Evaluation of Hot Deformation and Dynamic Recrystallization Behaviors of Advanced Reduced-Activated Alloy (ARAA)

Sang‑Wook Kim,Hyeon‑Woo Son,Taek‑Kyun Jung,Young‑Bum Chun,Yi‑Hyun Park,Ji‑Woon Lee,Soong‑Keun Hyun 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4

The hot deformation behavior of advanced reduced-activation alloy (ARAA) was investigated using hot torsion tests. Thefl ow stress decreased as deformation temperature increased and as strain rate decreased. The fl ow behavior demonstratedthe typical dynamic recrystallization (DRX). Based on the constitutive analysis of peak stress, the activation energy for hotdeformation was found to be 330.3 kJ mol −1 . Peak stress was analyzed as a function of the Zener–Hollomon parameter, andcalculated and experimental values were in good agreement. A DRX kinetic model for ARAA was derived with deformationconditions based on the Avrami-type model. It was confi rmed that the volume fraction of dynamically recrystallized grainsincreased as deformation temperature increased and as strain rate decreased. The necklace structure and grain boundarybulging were observed in the deformed microstructure of ARAA. The suggested DRX mechanism for ARAA during hotworking is discontinuous DRX.

機械加工品의 最適加工速度에 關한 硏究

成煥泰,吳澤烈,吳煥燮 慶熙大學校 1980 論文集 Vol.10 No.-

In this study, the optimum mathematical models were made in order to derive Optimum Machining speed which is due to be established in the production of each manufactures as an important parameter based upon the cutting speed, in case of making manufactures of multi-kinds into unit-production processing. The economical optimum cutting speed has been set up by using the above phenomenon as a proper system, and the results from the comparative analysis between the above model & the actual cutting work data, are summarized as follows. (1) The mathematical models for the optimum machining speed are derived into the expressions (23), (24), (25), (26), (27), (28), (29). (2) The basic expressions of the optimum machining speed are derived into (32), (34), (36), (37), (39), (40), (41), (44), for the purpose of each estimation of the maximum efficiency standard, the minimum cost standard and the maximum profits rate standard. (3) The example of setting up the optimum cutting speed of multi-kinds manufacturing production was formulated, and the experimental theoretical values were known to be in the same range as a result of the comparative study between the cutting speed obtained by the cutting test & the optimum cutting speed calculated by the theoretical expressions.

태양광 발전시스템을 위한 계통 연계형 PWM 인버터의 변조지연 보상

성낙규,한경희,강승욱,이승환,유택빈 明知大學校 産業技術硏究所 1995 産業技術硏究所論文集 Vol.14 No.-

Since the residential load is an AC load, while the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell and must provide the sinusoidal wave current and voltage, at unity power factor in the case of driving to interact with utility line. PWM modulator must do stable modulation even though it contains the disturbance like a distortion and noise, and it needs compensation method, because there is a timing interval between sampling points and carrier waves, while the synchronous signal is controlled by the micro processor. In this paper, we maximaze output of solar cells which is propotional to variation of insolation, using single phase PWM voltage source inverter, and we can drive in high power factor with utility line by control and compensation method which is concerned with synchronous signal distortion and modulation delay, using low pass filter and phase shifter.

월악산 지역의 리기다소나무 조림지에서 간벌후의 갱신 특성

정택상,권기철,김홍은 忠北大學校 農業科學硏究所 2002 農業科學硏究 Vol.19 No.-

The objective of this study was to examine the growth and regeneration patterns of hardwood saplings after thinning of Pinus rigida planted at Mt Worak After thinning of P. rigida, r-selection species such as Rubus crataegifolius B, Lespedeza maximowiczii C, Aralia elata var canescen N., Rubus oldham M and Quercus spp were mainly appeared Regarding to numbers of young trees appearance, Q. mongolica F, Q acutissima C, Q. serrata T and Q variabilis B1 were appeared respectively At the study area after thinning, Q. mongolica F was regenerated by sprouts on the other hands, Q. acutissima C, Q serrata T and Q. variabilis B1 were regenerated by seedlings. The results of this study indicated that Q mongolica F tended to dominate as a natural regenerated species after thinning of the P. rigida. At the humid area, Q serrala T tended to dominate. While, at the dry area, Q. mongolica F. tended to dominate. In the case of Q. variabilis B1, no significant influence was found due to small number of population.

