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Effect of Highly Pressurized Hydrogen Gas Charging on the Hydrogen Embrittlement of API X70 Steel
Dong-Su Bae,Chi-Eun Sung1,Hyun-Ju Bang,Sang-Pill Lee,Jin-Kyung Lee,In-Soo Son,조영래,Un-Bong Baek,Seung-HoonNahm 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.4
During the use of API X70 steel as a pipeline structural material for the transportation of natural gas,hydrogen embrittlement can occur due to the hydrogen contained in natural gas. The aim of this study is toinvestigate the effects of the hydrogen content under high-pressure hydrogen gas conditions on the hydrogenembrittlement of air-cooled API X70 steel. The air-cooled API X70 steel was manufactured by hot rollingand was then air-cooled to room temperature. Tensile test specimens were held for 0 h, 1000 h, and 2000 hwithin a pressure vessel filled with 100% hydrogen gas at a gas pressure of 10 MPa, with the tensile teststhen performed at room temperature. The microstructure of the API X70 steel consists of coarse polygonalferrite, coarse pearlite, and fine acicular ferrite. The yield and tensile strength increased and elongationdecreased considerably after a holding time of 2000 h compared to those of 0 h and 1000 h within the pressurevessel. The morphology of the fracture surface changed from ductile to brittle upon hydrogen gas charging. Secondary cracks were observed in both of the hydrogen-gas-charged specimens. No external cracks wereformed on the surface of the tensile-tested specimen with a 0 h holding time; however, many external crackswere observed on the specimen surface subjected to hydrogen gas charging.
이기환,구광호,이상용,이규용,유언호,김종숙 ( Ki Whan Lee,Kwang Hoo Koo,Sang Yong Lee,Kyu Yong Lee,Un Ho Ryoo,Chong Sook Kim ) 대한소화기학회 1974 대한소화기학회지 Vol.6 No.1
The measurements of sium amylase and urine amylase for 2-1 and 2 hrs were caried ou normal perso,-s, 118 pat;:enls vith disardei s in the upp r alimentary tract, 184 patie.,ts v, ith h;le- cystopathy and 26 patients ivith acute pancreatitis. The follosving rc.su1ts were drawn: In the normal prsons, the average determination of serum amylas was 5-l. I L 21, 9. Units ' 100 m]. It shov;ed no difference by sex and age. 2 The frequezcy manifesting raise of serum amylase (the value higher than mean+2S.I),,, v,as 5 ] y in the patients with the upper G.I. Disorders, an<l 6, l,jj in the patients of chiIccys'.:>p.ithy v, ith normal features in cholecys.ograms. It, however, showed 2S. 7, of frequeny appeaiing nis:.. of serv,m an.ylase in the patients of cholecystopathy with abnorrnalities in roentgenographic exa!ii- ;iations indicating a mean value of 86. 4 31. 67 units,'l0(l ml. 3, The determination of s rum amylase in the pat,ents of acute pancreatitis was 12a. ] un!ts,'100 ml on the initial day, and it showed ahrupt diminution thereafter. 4. Each dete:mination of urine amylase for 24 and 2 hnurs was 1394. 3 .867. 43 and 15 4 -(j;, Hi units in the normal pers1ns, but there was no significant shift in the group of the uppr:.;- G,I disorders, and a little raise in the group of cholecystopathy. In the group of acute panc:eatili:., ii showed marked rais of urine amylas, ,6562, 9---4526, 3<J units for 24 hours on the se ond cia o!' ailment), revealins: subs quent gradual cle rease, (30i;>. 9 l 1927. 92 units on the sexth day',. It must b emphasized that in picture of urine amylase should be a great help for c!iagnos!.ng tli. Conditions.
