해남 모이산 천열수 금은광상의 지구화학적 특성

문동혁,고상모,이길재,Moon, Dong-Hyeok,Koh, Sang-Mo,Lee, Gill-Jae 대한자원환경지질학회 2010 자원환경지질 Vol.43 No.5

전남 해남군 모이산 금광상에서 지구화학적 특성에 대한 연구를 수행하기 위하여 모이산 지표 및 갱내, 대산 지표에서 채취한 총 140개 시료에 대한 지구화학분석결과를 상관분석, 요인분석 그리고 군집분석 등 다변수 통계처리 하였다. 상관분석 결과, 금의 함량이 100 ppb 미만인 비광화대와 100 ppb 이상인 광화대에서 동시에 금과 높은 상관관계를 가지는 원소는 Ag, Cu, Bi, Te 등이며, 이는 연구지역에서 수반되는 함금 은 광석광물들(엘렉트럼, 실바나이트, 칼라버라이트 및 스퉤자이트)과 기타광석광물들(황동석, 텔룰로비스무타이트 및 비스무시나이트)의 산출과 일치된 결과로 인지된다. Mo은 비광화대(0.269)에서 보다 광화대(0.615)에서 상대적으로 높은 상관계수를 가지므로 금광화작용에 의해 그 함량이 강하게 지배되고 있는 것으로 해석된다. Mn, Cs, Fe, Se 등은 비광화대에서는 금과 정의 상관관계를 가지지만 광화대에서는 음의 상관관계를 가지므로 금광화작용 시 모암으로부터 용탈되는 원소군으로 해석된다. Sb은 광화대에서 금과 높은 상관성을 보이지만 비광화대에서는 음의 상관관계를 가지므로 금광화작용 시 부화되는 원소로 지시될 수 있다. 요인분석결과, 비광화대에서 금의 함량에 영향을 받는 요인군에 속하는 원소는 Se, Ag, Cs, Te 등이며 이들은 연구지역 내 비광화대에서 금의 존재 여부를 알려줄 수 있는 원소로 해석될 수 있다. 반면 광화대에서는 Mo과 Te 등이 강하게 금광화작용의 여부를 지시해 주며, 금과 함께 수반되는 은광화작용의 여부를 지시해 줄 수 있는 원소는 Sb과 Cu 등으로 해석된다. 군집분석 결과 비광화대에서 Cd-Zn-Pb-S, Bi-Fe-Cu-Mn, Se-Te-Au-Cs-Ag, As-Sb-Ba 등이 유사한 거동을 보이는 원소군으로 나타나는 반면, 광화대에서는 Cd-Zn-Mn-Pb, Fe-S-Se, As-Bi-Cs, Ag-Sb-Cu, Au-Te-Mo 등이 유사한 거동을 보여주는 원소군으로 나타난다. 이상과 같은 지구화학분석 자료의 다변수 통계처리를 이용하여 금광화대와 비광화대의 산출광물의 거동 및 지구화학적 특성 차이의 비교가 가능하므로 추후 이러한 방법이 이와 유사한 유형의 광상탐사에 유용한 방법으로 적용될 수 있을 것으로 기대된다. Geochemical characteristics of the Moisan epithermal gold-silver deposit with total 140 samples in Haenam area, Jeollanamdo were studied by using multivariate statistical analysis (correlation analysis, factor analysis and cluster analysis). The correlation analysis reveals that Ag, Cu, Bi, Te are highly correlated with Au in the both non-mineralized and mineralized zone. It is resulted from the presence of Au-Ag bearing minerals (electrum, sylvanite, calaverite and stuezite) and non Au-Ag containing minerals (chalcopyrite, tellurobismuthite and bismuthinite). Mo shows relatively much higher correlation at the mineralized zone (0.615) than non-mineralized zone (0.269) which implies Mo content is strongly affected by Au-mineralization. While Mn, Cs, Fe, Se correlated with Au at the nonmineralized zone, they have negative correlation at the mineralized zone. Therefore, they seem to be eluviated elements from the host rock during gold mineralization. Sb is enriched during the gold mineralization showing high correlation at the mineralized zone and negative correlation at the non-mineralized zone. According to the factor analysis, Se, Ag, Cs, Te are the indicators of gold mineralization presence due to the strong affection of gold content in the non-mineralized zone. In the mineralized zone, on the other hand, Mo, Te and Sb, Cu are the indicators of gold and silver mineralization, respectively. While the cluster analysis reveals that Cd-Zn-Pb-S, Bi-Fe-Cu-Mn, Se-Te-Au-Cs-Ag, As-Sb-Ba are the similar behavior elements groups in the non-mineralized zone, Cd-Zn-Mn-Pb, Fe-S-Se, As-Bi-Cs, Ag-Sb-Cu, Au-Te-Mo are the similar behavior elements groups in the mineralized zone. Using multivariate statistical analysis as mentioned above makes it possible to compare the behavior of presented minerals and difference of geochemical characteristics between mineralized and non-mineralized zone. Therefore, it will be expected a useful tool on the similar type of mining exploration.

