• 한국응용곤충학회지
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• 제33권1호
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• pp.39-50
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• 1994

한국산 날개응애류의 분류에 관한 연구중에 1신속 5신종과 5종의 한국미기록종이 밝혀졌기에 보고하는 바이다. 신속은 파도날개응애속(Kpreoribates), 5신종은 한국파도날개응애(koreoribates filia-tus), 지리산인왕응애(Hermannia neotricha), 건지산도포소매응애(Xyobates geonijensis), 성오민동정응애(defectamerus sungohi), 긴털뚜껑응애(Protorpoda flagellata)이며 신아종은 흑달걀응애(Liacarus gammatus coreanus)이고 미기록종은 북바달걍응애(Liacarus polychothomus), 갑옷뿔염주응애(Tecto-damaeus armatus), 등줄뿔염주응애(T,striatus), 머리뚜껑응애(Oripoda trilabiata), 흑팔자기게응애(Do-metorina tuberculata)등이다. 아울러 달걍응애속의 한국종, 민동정응애속, 이리뚜껑응애속(신칭의)검색표를 작성하였고 숭산달걍응애의 오기재를 바로잡았다.

• 열처리공학회지
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• 제29권6호
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• pp.284-291
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• 2016

High temperature alloy steel such as Ni-Cr-Mo-V material has excellent properties of high strength and high heating resistance. It has been used for several military weapon components such as gun barrel of a warship, turbine rotor and turbine disk for nuclear power plant. Being curious about this material required excellent wear resistance and durability in extreme environmental conditions. A dry wear test at the ambient air and Ar gas conditions in the room temperature were performed in this study. What's more a lubricant wear test at different temperature was conducted. In addition that DLC was coated on Ni-Cr-Mo-V alloy steel substrate with a thickness of $3{\mu}m$, a property of it was compare with lubricant conditions. All the coefficient of friction and wear volume, comparing with DLC coated specimens. The test parameters were selected as follows: 10 N for normal load; 80 rpm for sliding wear speed; and 300 m for the sliding wear distance.

• 한국기계가공학회지
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• 제19권3호
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• pp.29-35
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• 2020

This paper studies the main parameters of tube-to-bar dissimilar material and shape friction welding for piping materials. The weldability of joint parts was investigated with respect to tensile tests, micro-Vickers hardness, the bond of area, and optical microstructure. The specimens are tested as-welded. Optimal welding conditions are n = 2000 rpm, HP = 50 MPa, UP = 100 MPa, HT = 5 sec, and UT = 10 sec when the metal loss (Mo) is 11 mm. Moreover, the same two materials for friction welding are strongly mixed with a well-combined structure of micro-particles without any molten material, particle growth, or defects. Therefore, the expected result of dissimilar material friction welding includes a reduction of cost and material in the welding process.

• 한국재료학회지
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• 제27권10호
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• pp.552-556
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• 2017

Evaluation of the durability and stability of materials used in power plants is of great importance because parts or components for turbines, heat exchangers and compressors are often exposed to extreme environments such as high temperature and pressure. In this work, high-temperature corrosion behavior of 316 L stainless steel in a carbon dioxide environment was studied to examine the applicability of a material for a supercritical carbon dioxide Brayton cycle as the next generation power plant system. The specimens were exposed in a high-purity carbon dioxide environment at temperatures ranging from 500 to $800^{\circ}C$ during 1000 hours. The features of the corroded products were examined by optical microscope and scanning electron microscope, and the chemical compound was determined by x-ray photoelectron spectroscopy. The results show that while the 316 L stainless steel had good corrosion resistance in the range of $500-700^{\circ}C$ in the carbon dioxide environment, the corrosion resistance at $800^{\circ}C$ was very poor due to chipping the corroded products off, which resulted in a considerable loss in weight.

• 한국재료학회지
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• 제9권2호
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• pp.217-225
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• 1999

The effect on the pitting corrosion resistance of laser welding and surface treatment developed as a repair method of stream generator tubing material that was a major component of primary system at nuclear power plant was observed. Some heat-treated Alloy 600 tubing materials used at domestic nuclear power plants were laser-surface observed. Some heat-treated Alloy 600 tubing materials used at domestic nuclear power plants were laser-surface melted and the microstructural characteristics were examined. The pitting corrosion resistance was examined through Ep(pitting potential) and degree of pit generation by means of the electrochemical tests and the immersion tests respectively. The pit formation characteristics were investigated through microstructural changes and the pit initiation site and pit morphology. The test results showed that the pitting corrosion resistances was increased in the order of the followings; sensitized Alloy 600, solution annealed alloy600, and laser surface melted Alloy 600. Pits were initiated preferably at Ti-containing inclusions and their surroundings in all tested specimens and it is believed that higher pitting resistance of laser-surface treated Alloy 600 was caused by fine, homogeneous distribution of non-soluble inclusions, the disappearance of grain boundary, and the formation of dense, stable oxide film. The major element of corrosion products filled in the pit was Cr. On the other hand, Fe was enriched in the deposit formed on the pit.