한국형발사체 3단 과산화수소 추력기시스템 제어장치 아날로그 데이터 취득 스케줄링 변경을 통한 노이즈 측정오류 개선
이상현(Sang-Hyun Lee),송우근(Woo-Keun Song),오현명(Hyun-Myung Oh),이정운(Jung-Un Lee),이종철(Jong-Cheol Lee),박상준(Sang-Joon Park),이상빈(Sang-Bin Lee),이희중(Hee-Joong Lee),오상관(Sang-Gwan Oh),민병주(Byeong-Joo Min) 한국항공우주학회 2020 한국항공우주학회 학술발표회 논문집 Vol.2020 No.11
A New Phenylpropane Glycoside from the Rhizome of Sparganium stoloniferum
Lee, Seung-Young,Choi, Sang-Un,Lee, Jei-Hyun,Lee, Dong-Ung,Lee, Kang-Ro 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.4
The purification of the MeOH extract from the rhizome of Sparganium stoloniferum Buch.-Hamil. (Sparganiaceae) using column chromatography furnished one new phenylpropanoid glycoside (7) and known phenolic compounds (1-6, and 8-13). The structural elucidation of 7 was based on 1D- and 2D-NMR spectroscopic data analysis to be ${\beta}$-D-(6-O-trans-feruloyl) fructofuranosyl-${\alpha}$-D-O-glucopyranoside. Compounds 1-6, and 8-13 were elucidated by spectroscopy and confirmed by comparison with reported data; 24-methylenecycloartanol (1), phydroxybenzaldehyde (2), ferulic acid (3), p-coumaric acid (4), vanillic acid (5), ${\beta}$-D-(1-O-acetyl- 3-O-trans-feruloyl)fructofuranosy-${\alpha}$-D-2',4',6'.-O-triacetyglucopyranoisde (6), ${\beta}$-D-(1-O-acetyl-3,6-O-trans-diferuloyl)fructofuranosyl-${\alpha}$-D-2',4',6'.-O-triacetylglucopyranoisde (8), hydroxytyrosol acetate (9), hydroxytyrosol (10), isorhamnetin-3-O-rutinoside (11), n-butyl-${\alpha}$-D-fructofuranoside (12), and n-butyl-${\beta}$-D-fructopyranoside (13). Compounds 3 and 9-13 were isolated for the first time from this plant. The isolated compounds were tested for cytotoxicity against four human tumor cell lines in vitro using a Sulforhodamin B bioassay.
Study on the Pattern of wintering mallard using the Wild-Tracker (WT-300) in Korea
Sang-Min Jung,Park Hong Sik,Wooseog Jeong,Yong-Myong Kang,Hachung Yoon,Tehan Kang,Young-Un Shin,Si-Wan Lee,Hong-Shik Oh 한국조류학회II 2017 한국조류학회지 Vol.24 No.1
The mallard is the main wintering bird in Korea, also known as a main agent of avian virus. This study was carried out for understanding the mallard’s moving distance in winter and moving pattern from surround Mankyeong river of Korea. In 2015, 21 mallards were caught by Cannon-net, and attached the wild-tracker (WT-300, GPS-Mobile phone based telemetry, KoEco). Mallard’s moving distance between each coordinates that were transmitted by time were calculated. Monthly movement of mallards showed increasing in maximum moving distance from early November to early December, and showed distributing from the existing wintering place in December. After January, in the middle of wintering, the mallards tended to move wintering place without its big movement. Average moving distance by time in each day was 0.9 km, farthest movement was during 6:30-18:30 and after that during 6:30-8:30. Time spent in night foraging area was twice than in day foraging area. Consequently, the domestic mallards tend to distribute in December month in wintering period, after that they move short distance in the wintering area. Continuous studies on moving pattern of these species required for their protection, habitat management, and planning to the preventive measures against the high pathogenic avian influenza.