SHS 공정에 의해 제조된 Mo_xW_1-xSi₂ 발열체의 열화메커니즘

이동원,이상헌,김용남,이성철,구상모,오종민,Lee, Dong-Won,Lee, Sang-Hun,Kim, Yong-Nam,Lee, Sung-Chul,Koo, Sang-Mo,Oh, Jong-Min 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.10

The degradation mechanism of $Mo_xW_{1-x}Si_2$ ultrahigh-temperature heating elements fabricated by self-propagating high-temperature synthesiswas investigated. The $Mo_xW_{1-x}Si_2$ specimens (with and without post-annealing) were subjected to ADTs (accelerated degradation tests) at temperatures up to $1,700^{\circ}C$ at heating rates of 3, 4, 5, 7, and $14^{\circ}C/min$. The surface loads of all the specimen heaters were increased with the increase in the target temperature. For the $Mo_xW_{1-x}Si_2$ specimens without annealing, many pores and secondary-phase particles were observed in the microstructure; the surface load increased to $23.9W/cm^2$ at $1,700^{\circ}C$, while the bending strength drastically reduced to 242 MPa. In contrast, the $Mo_xW_{1-x}Si_2$ specimens after post-annealing retained $single-Mo_xW_{1-x}Si_2$ phases and showed superior durability after the ADT. Consequently, it is thought that the formation of microcracks and coarse secondary phases during the ADT are the main causes for the degraded performance of the $Mo_xW_{1-x}Si_2$ heating elements without post-annealing.

Effect of post annealing on the microstructure, mechanical properties, and failure of Mo_xW_1-xSi₂ heaters produced by self-propagating high-temperature synthesis

Cho, Myung-Yeon,Lee, Sung-Chul,Park, Chulhwan,Lee, Daeseok,Koo, Sang-Mo,Moon, Kyoung-Sook,Lee, Dong-Won,Oh, Jong-Min Elsevier 2019 INTERMETALLICS Vol.110 No.-

<P><B>Abstract</B></P> <P>High-performance tungsten molybdenum disilicide (Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB>) heating elements were prepared using a self-propagating high temperature synthesis process. The effect of post annealing on the degradation behavior of the alloy was experimentally investigated. Increasing the attrition milling time up to 20 min during powder preparation resulted in Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB> heaters with the highest density, which increased the fracture strength compared to samples with shorter attrition times. Such samples were annealed and evaluated as heating elements using accelerated degradation tests and failure analysis in order to compare their structural characteristics and flexural strength with as-fabricated samples. The annealed Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB> heater showed a relatively dense structure with few pores and no secondary phases, apart from a SiO<SUB>2</SUB> layer. This favorable structure prevented bubble formation, which can result in fracturing of the heater, as revealed by evaluation at high temperatures with various heating rates. The flexural strength of the annealed specimen was 2.5-times higher than that of the as-fabricated specimen, which was attributed to removal of secondary phases during annealing. Failure time and surface load analyses were used to investigate the fracture mechanism of the Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB> heaters in detail at 1790 °C by quantifying bubble formation and the presence of secondary phases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Self-propagating high temperature synthesis of Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB> heaters demonstrated. </LI> <LI> Post-annealed Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB> heaters were highly dense, with good flexural strength. </LI> <LI> Bubble formation (the main cause of fracture) suppressed at ultra-high temperature (above 1700 °C). </LI> <LI> Surface load, failure time, and bubble formation used to study fracture mechanisms. </LI> </UL> </P>

