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      • O/W · W/O Emulsion의 Tribology 특성 연구

        이봉구,임웅빈,오성모 원광대학교 생산 및 자동화기술연구소 1995 생산.자동화기술연구소논문집 : 원광대 Vol.- No.2

        We have been so much interested in the lubrication of emulsion property recently. In particular, O/W and W/O type emulsion have a good property to be used in the Lubricative situation of several services. Therefore, in this section we have studied about the lubricational characteristics in Neat Oil, O/W and W/O type emulsion using the Falex, wear test machine. The result is as follows. 1. In the case of O/W and W/O type emulsion, the beginning friction coefficient than Neat Oil, but it becomes more excellent as the time passes. especially, the W/O type becomes the more excellent. 2. As the load increase, a change in temperature shows to us be nearly similar and all of them, the O/W type is the most excellent in the temperature characteristic. 3. In the beginning, the anti-wear characteristic of emulsion lowers, but after the some load has stability, O/W and W/O type is excellent in order of anti-wear characteristic. 4. In the regular hours, a change in the emulsion becomes settled, so the character of temperature is superior. specially, O/W type is predominant. Therefore, the emulsion in case of the O/W and W/O type are more excellent than Neat oil in the thermal stability and can improve the characteristics of tribology.

      • Ni - W 합금전착층중의 W 함량과 열처리에 따른 결정구조 및 기계적 성질 변화에 관한 연구

        황운석,유황룡,이수갑,장시성 한국부식학회 2001 Corrosion Science and Technology Vol.30 No.3

        Effects of W content and heat-treatment on crystal structure and mechanical property of Ni-W alloy deposit were investigated. Ni-W alloy deposits containing 17wt.% to 41wt.% W were obtained by electrodeposition method from a citric acid-ammonia deposition solution. From results of XRD and SEM analyses, the Ni-W alloy deposit preferentially grew (111) orientation and Ni-20wt.% W deposit as a solid solution had higher lattice parameter than pure Ni. Its crystal structure was transformed from Ni-W solid solution to the mixture of fine grain and amorphous structure with increasing W content. Therefore the flatness of Ni-W alloy deposit was increased. The microhardness of Ni-W alloy deposit was slightly increased from 550VHN to 625VHN with increasing W content due to solid solution hardening and grain refinement effects. The hardness was increased with an elevation of heat-treatment temperature and showed the highest value of 1360VHN at 600℃. The hardness of Ni-W alloy deposit which was heattreated in low vacuum degree (60 Torr) was higher than that in high vacuum degree (1.2×10^(-5) Torr). It was considered that WO₃ was precipitated in the low vacuum degree.

      • Mechanical properties of (W,Ti)C and (W,Ti)C-NiAl<sub>3</sub> cermet consolidated by the high-frequency induction-heating method

        Kim,,W.,Suh,,C.Y.,Roh,,K.M.,Cho,,S.W.,Na,,K.I.,Shon,,I.J. Elsevier Sequoia 2013 Journal of alloys and compounds Vol.568 No.-

        In the case of cemented (W,Ti)C, Co is added as a binder for the formation of composite structures. However, the high cost of Co and the low corrosion resistance of the (W,Ti)C-Co cermet have generated interest in recent years for alternative binder phases. In this study, NiAl<SUB>3</SUB> was used as a binder and consolidated by the high-frequency induction heated sintering (HFIHS) method. The densification of both monolithic (W,Ti)C and (W,Ti)C-NiAl<SUB>3</SUB> cermet was accomplished within 3min. Highly dense (W,Ti)C and (W,Ti)C-NiAl<SUB>3</SUB> with a relative density of upto 99% were obtained within 3min by HFIHS under a pressure of 80MPa. The method was found to enable not only the rapid densification but also the prohibition of grain growth preserving the nano-scale microstructure. The average grain sizes of the sintered (W,Ti)C and (W,Ti)C-NiAl<SUB>3</SUB> were lower than 100nm. The addition of NiAl<SUB>3</SUB> to (W,Ti)C enhanced the toughness at the expense of the slight decrease in hardness. The hardness of (W,Ti)C and (W,Ti)C-NiAl<SUB>3</SUB> was significantly higher than that of (W,Ti)C-Co or (W,Ti)C-Ni. The fracture toughness and hardness values of (W,Ti)C, (W,Ti)C-5vol.%NiAl<SUB>3</SUB>, and (W,Ti)C-10vol.%NiAl<SUB>3</SUB> consolidated by HFIHS with a pressure of 80MPa and a induced current were 7.6+/-0.4MPam<SUP>½</SUP> and 2850+/-35kg/mm<SUP>2</SUP>, 8.5+/-0.3MPam<SUP>½</SUP> and 2610+/-37kg/mm<SUP>2</SUP>, 9.7+/-0.5MPam<SUP>½</SUP> and 2520+/-26kg/mm<SUP>2</SUP>, respectively.