( Un Sang Yeo ),( Don Koo Lee ) 한국산림과학회 2004 한국산림과학회지 Vol.93 No.6
N/A For sustainable management of Quercus acuta stands, it is important to know how forest practice affects on natural regeneration of Q. acuta. Thinning is one of the most effective management techniques for forest improvement and successful natural regeneration. This study was carried out to examine the response of mortality and early growth of Q. acuta seedlings in natural Q. acuta stands in Wando, Jeonnam Province. Mortality of Q. acuta seedlings showed different patterns between natural unthinned Q. acuta and thinned Q. acuta stands. In the thinned stand, mortality of seedlings differed significantly among different height and diameter classes, higher mortality was shown at lower height and root collar diameter classes. However, similar mortality was observed in unthinned Q. acuta stand in all classes. Mean height and root collar diameter of total Q. acuta seedlings increased for three to four years after thinning and then slightly decreased in 2003 and 2004. But, advance regeneration continuously increased and upper 10% height class rapidly increased. In unthinned stand, higher absolute growth rate(AGR) and relative growth rate(RGR) of root collar diameter and height were shown at lower height and root collar diameter classes. On the other hand, AGR increased with tree size and RGR was relatively constant among trees of different classes except the lowest class in thinned stand.
An Assignment Problem Algorithm Using Minimum Cost Moving Method
Sang-Un Lee 한국컴퓨터정보학회 2015 韓國컴퓨터情報學會論文誌 Vol.20 No.8
Generally, the optimal solution of assignment problem has been obtained by Hungarian algorithm with O(n³) time complexity. This paper proposes more simple algorithm with O(n²) time complexity than Hungarian algorithm. The proposed algorithm simply selects minimum cost in each row, and classified into set S, H, and T. Then, the minimum cost is moved from S to T and S→H, H→T. The proposed algorithm can be obtain the same optimal solution as well-known algorithms and improve the optimal solution of partial unbalanced assignment problems.
Multiple Parallel-Pollard"s Rho Discrete Logarithm Algorithm
Sang-Un Lee 한국컴퓨터정보학회 2015 韓國컴퓨터情報學會論文誌 Vol.20 No.8
This paper proposes a discrete logarithm algorithm that remarkably reduces the execution time of Pollard’s Rho algorithm. Pollard’s Rho algorithm computes congruence or collision of α<SUP>a</SUP>β<SUP>b</SUP> ≡ α<SUP>A</SUP>β<SUP>B</SUP>(mod ρ) from the initial value a = b = o, only to derive γ from (a+bγ) = (A+Bγ), γ(B-b) = (a-A). The basic Pollard’s Rho algorithm computes χi = (χi-1)², αχi-1, βχi-1 given α<SUP>a</SUP>β<SUP>b</SUP> ≡ χ(mod ρ), and the general algorithm computes χi = (χi-1)², Mχi-1, Nχi-1 for randomly selected M=α<SUP>m</SUP>, N=β<SUP>n</SUP>. This paper proposes 4-model Pollard Rho algorithm that seeks βγ = αγ, βγ′ = α(p-1)/2+γ and βγ-1 = α(p-1)-γ) from m = n = ?√n?, (a,b) = (0.0), (1,1). algorithm that seeks βγ = α<SUP>γ</SUP>, βγ′ = α<SUP>(p-1)/2+γ</SUP> and βγ-1 = α<SUP>(p-1)-γ</SUP>) from m = n = ?√n?, (a,b) = (0.0), (1,1). The proposed algorithm has proven to improve the performance of the (0,0)-basic Pollard’s Rho algorithm by 71.70%.
Complete Time Algorithm for Stadium Construction Scheduling Problem
Sang-Un Lee 한국컴퓨터정보학회 2015 韓國컴퓨터情報學會論文誌 Vol.20 No.9
This paper suggests heuristic algorithm with linear time complexity to decide the normal and optimal point at minimum loss/maximum profit maximum shortest scheduling problem with additional loss cost and bonus profit cost. This algorithm computes only the earliest ending time for each node. Therefore, this algorithm can be get the critical path and project duration within O(n) time complexity and reduces the five steps of critical path method to one step. The proposed algorithm can be show the result more visually than linear programming and critical path method. For real experimental data, the proposed algorithm obtains the same solution as linear programming more quickly.