The Moderating Role of Locus of Control on the Links between Experiential Motives and Online Game Loyalty

Dong‐,Mo Koo 한국산업경영학회 2008 한국산업경영학회 발표논문집 Vol.2008 No.4

Online games represent a burgeoning market sector with growth potential. The distinctive entertainment‐oriented features of such games provide various experiential motives for users. However, most previous studies have focused on the single dimensional affective motive of online game use. The multi‐dimensional affective motivational aspects of entertainment technologies have been relatively neglected. In addition, previous studies report inconsistent relationships between motives and online game usage. To fill these gaps in the literature, the present study proposes five experiential motives such as concentration, perceived enjoyment, escape, epistemic curiosity, and social affiliation as predictors of intention to play online games. Internal locus of control is also introduced as a moderator in the links between experiential motives and intention. The model is tested with the data from 576 current online game players and the data were gathered from online survey methodology. Structural equation model analysis confirms that three experiential motives with the exception of concentration and epistemic curiosity have a positive effect on intention. In addition, Chi square difference test confirms that internal locus of control has a moderating effect between the links from experiential values such as concentration, perceived enjoyment, and escape to intention. Implications are discussed in conclusion.

SHS 공정으로 제조된 Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si₂ 발열체의 가속수명시험과 고장분석

이동원(Dong-Won Lee),이상헌(Sang-Hun Lee),김용남(Yong-Nam Kim),이희수(Heesoo Lee),이성철(Sung-Chul Lee),구상모(Sang-Mo Koo),오종민(Jong-Min Oh) 한국전기전자학회 2017 전기전자학회논문지 Vol.21 No.3

고온자전합성과 후열처리 공정으로 MoxW1-xSi₂ 발열체를 제조하였다. MoxW1-xSi₂ 발열체의 신뢰성을 검증하기 위해 가속수명시험을 수행하였으며, 수명시간을 Minitab 프로그램으로 추정하였다. 또한, 가속수명시험 후의 MoxW1-xSi₂ 발열체의 고장분석을 전기적과 구조적 특성으로부터 수행하였다. 그 결과, MoxW1-xSi₂ 발열체의 지배적인 고장 유형은 발열체 내부의 크랙 형성과 SiO₂ 보호층의 박리임을 확인하였다. MoxW1-xSi₂ heaters were fabricated by self-propagating high-temperature synthesis (SHS) process and post sintering process. To validate the reliability of the MoxW1-xSi₂ heaters, the accelerated life test (ALT) was conducted, and then lifetime to MoxW1-xSi₂ heaters was estimated by using Minitab programs. Also, the failure analysis of MoxW1-xSi₂ heaters after ALT was performed through electrical and structural properties. As the results, it was confirmed that the dominant failure mode of MoxW1-xSi₂ heaters is the crack formation in heaters and the delamination of protective SiO₂ layers.