      • 터키種 잎담배 生産에 關한 硏究

        盧載榮,鄭元采,安長憲,卞珠燮,姜信寓 충북대학교 엽연초연구소 1974 煙草硏究 Vol.2 No.-

        I.Influence of deficient or excessive supply of soil moisture. The variety used in this study were Turkish varieties (Smyrna, Samsun, Zichna and Xanthi). Soil moisture content were 30%, 45% and 60% to maximum water-holding capacity for whole growth period. This experiment was carried out to study on the influence of soil moisture to growth and physiology of Turkish varieties. The results are summarized as follow ; a. Dry weight of Samsun and Zichna were-increased at 45% soil moisture content, but Smyrna and Xanthi at 60%. In every soil moisture treatmennt, there were significant difference between D plot and M, W plot but there were no significant difference between M plot and W plot. b. Percentage of dry matter of Smyrna was higher then those of the other varieties in the D plot and W plot. c. Leaf area was increased ill the Samsun of which process was slightly late. In every soil moisture treatment, M plot and W plot were higher than D plot. d. Dry weight per unit leaf area of Smyrna and Zichna were higher than that of Xanthi and Samsun. e. Percentage of dried up leaves was the W plot, and lower at the D and M plot. Smyrna was lower at M plot, Zichna at D and M plot, Xanthi at D plot, but Samsun was no difference among plots. f. In the number of harvested leaves, Smyrna was increased in order W>M>D. In the number of harvested leaves, Smyrna showed difference according to the soil moisture in order W>M>D plot, but Samsun and Zichna showed no difference among each treatments, Xanthi was higher in M plot than D and W plot. From those results, Smyrna showed the highest dry weight on account of the weight of leaf area and percentage of dry weight increased, it was decreased in order Zichna>Samsun Xanthi in the each soil moisture contents. Number of harvested leaves, dried up leaves, leaf area and number of harvested leaves but decreased, percentage of dry matter W treatment increased the number of total leaves, number of dried up leaves, leaf area, percentage of dried up leaves and percentage of dry matter. Yields were the lowest at D treated, there were no difference between M and W treatment. II.Influence of deficient or excessive supply of soil moisture at different growing stages. This experiment was carried out to study on the influence to the growth and physiology according to the soil moisture content during each growth stage on Turkish varieties culture. The varieties used in this study were Samsun, Zichna and Xanthi. The results are summarized as follow; a. Dry leaf weight was decreased in order Zichna>Samsun>Xanthi, there were remakable difference among every variety. In each soil moisture content, weight of dry matter was increased by M and W treated at late stage after MW and MM treated at early and middle stage of growth DWM and MDM plot. Dry leaf weight was decreased at D plot more than M and W plot late stage after early stage was treated by MW and MM. Dry leaf weight was the highest at WWM treate, dthere were high significant difference between varieties and soil moisture contents. b. Percentage of dry matter was decreased in order Zichna=Xanthi>Samsun. In soil moisture treated, it was increased in D treated at the latter stage after MM, MW and WM treated at early and middle stage, but it was decreased by DDM, DWD, MDM, WWD, WMM, and WWM treated. There were high significant interaction between varieties and soil moisture contents. c. Leaf area showed in order Samsun=Zichna>Xanthi. In soil moisture treated, leaf area was increased by WM, MM and MW treated at the middle and latter stage after D treated at early stage, but it was decreased at WWD, WMD, WWM, MWD and MMD treated. d. Dry weight per unit leaf area were no difference among varieties, in soil moisture treated, it was increased by the MMW, MWD, MMD, WMD and DMW treated, weight of per unit leaf area showed significant difference interaction between varieties and soil moisture contents. d. Percentage of dried up leaves showed as follow, Samsun>Xanthi, Samsun=Zichna, Zihna=Xanthi. In soil moisture treated, it was increased by M and W treated at early stage than D treated. f. Number of harvested leaves was decreased in order Xanthi>Samsun>Zichna, there were no difference among soil moisture contents, but appeard high significant difference at the interaction between varieties and soil moisture contents. As the results of this experiment, especially, this experiment will be continue on the influence of soil moisture condition in order to development of home production system.

