• Title, Summary, Keyword: Wet test

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Determination of Opening Size of Geotextiles (토목섬유의 유효구멍크기 측정방법 및 측정결과 평가)

  • Cho, Sam-Deok;Kim, Ju-Hyong;Lee, Kwang-Wu
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.111-120
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    • 2006
  • Opening size of 3 types of geotextile were tested using dry and wet sieving methods to evaluate characteristics of test methods and to compare the test results. Judging from test results, dry sieving method is a poor test, having many problems causing many errors but a simple-quick test. Wet sieving method is a very specific test avoiding many of the problems of dry sieving such as electrostatic charges, trapping in the geotextiles and so on. However, one of wet sieving tests, KSK ISO12956, takes long time to complete a test and is too strict to handle loss of granular material. Generally, opening size of a geotextile by wet sieving test is smaller than that of dry sieving test. Especially, opening size by KSF 2126 which is one of wet sieving test but disused at present anymore is similar or smaller than that by KSK ISO12956 method.

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Opening Size Determination of Geotextiles Using Dry and Wet Methods (건식/습식 방법을 이용한 토목섬유의 유효구멍크기 측정방법 평가)

  • Kim, Ju-Hyong;Cho, Sam-Deok
    • Journal of the Korean Geotechnical Society
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    • v.23 no.2
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    • pp.19-27
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    • 2007
  • Dry and wet test methods established by Korean industrial standards to estimate opening size of 3 types of geotextile which are widely used for filter of plastic drain board in Korea are performed to evaluate characteristics of the test methods and to compare the test results. Judging from test results, dry method is a relatively poor test, having lots of problems causing many errors but a simple-quick test. Wet method is a very specific test avoiding many of the problems of dry method such as electrostatic charges, trapping in the geotextiles and so on. However, one of wet test methods, KS K ISO 12956, takes long time to complete a test and is too strict to handle loss of granular material. Generally, opening size of a geotextile by wet test method is smaller than that of dry test method. Especially, opening size by KS F 2126 which is called hydrodynamic method but at present is not used anymore is similar to or smaller than that by KS K ISO 12956 method.

Application of WCT (Wet Compaction Test) to Mixed Fiber Furnishes (Wet compaction test를 이용한 혼합지료의 적용)

  • Seo Yung B.;Lee Chun Han
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.37 no.4
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    • pp.8-17
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    • 2005
  • WCT (Wet compaction test) is a new fiber evaluation method developed recently by Seo and its test results can be used as a predictor for pulp quality and its paper property Bleached chemical pulps (SwBKP, HwBKP), recycled pulp (OCC), and mechanical pulp (BCTMP) were used for the furnishes to be tested by WCT We compared the WCT results to conventional fiber evaluation tests such as WRV (Water Retention Value), free ness, and fiber length in this study, and found that WCT always gave better regression coefficients in relation to pulp quality (drainage), and paper properties (density, tensile, tear, and burst strength). WCT may be used on-line in papermachine.

Influence of Wet Chemistry Damage on the Electrical and Structural Properties in the Wet Chemistry-Assisted Nanopatterned Ohmic Electrode (Wet chemistry damage가 Nanopatterned p-ohmic electrode의 전기적/구조적 특성에 미치는 영향)

  • Lee, Young-Min;Nam, Hyo-Duk;Jang, Ja-Soon;Kim, Sang-Mook;Baek, Jong-Hyub
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.150-150
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    • 2008
  • 본 연구에서는 Wet chemistry damage가 Nanopatterned p-ohmic electrode에 미치는 영향을 연구하였다. Nanopattern은 Metal clustering을 이용하여, P-GaN와 Ohmic형성에 유리한 Pd을 50$\AA$ 적층한 후 Rapid Thermal Annealing방법으로 $850^{\circ}C$, $N_2$분위기에서 3min열처리를 하여 Pd Clustering mask 를 제작하였다. Wet etching은 $85^{\circ}C$, $H_3PO_4$조건에서 시간에 따라 Sample을 Dipping하는 방법으로 시행하였다 Ohmic test를 위해서 Circular - Transmission line Model 방법을 이용하였으며, Atomic Force Microscopy과 Parameter Analyzer로 Nanopatterned GaN surface위에 형성된 Ni/ Au Contact에서의 전기적 분석과, 표면구조분석을 시행하였다. AFM결과 Wet처리시간에 따라서 Etching형상 및 Etch rate이 영향을 받는 것이 확인되었고, Ohmic test에서 Wet chemistry처리에 의한 Tunneling parameter와 Schottky Barrier Height가 크게 증/감함을 관찰하였다. 이러한 결과들은 Wet처리에 의해서 발생된 Defect가 GaN의 표면과 하부에서 발생되며, Deep acceptor trap 및 transfer거동과 밀접한 관련이 있음을 확인 할 수 있었다. 보다 자세한 Transport 및 Wet chemical처리영향에 관한 형성 Mechanism은 후에 I-V-T, I-V, C-V, AFM결과 들을 활용하여 발표할 예정이다.