인삼고본환과 그 구성약물군의 항산화 효과

뢰영성 ( Yong Sung Loi ),권영모 ( Kwon Yeong Mo ),박종흠 ( Park Jong Heum ),박선동 ( Park Seon Dong ) 대한본초학회 2003 大韓本草學會誌 Vol.18 No.3

N/A objectives: Exposure to oxidant molecules can generate reactive oxigen species(R0S; for example, H₂O₂, O₂-, OH .). These free radicals can alter DNA, proteins and membrane phospholipids. ROS are responsible for aging and many diseases including cancer, neurodegenerative diseases and cardiovascular diseases. Thus, to prevent against celluar damages associated with oxidative stress, antioxidants are important and many research about antioxidants are being conducted over the world. methods: This study was performed to research the antioxidant activities of Insamgobonwhan(IG) and its component groups in vitro, so intended to know the possibility of Insamgobonwhan(1G) as drug which can prevent aging. The experimental group was divided into 4 groups: Imsamgobonwhan(IG), two dong-two jiwhang(IG-1; 麥門冬, 天門冬, 熱地黃, 生地黃), two dong(IG-2; 麥門冬, 天門冬) and two jiwhang(IG-3; 熱地黃, 生地黃). results: 1. All experimental groups had significant antioxidant activity in linoleic acid system on concentration dose--dependently in comparison with control group. But IG and IG-2 have more effect than IG-1 and IG-3 relatively. 2. DPPH radical scavenging experiment and inhibitory effect experiment on superoxide generation in xanthine-xanthine oxidase system showed that all experimental groups had a dose-dependent effect. But IG and IG--1 had more effect than IG-2 and IG-3. 3. Inhibitory effect experiment on superoxide generation induced by xanthine-xanthine oxidase system showed that all experimental groups had a dose-dependent effect. But IG and IG-1 had more effect than IG-2 and IG-3. 4. Inhibitory effect experiment on lipid peroxidation reaction in H₂O₂-Fe²system showed that all experimental groups had a dose--dependent effect. But IG and IG--1 had more effect than IG-2 and IG-3. 5. Experiment on lipid peroxidation removal effect showed that all experimental groups had a dose-dependent effect. But IG and IG-2 have more effect than IG-1 and IG-3. 6. Experiment on glutathion activity effect showed that all experimental groups had some effect. But each groups had no significant difference. 7. Experiment on catalase activity effect showed that all experimental groups had some effect. But each groups had no significant difference. conclusion: These results showed that IG has an antioxidant activity, so it seems to have some anti-aging effect. From comparisons of each experimental groups, IG`s antioxidant effect is likely to be associated with IG-1 mostly.

韓國河川의 流出率과 流出指標로서의 洪水直前 流量

金熙鍾,柳又秀,金佳鉉,申東守,韓健模,全裕燦 東亞大學校 大學院 1984 大學院論文集 Vol.9 No.-

This paper is a study on relation between run-off ratio and antecedent discharge, run-off ratio and antecedent discharge per unit area, antecedent discharge and antecedent precipitation, by the data from the five major river basins in Korea and the small river basins in Pusan. The Nak-Dong rivers(An-Dong upper stream) f=0.4780+0.0124 ln qA r=0.99 qA=0.3368e0.1101R r=0.99 f=0.5793+0.0146 ln(qA/A) r=0.99 The Nak-Dong rivers except Ga-song station f=0.2017-0.0840 ln qA r=0.75 f=0.7012+0.0750 ln(aA/A) r=0.71 The Han rivers f=-0.0035+01267 on qA r=0.75 f=1.1311+0.1263 ln(qA/A) r=0.71 L=302.9064-43.8490 ln qA r=0.84 The Geun rivers(Mu-sin Cheon) f=0.295+0.1823 ln qA r=0.93 f=0.8417+0.1823 ln(qA/A) r=0.93 L=40.0456+62.0346 ln qA r=0.94 The Yeong-san rivers f=0.3766+0.0598 ln qA r=0.79 f=0.8084+0.0599 ln(qA/A) r=0.79 The Seom-jin rivers f=-1.3875+0.6505 ln qA r=0.92 f=2.1633+0.3465 ln(qA/A) r=0.76 Small river basin in Pusan f=0.3635+0.1120 ln qA r=0.87

