• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.1-7
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• 2010

The paper proposes a multi-body dynamic simulation to numerically evaluate the generated axial force(G.A.F) and plunging resistant force(P.R.F) practically related to the shudder and idling vibration of an automobile. A numerical analysis of two plunging types of CV joints, tripod joint(TJ) and very low axial tripod joint(VTJ), is conducted using the commercial program DAFUL. User-defined subroutines of a friction model illustrating the contacted parts of the outboard and inboard joint are subsequently developed to overcome the numerical instability and improve the solution performance. The Coulomb friction effect is applied to describe the contact models of the lubricated parts in the rolling and sliding mechanisms. The numerical results, in accordance with the joint articulation angle variation, are validated with experimentation. The offset between spider and tulip housing is demonstrated to be the critical role in producing the 3rd order component of the axial force that potentially causes the noise and vibration in vehicle. The VTJ shows an excellent behavior for the shudder when compared with TJ. In addition, a flexible nonlinear contact analysis coupled with rigid multi-body dynamics is also performed to show the dynamic strength characteristics of the rollers, housing, and spider.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.4
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• pp.343-348
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• 1984

Variation of soil properties within mapping unit of lava plain soils was statistically summarized. Properties such as particle size distribution, moisture retention, color, pH, and CEC are relatively unaffected by soil management while Na, K, base saturation, and available $P_2O_5$ most affected by management. These soils were correctly classified with regard to order at 66.5, to greatgroup at 56.0, and to series at 43.8%. CV values greater than 90% could be symptomatic of skew distribution. Distributions of sand content and some chemical properties were log-normal.

• Korean Journal of Materials Research
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• v.21 no.3
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• pp.180-185
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• 2011

This study is aimed to increase the activity of cathodic catalysts for PEMFCs(Polymer Electrolyte Membrane Fuel Cells). we investigated the temperature effect of 20wt% Pt/C catalysts at five different temperatures. The catalysts were synthesized by using chemical reduction method. Before adding the formaldehyde as reducing agent, process was undergone for 2 hours at the room temperature (RT), $40^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$ and $100^{\circ}C$, respectively. The performances of synthesize catalysts are compared. The electrochemical oxygen reduction reaction (ORR) was studied on 20wt% Pt/C catalysts by using a glassy carbon electrode through cyclic voltammetric curves (CV) in a 1M H2SO4 solution. The ORR specific activities of 20wt% Pt/C catalysts increased to give a relative ORR catalytic activity ordering of $80^{\circ}C$ > $100^{\circ}C$ > $60^{\circ}C$ > $40^{\circ}C$ > RT. Electrochemical active surface area (EAS) was calculated with cyclic voltammetry analysis. Prepared Pt/C (at $80^{\circ}C$, $100^{\circ}C$) catalysts has higher ESA than other catalysts. Physical characterization was made by using X-ray diffraction (XRD) and transmission electron microscope (TEM). The TEM images of the carbon supported platinum electrocatalysts ($80^{\circ}C$, $100^{\circ}C$) showed homogenous particle distribution with particle size of about 2~3.5 nm. We found that a higher reaction temperature resulted in more uniform particle distribution than lower reaction temperature and then the XRD results showed that the crystalline structure of the synthesized catalysts are seen FCC structure.

• The Korean Journal of Mycology
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• v.32 no.2
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• pp.130-133
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• 2004

Leaf blight and fruit rot of sweet persimmon (cv. Fuyu) caused by Pestalotia diospyri were observed during the growing season and postharvest such as storage and transport, respectively. Typical symptoms on leaves developed with small brown spots and were later reddish brown colors. In the storage fruit, the white mycelial mats formed between fruit and calyx. The pathogenic fungus was isolated from infected fruits and cultured on potato dextrose agar (PDA). Colony color of the fungus was white at first on PDA. Conidia were ovoid or fusiform, 5 cells, middle 3 cells were olive, upper and lower 2 cells were colorless, and their size were $16{\sim}22\;{\times}\;6{\sim}8\;{\mu}m$. They had were $2{\sim}3$ appendage at basal cell and size $9{\sim}18\;{\mu}m$. Based on the cultural and mycological characteristics and pathogenicity test on host plants and fruits, the fungus was identified as Pestalotia diospyri Syd.&P. Syd. This is the first report on the leaf blight and fruit rot of sweet persimmon caused by Pestalotia diospyri in Korea.