      • SCISCIESCOPUS

        OH (1720 MHz) MASERS: A MULTIWAVELENGTH STUDY OF THE INTERACTION BETWEEN THE W51C SUPERNOVA REMNANT AND THE W51B STAR FORMING REGION

        Brogan,,C.,L.,Goss,,W.,M.,Hunter,,T.,R.,Richards,,A.,M.,S.,Chandler,,C.,J.,Lazendic,,J.,S.,Koo,,B.-C.,Hoffman,,I.,M.,Claussen,,M.,J. IOP Publishing 2013 The Astrophysical journal Vol.771 No.2

        <P>We present a comprehensive view of the W51B H II region complex and the W51C supernova remnant (SNR) using new radio observations from the VLA, VLBA, MERLIN, JCMT, and CSO along with archival data from Spitzer, ROSAT, ASCA, and Chandra. Our VLA data include the first lambda = 400 cm (74 MHz) continuum image of W51 at high resolution (88 ''). The 400 cm image shows non-thermal emission surrounding the G49.2-0.3 H II region, and a compact source of non-thermal emission (W51B_NT) coincident with the previously-identified OH (1720 MHz) maser spots, non-thermal 21 and 90 cm emission, and a hard X-ray source. W51B_NT falls within the region of high likelihood for the position of TeV gamma-ray emission. Using the VLBA, three OH (1720 MHz) maser spots are detected in the vicinity of W51B_NT with sizes of 60-300 AU and Zeeman effect magnetic field strengths of 1.5-2.2 mG. The multiwavelength data demonstrate that the northern end of the W51B HII region complex has been partly enveloped by the advancing W51C SNR and this interaction explains the presence of W51B_NT and the OH masers. This interaction also appears in the thermal molecular gas which partially encircles W51B_NT and exhibits narrow pre-shock (Delta v similar to 5 km s(-1)) and broad post-shock (Delta v similar to 20 km s(-1)) velocity components. RADEX radiative transfer modeling of these two components yield physical conditions consistent with the passage of a non-dissociative C-type shock. Confirmation of the W51B/W51C interaction provides additional evidence in favor of this region being one of the best candidates for hadronic particle acceleration known thus far.</P>

      • Preparation of Ni-W-Si<sub>3</sub>N<sub>4</sub> composite coatings and evaluation of their scratch resistance properties

        Gyawali,,G.,Joshi,,B.,Tripathi,,K.,Lee,,S.W. Ceramurgica ; Elsevier Science Ltd 2016 CERAMICS INTERNATIONAL Vol.42 No.2

        In this study, Ni-W-Si<SUB>3</SUB>N<SUB>4</SUB> nanocomposite coatings have been prepared by codeposition of Si<SUB>3</SUB>N<SUB>4</SUB> nanoparticles into Ni-W alloy coatings having different W contents. The surface morphology and elemental contents in the alloy composite coatings have been analyzed by scanning electron microscopy coupled with EDS. Structure and phase composition were evaluated by using X-ray diffraction (XRD). Progressive type of scratch test was carried out by the scratch tester using a diamond indenter. Results indicated that Vickers microhardness of the Ni-W-Si<SUB>3</SUB>N<SUB>4</SUB> composite coatings is found to be higher in comparison to the corresponding Ni-W coatings. In addition, a small increase in Vickers microhardness was observed in Ni-W coatings with higher content of tungsten. Apart from that, a significant influence had been found on scratch resistance properties with the codeposition of Si<SUB>3</SUB>N<SUB>4</SUB> and variation of W contents in Ni-W-Si<SUB>3</SUB>N<SUB>4</SUB> nanocomposite coatings. Ni-W-Si<SUB>3</SUB>N<SUB>4</SUB> nanocomposite with 12.7at% W and 2.1wt% Si<SUB>3</SUB>N<SUB>4</SUB> has shown improved scratch resistance among others.

