Effects of I- and W-Phases Under Identical Conditions on Microstructure and Mechanical Properties of As-Cast Mg–Zn–Y Alloys at Room and Elevated Temperatures

Young‑Gil Jung,Wonseok Yang,Jae Ik Hyun,Shae K. Kim,Hyunkyu Lim,Do Hyang Kim 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12

Three alloys (Mg–6Zn–1.2Y, Alloy I; Mg–3.65Zn–1.65Y, Alloy II; and Mg–4.3Zn–1.4Y, Alloy III) with same volume fractionand grain size were designed to evaluate the effects of the I-phase (Mg3Zn6Y) and W-phase (Mg3Zn3Y2), which are themajor phases in Mg–Zn–Y alloys, on the mechanical properties. The tensile strength of Alloy I with the I-phase at roomtemperature was the highest among the tested alloys because the coherent interface between the I-phase and the α-Mg phasewas more resistant to cracking than the incoherent interface between the W-phase and the α-Mg phase. A cross-sectionalmicrostructure analysis of a sample that was tensile-tested at 423 K revealed that the morphology of the I-phase remainedrelatively stable. In contrast, the W-phase was broken and fragmented during the tensile test at 423 K because it had higherbrittleness under the test conditions. Therefore, the tensile and creep properties of Alloy I at 423 K were better than thoseof Alloys II and III containing the W-phase. According to the results, the I-phase in the Mg-Zn-Y alloy was more beneficialto the mechanical properties at room temperature and 423 K than the W-phase.

영상 정보를 이용한 자율 주차 시스템에 관한 연구

김영민(Young-min Kim),강희정(Hee-jung Kang),방상우(Sang-woo Bang),임영도(Young-do Lim) 한국정보기술학회 2010 한국정보기술학회논문지 Vol.8 No.5

Generally parking of the vehicle only driver sight and in compliance with an experience comes to do the spatial security which is caused by with judging distance and the camera which are accurate the various sensor, but it in recent times is caused by with technical advancement and leads was possible, parking was quicker and safely there made be a possibility of doing. So about unmanned parking the research vehicle with technical advancement and in standard to be advanced from the side which is various comes. In this paper the parking sector from the public parking lot or the formation parking market is clear and importance in the space where the unmanned camera is established in the parking sector depends in real-time image value and is parks autonomously. The camera which is established in the parking sector guard and the vehicle of parking space, recognized the object with real-time image processing and the vehicle wheel track angle in compliance with a image data and presumed Fuzzy-control led and in the four-wheel mobile robot and parking a production value and got applied accomplished.

랜덤포레스트를 이용한 낙동강 본류의 남조류 발생 영향인자 분석

정우석(Jung, Woo Suk),김성은(Kim, Sung Eun),김영도(Kim, Young Do) 한국습지학회 2021 한국습지학회지 Vol.23 No.1