• The Plant Pathology Journal
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• v.27 no.3
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• pp.266-271
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• 2011

Physicochemical characteristics and heavy metal content of soils located along the drainage way of an abandoned mine at Busan, Korea ($35^{\circ}31'N$, $129^{\circ}22'E$) (contaminated soil; CS) and uncontaminated soils (50-70 m apart from the drainage way) (NS) were examined. Growth of tomato plants (Solanum lycopersicom cv. Rutgers) in CS and NS, development of the root-knot nematode (Meloidogyne incognita) as root-knot gall formation on tomato plants, and non-parasitic nematode populations in soil were also examined. Growth of tomato plants, root-knot gall formation, and non-parasitic nematode populations were significantly reduced in CS with higher As content, lower pH, higher electrical conductivity (EC), and lower available phosphate (av. $P_2O_5$) than in NS. None of the other physicochemical characters examined differed significantly between CS and NS (low and no significance) and were above or below the critical levels detrimental to plant growth and nematode development, suggesting that As may be the primary hazardous heavy metal in CS. The toxicity of As might be enhanced at low pH in CS because exchangeable forms of some heavy metals increase with the decrease of soil pH. The heavy metals, especially As, may have contributed to increasing EC and decreasing av. $P_2O_5$. Therefore, the effects of mine drainage contamination from the abandoned mine were derived primarily from contamination by heavy metals such as As. These may have been enhanced in toxicity (solubility) by the lowered pH, increased soil salinity (EC) and decreased av. $P_2O_5$. Our results suggest synergistic adverse effects on the plant and the nematode by decreasing osmotic potential and nutrient availability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.338-338
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• 2010

지난 20여년 동안 반도체 레이저 다이오드는 주로 CD (DVD) 픽업용 (파장: 640 nm 이하) 및 통신용 (파장 1550 nm) 광원 분야에서 집중적으로 개발되어 왔다. 그러나 기술의 개발과 더불어 파장조절이 비교적 자유로워지고 광출력이 증대 되면서 기존의 레이저 고유의 영역까지 그 응용분야기 확대되고 있고, 이에 따라 고출력 반도체 레이저 다이오드의 시장 규모도 꾸준히 증가되고 있는 상황이다. 고출력 반도체 레이저 다이오드는 발진 파장 및 광출력에 따라 다양한 분야에 응용되고 있으며, 특히 발진파장이 808 nm 인 고출력 레이저 다이오드의 경우 재료가공, 펌핑용 광원 (DPSSL, 광섬유 레이저), 의료, 피부미용 (점 제거), 레이저 다이오드 디스플레이 등 가장 다양한 응용분야를 가진 광원 중의 하나라고 할 수 있다. MBE(Molecular Beam Epitaxy)로 성장된 InAlAs 에피층 (epi-layer)을 사용하여 고출력을 갚는 레이저 다이오드를 제작함에 있어서, 에피층은 결함 (defect)이 없는 우수한 단결정이 요구되지만, 실제 결정 성장 과정에서는 성장온도와 Al 조성비 등의 성장 조건의 변화에 따라 전기적 광학적 특성 및 신뢰성에 큰 영향을 받는 것으로 보고되고 있다. 이에 본 연구에서는 DLTS (Deep Level Transient Spectroscopy) 방법을 이용하여 InAlAs 양자점 에피층의 깊은 준위 거동을 조사하였다. DLTS 측정 결과, 0.3eV 부근의 point defect과 0.57 ~ 0.70 eV 영역의 trap이 조사되었으며, 이는 갈륨 (Ga) vacancy와 산소 원자의 복합체에 기인한 결함으로 분석된다.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3576-3582
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• 2014

Zeolite-templated carbons (ZTCs), which have high specific surface area, were prepared by a conventional templating method using microporous zeolite-Y for catalyst supports in direct methanol fuel cells. The ZTCs were synthesized at different temperatures to investigate the characteristics of the surface produced and their electrochemical properties. Thereafter, Pt-Ru was deposited at different carbonization temperatures by a chemical reduction method. The crystalline and structural features were investigated using X-ray diffraction and scanning electron microscopy. The textural properties of the ZTCs were investigated by analyzing $N_2$/77 K adsorption isotherms using the Brunauer-Emmett-Teller equation, while the micro- and meso-pore size distributions were analyzed using the Barrett-Joyner-Halenda and Harvarth-Kawazoe methods, respectively. The surface morphology was characterized using transmission electron microscopy and inductively coupled plasma-mass spectrometry. The electrochemical properties of the Pt-Ru/ZTCs catalysts were also analyzed by cyclic voltammetry measurements. From the results, the ZTCs carbonized at $900^{\circ}C$ show the highest specific surface areas. In addition, ZTC900-PR led to uniform dispersion of Pt-Ru on the ZTCs, which enhanced the electro-catalytic activity of the Pt-Ru catalysts. The particle size of ZTC900-PR catalyst is about 3.4 nm, also peak current density from the CV plot is $12.5mA/cm^2$. Therefore, electro-catalytic activity of the ZTC900-PR catalyst is higher than those of ZTC1000-PR catalyst.

