야하는 제품(산업군)들이 각각의 평가항목에서 설정해놓은 해당 점수를 부여받게 된다. 부여받은 각 평가항목의 점수들을 모두 합산하면 평가대상이 되는 제품(산업군)에 대해 하나의 우선순위 평가 점수를 갖게 된다. 이와 같은 과정으로 방법론이 구축되었으며, 사례연구를 통하여 방법론의 타당성을 검증하였다. 이렇게 산출된 우선순위 평가점수를 평가하고자하는 제품(산업군)들과 비교하여 높은 점수를 갖는 제품(산업군)이 전과정평가를 먼저 실시하는 것이 바람직하다는 결론을 얻을 수 있다. The purpose of this study is to develop a general method to decide the priority of LCA application through a logical procedure. First of all, evaluation categories were developed to decide priority of subject products(industrial groups). The evaluation categories consist of environment regulations related to subject product, LCA case studies, hazardous substances, etc. The subdivided database was constructed through researching and analyzing information about the selected evaluation categories. In addition, a questionnaire was conducted to reflect the opinions from academic and industrial circles. Based on the result of the questionnaire, each evaluation category and sub-evaluation category were weighed differently, and certain points were assigned to them. According to the method developed in this study, comparing industrial groups or products for prioriting will have its total score that is a sum of points assigned to each evaluation category. This results that an industrial group or product having higher score than the others becomes the subject to apply LCA.

초음속 유동장에 놓인 쐐기 주위의 유동 특성

신완순,신필권,이택상,김윤곤,박종호 忠南大學校 産業技術硏究所 1998 산업기술연구논문집 Vol.13 No.1

Theoretical analysis and experiment for supersonic flow around the wedges have been conducted. Wedges are being used as a means of measuring a flow direction, Mach No., a basic study of inlet or combustion chamber of ramjet and scramjet engine. We use a shock tunnel to get a supersonic flow conditions and schlieren system to visualize supersonic flow field around wedge. Numerical simulation is also conducted by Harten-Yee type 2nd-order Total Variable Diminishing(TVD) scheme and oblique shock theory. Comparison of calculated results with experimental data is in good agreement.

디스크형 캠기구 설계를 위한 순간속도중심설계법의 연구

신중호,김종수 國立 昌原大學校 産業技術硏究所 1994 産技硏論文集 Vol.8 No.-

As direct contact mechanisms, cam and follower mechanisms are used commonly in many machinery. Disk-typed cam mechanisms have 4 different types due to the different type of followers, such as reciprocating roller type, reciprocating flat-face type, oscillating roller type, and oscillating flat-face type. Depending on the shape of cam and type of follower, the motion of cam-follower mechanism is determined. Thus design procedure must be well defined for determining acculately the shape of cam corresponding to the given motion of follower. In this paper, an instant velocity center method is proposed. This method calculates the instant velocity centers of cam and follower in contact motion at any time. From geometric relationships on contact points of cam with follower, cam shape can be determined using the instant velocity centers. Also this paper presents 4 different cams for demonstration of the proposed design method and the results gives the exact solutions of cam design.

웨이브렛 계수 Zero Crossings를 이용한 영상의 잡음제거 및 압축

신재호,이용준,은종숙,이성우 동국대학교 산업기술연구원 1997 산업기술논문집 Vol.10 No.-

윤곽선이나 에지같은 영상 데이터의 중요한 성분들은 웨이브렛 계수의 zero crossings를 통해 검출할 수 있다. 이런 방법은 영상의 패턴 인식에 관한 연구에서 sharp variation points를 검출하는데 사용되었다. 웨이브렛 변환과 zero-crossings를 거쳐 국부 극치의 위치를 검출하는데 이 방법을 적용하여서 영상의 잡음제거에 사용하도록 개선하였다. 더욱이 영상 데이터에서 전체 영상의 픽셀과 정보를 저장하는 대신, 대부분의 중요한 성분을 효과적으로 몇몇 국부 극치값으로 압축하였다. 그 결과 새로 개선된 기법은 패턴 인식 분야에서만 아니라 높은 압축률의 잡음 제거에도 사용될 수 있다. The important image data components such as contours and edges could be detected by zero crossings of wavelet coefficient. This method has been used for the studies on pattern recognition of images to detect sharp variation points. We have applied it to detection of the position of local maxima through zero-crossings and wavelet transform, so that it is improved to be used for noise-eliminating of image. In addition it could compress the image data into a few of local maxima which held the most of important component efficiently without saving All image pixels and information. As the result, the newly improved method could be implemented not merely for the field of pattern recognition but for that of noise removal at the higher compression ratio.

詩와 遊戱 : 徐廷株論 An Essay on Suh,Jung-Joo

辛宗鎬 崇實語文學會 1997 崇實語文 Vol.13 No.-