본 연구에서는 랜덤포레스트를 이용하여 8개 보 지점별 남조류 발생 주요 영향인자를 도출하고, 조류경보제 기반의범주형 예측모델을 개발하였다. 8개 보 지점의 랜덤포레스트의 변수 중요도를 살펴본 결과, 상류의 보 지점들은 남조류 발생에 있어 보 운영에 따른 영향을 직접적으로 받는 것으로 나타났다. 이는 효율적인 보 운영을 통한 남조류 관리가 가능할 수 있다는 것을 의미한다. 중류 구간은 DO와 E.C가 주요 영향인자로 도출되었다. 공간적으로 구미와 김천에 대규모 산업공단들이 밀집되어 있으며, 환경기초시설의 배출량이 큰 영향을 끼치는 구간이다. 따라서 폭염 및 가뭄 시기에 중류 유역에서 배출되는 환경기초시설의 방류는 본류의 E.C를 증가하게 하고 남조류 발생을 촉진 시키는것으로 나타났다. 중·하류에 위치한 보 지점들은 폭염 및 가뭄의 영향을 가장 많이 받는 지역으로 여름철 가뭄에 따른남조류 대발생에 대비하여 선제적인 관리가 필요한 지점으로 나타났다. 본 연구를 통해 지점별 남조류 발생 영향인자를 도출하였으며, 맞춤형 조류관리를 위한 정책적 의사결정의 기초자료로 제공될 수 있을 것으로 판단된다. In this study, the main influencing factors of the occurrence of cyanobacteria at each of the eight Multifunctional weirs were derived using a random forest, and a categorical prediction model based on a Algal bloom warning system was developed. As a result of examining the importance of variables in the random forest, it was found that the upstream points were directly affected by weir operation during the occurrence of cyanobacteria. This means that cyanobacteria can be managed through efficient security management. DO and E.C were indicated as major influencers in midstream. The midstream section is a section where large-scale industrial complexes such as Gumi and Gimcheon are concentrated as well as the emissions of basic environmental facilities have a great influence. During the period of heatwave and drought, E.C increases along with the discharge of environmental facilities discharged from the basin, which promotes the outbreak of cyanobacteria. Those monitoring sites located in the middle and lower streams are areas that are most affected by heat waves and droughts, and therefore require preemptive management in preparation for the outbreak of cyanobacteria caused by drought in summer. Through this study, the characteristics of cyanobacteria at each point were analyzed. It can provide basic data for policy decision-making for customized cyanobacteria management

대동맥 협착증과 동반된 출혈성 위장관 동정맥 기형에서 Estrogen-Progesterone 치료 1예

김도연,김화정,김효정,남준식,박수영,박영미,신정은,주미순,황민규,정혜경,손혜영,이선영,이한주 大韓消化器內視鏡學會 1999 Clinical Endoscopy Vol.19 No.부록2

만성두통환자에 대한 침치료가 심박변이도에 미치는 영향

정인태,이상훈,김수영,차남현,김건식,이두익,이재동,임사비나,이윤호,최도영 EAST-WEST MEDICAL RESEARCH INSTITUTE KYUNG HEE UNI 2005 東西醫學硏究所 論文集 Vol.2005 No.-

Objective : The purpose of this study was to assess the effect of acupuncture treatment for chronic headache patients using power spectrum analysis of the heart rate variability(HRV). Methods : 15 clinical experiment participants were gathered and through a questionnaire patients who experienced headache for more than 4 hours a day and more than 15 days per month were qualified as Chronic Headache patients. Treatment was applied 2 times a weeks for 8 weeks. The acupoints, GV20, HN23, ST8, HN46, TE17, GB20, LI20, LI11, LI14, ST36, and LR3 were stimulated for 20 minutes. The effects of acupuncture treatment were analyzed using power spectrum analysis of the HRV, HRV was recorded before and after acupuncture treatment. Results : HRV before and after treatment was compared after 8 weeks of acupuncture treatment. Increase in mean values of SDNN and RMSSD were observed but the increases were not statistically significants. Increase in mean values of TP, LF and HF were observed but, the increase was significant(p<0.05) only in TP. Conclusions : The results suggest that acupuncture treatment on chronic headache patients can increase the activity of autonomic nervous system. Further use of HRV for quantitative analysis of acupuncture treatment on autonomic nervous system related symptoms is suggested.

복합구조물의 파괴에 관한 치수효과의 중요성

정영화,김경진,원치문,심도식 江原大學校 産業技術硏究所 1995 産業技術硏究 Vol.15 No.-

In this paper, the importance of the size effects on the strength ratio is demonstrated by numerical results. The rate of decrease of tensile strength is for glass fiber, based on the experience of a composite manufacturing specialist. For other material, similar procedure may be used until detailed test result on such material is available. The strength criteria used is that of Tsai-Wu for stress space. The factors influencing the ratio are, reducing the tensile strength alone or both tensile and compression strengths, selection of the normalized interaction term, that is, the generalized Von Mises criterion or the Hill's criterion, and the status of applied stresses. Some of the numerical results are presented for a guideline for the furture study.