ATM망의 가상경로상에서 Threshold를 이용한 효율적인 대역관리

김상철,고승일,고성택,김경식,김경연 濟州大學校 情報通信硏究所 1999 情報通信硏究所論文集 Vol.2 No.-

Effective bandwidth allocation is desirable to control the ATM traffic. It should provide high fairness and utilization for different kinds of services in call admission. Complete bandwidth sharing is efficient for utilization of bandwidth but not efficient for fairness of call admission. Complete bandwidth partitioning is efficient for fairness but not efficient for utilization. We propose a new CST(Complete Sharing with Threshold) algorithm using threshold in a VP to improve fairness and utilization. Using CST algorithm. the system performance is improved by 1.4% compared with the RSC(Reserved Sharing with Common pool) algorithm.

直感을 응용한 企業經營戰略(Ⅱ)

李相俊,徐佑澤 홍익대학교 동북아연구소 2002 東北亞硏究 Vol.6 No.-

It is said the 21st century is so-called the era of Fs, which stand for Feeling, Fiction and Female. One of the common characteristics of these 3 Fs is that, according to the theories of physiology, they are related to the work of the right part of brain rather than the opposite. This means the masculine world where the physical and realistic power has been domineering is being replaced by the feminine one where more emotional and metaphysical power is regarded to be superior. That is to say, the dominant trend that the society of left-brain is being moved to the society of right-brain is expected to emerge in this 21st century. And This trend is also expected to bring some changes to the corporate management by developing new products with the focus on sensationalism and metaphysics and by widening the range of services that a corporate renders. Therefore it is underlined that a different approach to the management by sensibility, which has been underestimated compared to the conventional management method, is needed along with the efforts to find out its practical applications. However, it must be noted that these two different management methods are not contending each other. A consolidated management strategy that maximizes the strengths of those two management methods with which we would survive this new management strategy by paying more attention to the intuitive power. To accomplish this, each corporation must establish its own program reflecting its situations, circumstances and abilities.

建設現場의 電氣設備安全에 관한 調査 硏究

林晩澤,鄭集汶,朴星夏,李平圭 朝鮮大學校 建設技術硏究所 1999 建設技術硏究 Vol.19 No.2

The purpose of this study is to consider a plan to improve the peoples' electrical safety consciousness by investigating the causal factors and issues of electrical safety accidents at construction fields and to offer effective preventive measures against electrical accidents. The conditions of installation, maintenance, and management of electrical equipment by shape, hydroelectric voltage, and area of construction fields in Kwangju and the Chonnam region were investigated. Thirty- two construction fields were chosen, and their conditions of safety management and installation of high- voltage and subordinate equipment were investigated. The electrical safety consciousness of 157 workers at the fields was surveyed. The main constant of the investigation was the conditions for the installation, maintenance, and management of hydroelectric equipment, the installation and management of electric wiring, the use, of mobile electrical and portable type apparatus, the possession and management of electrical safety devices, the case investigation of electric shocks, and the safety consciousness of the workers at the fields.

成長과 變化에 대응하는 캠퍼스 計劃에 관한 기초적 硏究

강성택,조용수 동아대학교 건설기술연구소 1999 硏究報告 Vol.22 No.2

This study aims at providing a fundamental guide for the growth of university and extension of its facilities. Growth types of campuses were studied and analysed by theoretical and empirical research on six sample universities. Finally, some planning guides for organic growth and spatial composition of campus facilities were proposed for the design of campus masterplan.

