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.

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

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

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.

한센병 환자의 족저궤양과 최대 족저압력과의 관계

정도영,박경희,이강성 한국전문물리치료학회 2002 한국전문물리치료학회지 Vol.9 No.1

Foot ulceration results in substantial morbidity in patients with peripheral neuropathy. The purpose of this study was to find the relationship of plantar foot pressures during walking to plantar ulceration in patients with Hansen's disease. The subjects were recuruited from two Welfare Clinic for Hansen's disease in Wonju and Uiwang city. Ten subjects (5 females, 5 males) with plantar ulceration and a mean age of 63 years were evaluated in this study. The mean duration of Hansen's disease in these subjects was 30 years. Plantar pressures were measured during self-selected comfortable walking speed by using MatScan system. Three subjects had plantar ulceration under the first metatarsal head. Five subjects had plantar ulceration under the second and third metatarsal head. Two subjects had plantar ulcers under the fifth metatarsal head. Eight of 10 subjects had plantar ulceration at highest pressure point that measured during walking. This result suggests that the abnormal high plantar pressure could be related factor to plantar ulceration in patients with Hansen's disease. Also the foot pressure measurement may be useful to evaluate the risk of plantar ulceration in patients with Hansen's disease.

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.

동결온도가 진공포장 동결육의 품질에 미치는 영향

정인철,김도완,문귀임,강세주,김기영,문윤희 한국식품영양학회 1998 韓國食品營養學會誌 Vol.11 No.4

본 연구는 진공포장 동결육의 품질에 미치는 영향을 검토하기 위하여 수행하였다. 해동드립은 -3℃와 -20℃ 동결이 60일째 각각 5.23% 및 5.17%로 동결기간이 경과함에 따라 현저하게 증가하였다. 가열감량은 water bath와 pan에서 가열한 것이 모두 동결초기보다 동결기간이 경과함에 따라 현저하게 증가하였다. 그러나 -3℃와 -20℃ 사이에는 현저한 차이가 없었다. 염용성 단백질의 추출성은 동결기간이 지남에 따라 감소하였고, -20℃ 동결이 -3℃보다 추출성이 더 높았다. 수용성 단백질의 추출성은 동결기간이 경과하면서 증가하였고 -3℃ 동결이 -20℃보다 현저하게 높았다. 그리고 L, a 및 b값은 저장초기가 동결저장 중보다 높다. Myoglobin의 변성율은 -3℃ 동결이 -20℃보다 비교적 높게 나타났는데, -3℃ 동결의 15일째가 96.0%로 가장 높게 나타났다. 전단력가는 동결저장 중 현저한 변화가 없었고, 근원섬유의 소편화도는 동결초기보다 동결저장이 더 높았지만 동결저장 중에는 변화가 없었다. pH는 -3℃와 -20℃ 동결저장 모두 45일까지 감소하다가 그 이후에는 증가하는 경향이었다. This study was carried out to investigate the effects of freezing temperature on quality of vacuum packaging freezed beef. In case of thaw drip loss, the freezing of -3℃ and -20℃ were 5.23% and 5.17% to 60 days respectively, were increased significantly during freezing. The cooking loss of water bath and pan were increased significantly during freezing than the beginning of freezing, but were no different between -3℃ and -20℃. The salt soluble protein extractability was decreased during freezing, the -20℃ freezing was higher than -3℃ freezing. The water soluble protein extractability was increased during freezing, the -3℃ freezing was higher than -20℃ freezing. The L, a and b value of the beginning of freezing higher than during freezing. The myoglobin denatured percentage of the -3℃ freezing was higher than -20℃ freezing, the 15 days storage of -3℃ freezing was highest to 96%. The shear force value was not change during freezing, the myofibrillar fragmentation index during freezing was higher than the beginning of freezing, but was not change during freezing. The pH was decreased to freezing 45 days, after that increased.

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.

회전자 구조에 따른 SRM의 토오크 특성해석

정도영,이상호,서진우,오홍석,최경호 三陟大學校 1997 論文集 Vol.30 No.1

The switched reluctance motor(SRM) has a simple rotor construction with no windings. It also has simple concentrated windings on the stator. Thus, it is expected to be a lower cost machine to manufacture than the squirrel cage induction motor. This paper presents an advanced rotor structure type, well-round rotor type in SRM. To design the improved SRM we have used FEM and studied and compared with each other. The static torque, instantaneous torque and average torque are more improved than that of typical rotor type which has been a lot of used for SRM.

만성두통환자에 대한 아로마침의 임상적 연구

정인태,김수영,김건식,이두익,이재동,이윤호,최도영 WHO COLLABORATING CENTRE FOR TRADITIONAL MEDICINE 2004 東西醫學硏究所 論文集 Vol.2004 No.-

Objective : Because the cause and etiology of chronic headache is not yet fully explained, the treatment of this symptom is not simple. This study compares the effects of aroma acupuncture and normal acupuncture applied an chronic headache patients, in order to establish a primary data for further studier of new treatments and developments of new practical acupunctures. Methods : 38 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 in to two groups, aroma acupuncture group(Aroma AT group, n=23) and normal acupuncture group(AT group, n=15). 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 in both the groups. The effects of both groups were analyzed using VAS scores and BPI(Brief Pain Inventory). Results : The VAS pain scores improved significantly in both groups. The decrease rate was larger in the Aroma AT group(p<0.05). The BPI scores for the both groups also decrease. The improvement in the Aroma AT group was larger(p<0.05). Conclusion : Aroma acupuncture applied on chronic headache patients showed effects of relieving pain, improving general activities, changing the mood, and improving sleeping behaviors. These effects were analyzed using VAS scores and BPI. The Aroma AT group showed significant changes of VAS and BPI compared to the AT group, suggesting that this new practical acupuncture is very effective when treating chronic headaches. Further researches are needed to evaluate the distinct functional mechanism of aroma acupuncture, but this study is meaningful in the sense that it will act as a fundamental study to build on.