만성두통환자에 대한 동서협진의 임상적 연구

정인태,이상훈,김수영,차남현,김건식,이두익,이재동,임사비나,이윤호,최도영 EAST-WEST MEDICAL RESEARCH INSTITUTE KYUNG HEE UNI 2005 東西醫學硏究所 論文集 Vol.2005 No.-

Objective : Because the cause and etiology of chronic headache are not yet fully explained, the treatment of this symptom is not simple. In order to study the effectiveness East-West pain treatment on chronic headache, we evaluated its effect of pain alleviation and quality of life improvement on chronic headache patients who were treated with nerve block and acupuncture, and only acupuncture for eight weeks. Methods : 92 clinical experiment participants were gathered and through a questionnaire patients who experienced headache for more than 4 hours a day and more than 15 days per month were qualified as chronic headache patients. The qualified patients were classified into two groups, nerve block and acupuncture group(EW group, n=49) and acupuncture group(E group, n=43). Treatment was applied 2 times a weeks for 8 weeks. The acupoints, GV20, HN23, ST8, HN46, TE17, GB20, LI20, LI11, LI14, ST36, and LR3 were stimulated for 20 minutes. The effects of two groups were analyzed using VAS scores and BPI(Brief Pain Inventory). Results : The VAS and BPI after four weeks of treatment showed significant improvement among two but differences between the three groups was statistically insignificant. The VAS and BPI of the EW group after eight weeks of treatment showed statistically significant improvement compared to the other two groups. Conclusion : The pain treatment for chronic headache might be contributed to improvement of quality of life as well as alleviation of pain of chronic headache patients. It was suggested that the West pain treatment in combination with East pain treatment might be an useful modality to improve the pain and quality of life in chronic headache patients.

후막 전계발광소자(Electroluminescence)의 제조와 발광특성

정영호,김병권,박조용,명광식,Khatkar, S.P.,Liang, Yujun,한상도 경북대학교 센서기술연구소 2002 센서技術學術大會論文集 Vol.13 No.1

충격기법을 이용한 볼트결합 구조부의 진동해석

鄭泳都,朴世蔓,朴明均 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-

Abstract - There are various methods to join mechanical structures together. They typically include welding, mechanical joints by bolts and other processes depending on specific needs. Analyses of joints in the mechanical structures are essential in understanding the dynamic characteristics of the structures. In this research an impulse technique is applies to investigate the dynamic behavior of joints produced by bolts. The length of overlap in the joints was varied as the number of the bolts in the joints was changed. Also, the torque applied to the bolts were adjusted. Resonance frequencies were determined for the joints to evaluate the relationship between the increase in the applied torque and the increase in the number of bolts used in the joints. The results have demonstrated that the resonance frequencies of the joints increase with the increasing torque.

탄성반력의 영향에 따른 직교 이방성 복합판의 고유 진동 해석

정영화,심도식,김경진,이세진 江原大學校 産業技術硏究所 1997 産業技術硏究 Vol.17 No.-

In this paper, the result of application of vibration method to the orthotropic plates with free edges supported on elastic foundation and with a pair of opposite edges under axial forces is presented. Such plates represent the concrete highway slab and hybrid composite pavement of bridges. The reinforced concrete slab can be assumed as a special orthotropic plate, as a close approximation. The highway slab is supported on elastic foundation, with free boundaries. Sometimes, the pair of edges perpendicular to the traffic direction amy be subject to the axial forces. The plate is subject to the concentrated load/loads, in the form of traffic loads, or the test equipments. Finite difference method is used to obtain the deflection influence surfaces needed for vibration analysis. The influence of the modulus of the foundation, the aspect ration of the plate, and the magnitudes of the axial forces and the concentrated attached mass on the plate, under the natural frequency is thoroughly studied.