당뇨병 백서의 간세포에서 Glucokinase 활성도 및 유전자 발현에 대한 인슐린의 영향

강성이,팽정령,서광식,안규정,우정택,김성운,양인명,김진우,김영설,김광원,최영길 경희대학교 유전공학연구소 1993 遺傳工學論文集 Vol.5 No.-

목적 당대사의 조절 상태에 따른 생체 변화를 분자 수준에서 이해하고자 식이 조건을 달리한 정상 백서와 화학적으로 유도된 당뇨병 백서의 간조직에서 혈당수준과 인슐린치료 정도에 따라 나타나는 글루코키나제 활성도 및 유전자 발현을 분석하였다. 방법 스트렙토조토신 정맥투여 후 당뇨병의 유발을 확인하고, 인슐린을 1일 3회 3일간 복강내로 투여하여 상태를 안정시킨 후, 인슐린 투여군은 인슐린 투여 6시간이내에 그리고 인슐린 비투여군은 24시간 후 단두하여 채혈하고 복강을 열어 간조직을 채취하였다. 채취한 간조직에서 글루코키나제 활성도는 인산화된 포도당에서 NADH의 형성을 형광분광계로 측정하였으며, 글루코키나제 유전자 mRNA발현은 Northern 분석법을 이용하였다. 성적 정상 백서에서 공복상태와 식이를 섭취한 경우에 간조직의 글루코키나제 효소의 활성은 차이가 없었으나, 글루코키나제 유전자 mRNA 발현은 증가되었다. 당뇨병이 유발된 백서의 간조직에서 글루코키나제 효소의 활성 및 글루코키나제 유전자의 mRNA 발현은 정상 백서에 비하여 낮았다. 인슐린 투쳐 후 글루코키나제 효소의 활성 및 글루코키나제 유전자의 mRNA 발현이 증가되었고, 특히 혈당이 정상화된 경우에서 글루코키나제 유전자의 mRNA 발현이 증가도었다. 결론 인슐린에 의한 간조직에서 글루코키나제 효소의 활성 및 글루코키나제 유전자의 mRNA을 증가를 볼수 있었다. 당뇨병 백서에서 인슐린 투여 후에 혈당조절이 안된 경우 간조직의 글루코키나제 유전자의 mRNA 발현이 증가가 없는 것으로 보아 글루코키나제 mRNA의 발현에는 인슐린 이외의 다른 요소가 관여할 것으로 생각된다. The liver-specific hexokinase isoenzyme, referred to as glucokinase, is thought to play a key reglulatory role in hepatic glucose metabolism. The glucokinase gene is, therefore, of interest both because of its tissue-specific expression and because of the several regulatory processes that can be analyzed. The level of hepatic glucokinase activity appears to be determined essentially by regulation of the rate of enzyme synthesis, with insulin playing a leading role as an inducer. We investigated the role of insulin for the induction of glucokinase in the liver of diabetic rats. Experimental diabetes was induced by injection of streptozotocin 7 days before the experiment. Regular insulin was given by three days intraperitoneal injection at 8-h interval. The glucokinase mRNA in the liver was estimated by Nothern blot assay, as well as by fluorometric enzyme activity assay. Glucokinase activity was not reduced in the liver of normal fasting rats as compared to normal fed rats. And glucokinase activity was reduced in the liver of diabetic rats as compared to normal rats. In diabetic rats treated with insulin, glucokinase enzyme activity were increased. But glucokinase mRNA expression was only increased in normoglycemic diabetic rat with treated with insulin as compared to hyperglycemic rat. These data indicate that insulin stimulates hepatic glucokinase enzyme activity and mRNA expression. But other hormonal or metabolic factors may be contribute to regulation of glucokinase mRNA expression.

물체-검출기 동기회전 방식의 X-선 단층영상시스템 설계 및 성능개선에 관한 연구

강성택,조형석,노병옥 제어·자동화·시스템공학회 1999 제어·자동화·시스템공학논문지 Vol.5 No.-

This paper describes my experiences in delivering a 3-year of psychological service to the Korean National Archery Team(1996-1998). The process of developing psychological skills training programs(PSTP) over a 3-year period is outlined. The contents of PSTP are explained and the importance of full cooperation from coaches, sport organization, and the ethics of the coach is discussed as well.