• Mycobiology
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• 제46권3호
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• pp.192-204
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• 2018

The name Golovinomyces cynoglossi s. lat. is traditionally applied to a complex of morphologically similar powdery mildews on hosts of the plant family Boraginaceae. The current species-level taxonomy within this complex is ambiguous due to the lack of phylogenetic examinations. The present study applied phylogenetic methods to clarify the taxonomy of G. cynoglossi s. lat. Phylogenetic analysis of rDNA ITS sequences retrieved from Asian, European and North American specimens revealed that G. cynoglossi s. lat. collections from different hosts involved several species in five clearly separated lineages. Clade I consists primarily of Golovinomyces cynoglossi s. str. on Cynoglossum. Clade III consists of Golovinomyces sequences retrieved from the host genera Symphytum and Pulmonaria. The taxa within clade III are now assigned to G. asperifoliorum comb. nov. Clade V encompasses G. cynoglossi s. lat. on the host genera Bothriospermum, Buglossoides, Echium, Myosotis, and Trigonotis. The taxa within clade V are now assigned to G. asperifolii comb. nov. The species concerned in this study were lecto- and epitypified to stabilize their nomenclature.

• Journal of Welding and Joining
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• 제31권4호
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• pp.73-79
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• 2013

Burr grinding, Tungsten Inert Gas (TIG) dressing, ultrasonic impact treatment, and peening are used to improve fatigue life in steel structures. These methods improve the fatigue life of weld joints by hardening the weld toe, by improving the bead shape, and by creating the compressive residual stress. In this study, a new post-weld treatment method improving the weld bead shape and metal structure at the welding zone using Friction Stir Processing (FSP), a welding process, is proposed to enhance fatigue life. For that, a pin-shaped tool and processing condition employing Friction Stir Processing (FSP) is established through experiments. Experimental results revealed that fatigue life is improved by around 50% compared to as-welded fatigue specimens by reducing the stress concentration at the weld toe and by generating a metal structure finer than that of flux-cored arc welding (FCAW).

• Journal of the Korean Wood Science and Technology
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• 제11권1호
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• pp.5-11
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• 1983

This paper aims at gaining the informations atout the fibril angle at secondary walls of tracheids. The test specimens were taken from disks on stem wood of "Pinus koraiensis Sieb. et zucc". The method of measuring the fibirl angle was selected so-called "iodine method" that crystalline aggregates of iodine may be induced to form within the elongated interstices of the cellulose matrix of the secondary wall and that these elongated crystals are oriented parallel to the long axies of the fibrills of cellulose. The following conclusions may be drawn from the results of this investigation. 1) Gross average fibril angle was about $17.6^{\circ}$ on stem wood. 2) Its values seem to be greater for earlywood (avg.$19.8^{\circ}$) than for latewood tracheids (avg.$15.3^{\circ}$) in normal wood. 3) According to the increase of annual ring from pith to barks the orientation of fibril angle seems to be decrease gradually in normal wood. 4) In the case of height variation in trees the sample trees have a tendency to increase the orientation fibril angle to the increase of tree height in stem.

• Journal of Species Research
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• 제9권1호
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• pp.46-55
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• 2020

Chrysosplenium grayanum Maxim. (Series Nepalensia), which had been known to be restricted to Japan, was newly discovered from Mt. Cheongtae in Yeonggwang-gun, Jeollanam-do, located in the southern part of the Korean Peninsula. Species identification was confirmed using morphological characteristics and DNA sequence data, while comparing with materials obtained from Japan and herbarium specimens. Chrysosplenium grayanum is clearly distinguished from the remaining taxa of the genus Chrysosplenium by having glabrous plant body, opposite leaves, cylindrical papillae with roundish head at the tip on the smooth seed surface, and four stamens. Molecular sequence data of the nuclear ribosomal ITS regions, chloroplast rbcL and matK genes strongly supported that this previously unknown Chrysosplenium species from Korea is C. grayanum. Taking the molecular and the morphological evidence into consideration, it is clear that newly discovered Chrysosplenium population in Korea is conspecific with the widely distributed C. grayanum in Japan. In this paper, we provide a description, illustration, and photo images of Chrysosplenium grayanum from Korea and also a key to the Chrysosplenium species in Korea.

• 한국안전학회지
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• 제17권4호
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• pp.5-10
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• 2002

For fitness-for-service evaluation of high temperature plant components with defects, crack growth life must be assessed properly as indicated in the recent draft of API 579 code. Type 308 stainless steel has been widely used as a field weld material in the petrochemical industry. In this study, creep crack data of type 308 stainless steel are collected and re-analyzed using $C_t$ as a characterizing fracture parameter. A unique da/dt versus $C_t$ relationship was obtained despite of difference of creep deformation constant of the reviewed materials and specimen geometry of the tested specimens. The obtained results can be employed for crack growth life assessment and fitness-for-service evaluation for the cracks in high temperature components. It is also argued that since the effect of creep properties and other material variability on the creep crack growth behavior would be minor the obtained model may be applied for most of the 308 stainless steels.