      • KCI등재

        전착조건에 따른 Ni - W 합금전착에 관한 연구

        황운석,유황룡,이수갑,문재열,장시성 한국부식학회 2001 Corrosion Science and Technology Vol.30 No.3

        Effects of various electrodeposition conditions and ion concentration contained in solution on Ni-W alloy deposit were investigated. Electrodeposition was performed with various conditions : current density, temperature, pH, and W, Na^+ and SO₄^(2-) concentrations in citrate-containing solution. In the both solutions containing W concentrations of 0.144M and 0.212M, as the current density was increased, current efficiency was decreased but W content in the Ni-W alloy deposit was increased and reached the highest value of 41wt.% in the W concentration of 0.212M. When the pH was increased, the current efficiency was increased because the H₂ evolution reaction was decreased on the cathode surface. As the temperature was increased, the current efficiency was increased and the W content was increased up to 41wt.%. From the above results, the highest W content in the deposit was 41wt.% and the optimal conditions for the Ni-41wt.%W alloy deposit were current density of l0A/dm², temperature of 70℃, pH 6 and W concentration of 0.212M. In addition, as the Na+ ion concentration was increased, the current efficiency was decreased but nearly constant with an addition of NH₄OH. Cathodic voltage was decreased with adding NH₄OH. It was considered that NH90H played a role as a ligand for metallic complexes in the solution. SO₄^(2-) ion may have not affected the electrodeposition behavior.

      • KCI우수등재

        중부 평야지에서 사일리지용 옥수수 품종 선발에 관한 연구 : 파종시기가 사일리지용 옥수수의 생육특성 및 수량에 미치는 영향 Effect of planting time on the growth and yield of silage corn

        김준식,김원호,김원영,김영진,한학석,김맹중 한국축산학회 1998 한국축산학회지 Vol.40 No.1

        This experiment was conducted at theForage Research Farm of the Beef and Dairy Cattle Division, National Livestock Research Institute, Songhwan in 1992 and 1995 to investigate the effects of planting time (April 15, May 11, June 5) on the growth and yield of silage com(Zea mat's L.). In the plant height, P3144W and DK729 were taller than the others, as 301.6, and 296.3cm, respectively, and P3282 was the shortest as 247.7㎝ at the first planting time. P3144W and DK729 were taller than the others, as 303.6㎝, 281.7㎝, respectively, and P3282 was the shortest as 249.6㎝ at the second planting time. P3144W was the tallest as 276.9㎝. DK689 was the shortest as 246.1㎝ at the third planting time. The ear heights of P3144W and P3282 were 137.3 and 132.7㎝, respectively, and Suweon 19 was the shortest as 116.4㎝ at the first planting time. Those of P3144W and P3282 were as 135.9, 134.4㎝, respectively, and Suwoen 19 was the shortest as 112.1㎝ at the second planting time. P3144W was the tallest as 111.0㎝ and Suweon 19 was the shortest as 94.2㎝ at the third planting time. In the dry matter yield per ha, P3352, DK729 and P3144W were higher than the others as 18,957, 18,840, 18,743㎏, respectively, and P3282 was the lowest as 13,863㎏ at the first planting time. 64743 and P3352 were 18,183 and 17,874㎏, respectively, and Suwoen 19 was the lowest as 15,007㎏ at the second planting time. P3144W was the highest as 19,112㎏ and Suwnen 19 was the lowest as 14,793㎏ at the third planting time. The TDN yield per ha, of P3352, P3144W and DK729 were 13,552, 13,281 and 13,252㎏, respectively, and P3282 was the lowest as 9,793㎏ at the first planting time. 64743 and P3352 were higher than the others as 13,149 and 13,009kg, respectively, and Suwoen 19 was the lowest as 10,872㎏ at the second planting time. P3144W was the highest as 13,521㎏ and Suwven 19 was the lowest as 10,392㎏ at the third planting time.

      • SCIESCOPUSKCI등재

        Study of the genus Woldstedtius Carlson (Hymenoptera; Ichneumonidae; Diplazontinae) with description of three new species in South Korea

        Balueva,,E.N.,Lee,,J.W. 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.2

        <P>In this paper, a taxonomic review of the genus Woldstedtius Carlson in Korea with a key to the twelve Eastern Palearctic species is provided. Two species-W. yokohamensis and W. karafutensis, which were described by Uchida from Japan-are re-described based on holotype re-examination and the study of Korean material. The male of W. karafutensis Uchida is reported for the first time. Three species, W corvinus sp. nov., W. nigrosignatus sp. nov., and W. pallidus sp. nov., are described as new. Five species, W. biguttatus Gravenhorst, W. citropectoralis Schmiedeknecht, W. holarcticus Diller, W. karafutensis Uchida, and W. yokohamensis Uchida, are reported from Korea for the first time. (C) 2015 Published by Elsevier B.V. on behalf of Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society.</P>

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