데페록사민 전처치가 토끼 심근경색 크기의 감소에 미치는 효과

양관모,오동렬,박승현,박규남,이원재,김형국,황두영,최승필,채장성 대한응급의학회 1998 대한응급의학회지 Vol.9 No.4

Background: Reperfusion of ischemic myocardium has been postulated to result in a specific oxygen radical mediated tissue injury. Iron may liberate during ischemia and we hypothesized that administration of the iron chelator, deferoxamine during ischemia would result in improved recovery after postischemic reperfusion. Purpose: To test whether iron-catalyzed processes contribute to myocardial necrosis during ischemia and reperfusion, deferoxamine was administered to block iron catalyzed hydroxyl radical formation in rabbits. Methods: Eleven rabbits were divided into two groups : control group (n=5) and deferoxamine pretreatment group (n=6). The left circumflex coronay artery was ligated for 30 minutes and reperfused for 180 minutes. Area at risk (AR) was measured by non-stained area with methylene blue injection into left atrium after left circumflex coronary artery ligation. Infarct size was measured by weighing after triphenyltetrazolium chloride staining. Heart rate was measured using electrocardiographic recording and systemic blood pressure was monitored by pressure transducer connected to the catheter in the left ventricle. Results: 1. There was no significant difference of heart rate and blood pressure in deferoxamine pretreatment group compared with control group. 2. There was significant decrease of serum iron concentration after continuous infusion of deferoxamine compared with serum iron concentration before ligation of coronary artery(P<0.05). 3. There was no significant difference of area at risk between control and deferoxamine pretreatment group. 4. Area at necrosis to area at risk was significantly reduced in deferoxamine pretreatment group compared with control group(P<0.05). The results suggest that deferoxamine infusion prior to coronary artery occlusion has a significant benefit in reducing infarct size in this model.

현장 실습의 필수 과목 도입을 위한 연구

서동신,윤동환,김경모 金烏工科大學校 1995 論文集 Vol.16 No.-

This paper describes the present situation of the curriculum on the elective subject field practice and characteristics of the subject which deserves to be a required subject in the viewpoints of many aspects from the industrial society requirements. We discussed the necessary method and the suggestions to the school authority to revise the curriculum to be required from elective. We also showed the effective way of operating the field practice with the considerations on its important property between the industrial firms and student careers, mentioning the engineering education suitable to adapt to the technologi1 society, and comparing the field practice environments in the universities of the developed countries on the intern system, fellowship, requisition research, civilian research activity, school-industry educational cooperation, etc. The school -industry educational cooperation was fully described from the past up to the present, and the better ways for our school to take steps on the changing conditions were classified with some opinions in the both sides of industry and school, and to the last the system and step to be carried were summarized with showing the standard model of the field practice based on the questionnaire on the engineering curriculum.

Bacillus sp. KCM-101에 의한 내열성 α-amylase의 생산 및 효소학적 성질

강상모,최유정,황윤영,이동희,권태종 건국대학교 산업기술연구원 2000 건국기술연구논문지 Vol.25 No.-

A strain isolated from soil was able to produce thermostable α-amylase. The strain (KC-101) was identification as Bacillus sp. Bacillus sp. KC-101 was treated NTG(N-methyl-nitro-nitrosoguanidine). The mutant KCM-101 increased α-amylase activity and decreased pretease activity. The condition for production, purification, and properties of α-amylase were investigated. α-Amylase production was maximized when was grown on soluble starch 2.0%, yeast extract 0.5%, K2HPO4 0.1% and MnCl2 0.02% for 24hrs at 37℃, and initial pH 7.0. The enzyme production was also increased by the addition of 0.01% Triton X-100. The enzyme was purified by ultrafiltration(MW 10,000), 80% ammonium sulfate precipitation, and Sephadex G-75 gel chromatography and it's yield 15.0%, The characteristics of purified α-amylase were as follow : MW 55,000, optimal pH and temperature were 7.0 and 95℃, respectively. The enzyme was activated by Ca++ and Mn++ ion but inhibited Co++, Cu++, Hg++, and Pb++ ion. The enzyme was stable at 95℃ and it's thermostability was greatly increased by the addition of Ca++. In kinetic studies, the Km value of α-amylase for soluble starch was 0.93mg/mL.