• Research in Plant Disease
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• v.7 no.1
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• pp.8-10
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• 2001

A stem and root rot disease of kalanchoe (Kalanchoe sp.) which is a succulent plant that provides consumers with a durable flowering pot was found in Koyang, Kyounggi province, Korea in May 1998. We found that stems and roots of potted kalanchoe had dark brown spots at the soil level. The causal organism was identified as Pjytophtora nicotianae on the basis of mycological characteristics. The fungus produced markedly papillate, ovoid to spherical sporangia, and abundant chlamydospores. Sporangia were 20∼48$\times$24∼64㎛(avg. 35.0$\times$47.3㎛) in size, and optimum temperature for the mycelial growth of the isolate was 30$\^{C}$. The fungus showed relatively different pathogenicity to 14 kalanchoe cultivars including K. blossfelana cv. Florus. cultivars florsu, calypso, Maya, and Redsing were susceptible to thedisease in root dip inoculation. This is the first report demonstrating the stem rot on kalanchoe caused by P. nicotianae in Korea.

• Research in Plant Disease
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• v.10 no.2
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• pp.117-120
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• 2004

In April of 2003, the gray mold disease occurred severely on statice (Limonium shinuatum Mill. cv. Sophia) grown in the commerical farms in Seosang-myon, Hamyang-gun, Gyeongnam Province, Korea, 2003. The infected plants were started with water-soaking lesions in the stems, the leaves and the flowers became withered and discolored to gray or dark from the tip then gradually expanded to die. The conidia and mycelia of the pathogen appeared on flowers, leaves, calyx and flower stalk. The conidia were gray, I-celled, mostly ellipsoid or ovoid in shape and were 8∼20 x 6∼14 ${\mu}{\textrm}{m}$ in size. Conidiophores were 14∼34 ${\mu}{\textrm}{m}$ in size. The sclerotia were formed abundantly on potato-dextrose agar. The optimum temperature for sclerotial formation was 2$0^{\circ}C$. Pathogenicity of the causal organism was proved according to Koch's postulate. The causal organism was identified as Botrytis cinerea Persoon: Fries based on mycological characteristics. This is the first report on gray mold of statice (Limonium shinuatum) caused by Botrytis cinerea in Korea.

• Proceedings of the KSPS conference
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• 1996.10a
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• pp.252-257
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• 1996

La structure syllabique est un facteur important dan la prononciation d'une langue. Dans cette these, on a essaye de montrer que les caracteristiques de la syllabe varie d'une langue a une autre, et que les regles qui regissent la syllabe dan la langue maternelle a le dessue et done fait appliquer ses regles a la langue etrangere. Premierement, l'accentuation du coreen depend de la structure syllabique (qu'elle soit consonne-voyelle(CV) ou consonne-voyelle-consonne(CVC) et de la longueur de la voyelle. Ce qui fait que bien que le francais soit oxyton, et que la longueur et la qualite de la voyelle dependent de la structure syllabique, le francais, le francais parle par les coreens suit les regles du coreen. Autre caracteristique est que le coreen n'admet pas de suite de consonnes avant et apres la voyelle centrale comme dans "premier"[$pr{\partial}mje$] "autre"[o:tR]. D'ou l'insertion de voyelle superflue comme [${\varpi},{\;}{\wedge},{\;}{\partial}$]. Troisiemement, il existe une difference dans la coupe de la chaine parlee: en coreen la coupe ecrite(le blanc) egale a peu pres a la coupe orale(la pause) alors qu'en francais, c'est en groupe de mots que se fait la coupe. A l'interieur du groupe, les mots sont lies entre eux, soity par liaison, soit par enchainement. On peut remarquer donc une nette influence du coreen, ou la regle est de prononcer correctement par unites ecrites (equivalent des mots en francais) : la chaine parlee devient saccadee, avec un accent sur tous les mots, et des coups de glotte entre les mots, et l'une des voyelles [${\varpi},{\;}{\wedge},{\;}{\partial}$] inseree entre un mot se terminant par une consonne suivi d'un mot qui commence par une consonne.