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Analysis of a Wet Surface Finned-tube Evaporator of an Air Source Heat Pump

  • Baik, Young-Jin;Chang, Young-Soo;Kim, Young-Il
    • International Journal of Air-Conditioning and Refrigeration
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    • v.10 no.4
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    • pp.211-219
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    • 2002
  • In this study, in-situ performance test of a wet surface finned-tube evaporator of an air source heat pump which has a rating capacity of 20 RT is carried out. Since test conditions, such as indoor and outdoor air conditions cannot be controlled to satisfy the standard test conditions, experiments are done with the inlet air conditions as they exist. From the experimental data, air side heat and mass transfer coefficients were calculated by the well known heat and mass transfer analogy and tube-by-tube method. Since current procedure underpredicted the experimental sensible heat factor (SHF), a proper empirical parameter was introduced to predict the experimental data with satisfactory results. This study provides the method of evaluating the heat and mass transfer coefficients of a wet surface finned-tube evaporator of which in-situ performance test is necessary.

The Experimental Study of Flux Improvement of Wet Underwater Arc Welding Electrode (습식 수중 용접봉의 피복제 개발에 관한 기초연구)

  • Kim, Min-Nam;Kang, Jung-Gun
    • Journal of Ocean Engineering and Technology
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    • v.13 no.4
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    • pp.28-36
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    • 1999
  • Wet underwater arc welding process is investigated by using experimentally developed flux coated underwater arc welding electrode and SS400 steel plate of 12mm thickness as base metal. Three kinds of different flux covered wet arc welding electrode of 4mm diameter(BK-01, BK-02, BK-03) are individually developed, and one of the improved underwater welding electrode (BK-03) may be put to practical use for underwater wet arc welding process. The results obtained from this experimental study are as follows : 1. Arc stability of developed underwater wet welding electrode is better than that of the domestic covered arc welding electrode. 2. Workability of welding electrode, remove ability of slag and bead appearances using improved underwater wet welding electrode are remarkably better than that of others. 3. Heat affected zone of test specimen welded in the underwater gets to become a lot smaller than that of test specimen welded in the air, and the maximum hardness of heat affect zone of developed underwater wet welding electrode is lower to that of domestic arc welding electrode.

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Application of WCT(Wet Compaction Test) for Fiber Evaluation

  • Seo, Yung-B.;Ha, In-Ho;Lee, Chun-Han
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.38 no.5
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    • pp.9-15
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    • 2006
  • Wet compaction test (WCT) is a fiber evaluation method where wet fibers are compressed at one side of a cylinder and water drains out from the other side. The consistency of the fiber furnishes and their pressures are recorded during the test. In the previous study we found that WCT results always gave better coefficients of determination in fiber furnish drainage, and paper properties (density, tensile, tear, and burst strength) than those of WRV (water retention value). Fiber freeness and fiber length correlated well with drainage and tear strength of the furnishes, respectively; however, their correlations were very much improved by combining the WCT results. In this study, we used the WCT test for fractionated fiber furnishes to see whether improvement of the WCT is possible. We found that strength properties such as breaking length and burst index were correlated better with the fractionated long fiber furnishes. Drainage was greatly affected by the presence of short fiber furnishes. We used bleached chemical pulps (SwBKP, HwBKP), recycled pulp (OCC), and mechanical pulp (BCTMP) as fiber furnishes in this study. Fiber fractionation can be performed on-line in these days by using multifractor and WCT can be used as an on-line test in papermachine in the future.

Development of Direct-Wet-Rice-Seedling Machines in Korea

  • Rhee, Joong-Young;Lee, Chong-Ho-
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • pp.256-266
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    • 1993
  • History , achievement and future of direct-wet-rice-seeding technique in Korea and problems encountered in on-farming research were introduced. Some farmers are very eager to lower production cost and save labor. Their effort results in several direct-wet-seeding methods and seeding machines. The design problems and improvement points related to the direct -wet-rice-seeding machines were drawn out of field test.

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In-Situ Performance Test of a Wet Surface Finned-Tube Evaporator of an Air Source Heat Pump (공랭식 열펌프의 습표면 핀-관 증발기의 현장 성능 시험)

  • 백영진;장영수;김영일
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.9
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    • pp.818-826
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    • 2001
  • In this study, in-situ performance test of a wet surface finned-tube evaporator of an air source heat pump which has a rating capacity of 20RT is carried out. Since test conditions, such as indoor and outdoor air conditions cannot be controlled to satisfy the standard test conditions, experiments are done with the inlet air conditions as they exist, From the experimental data, air side heat and mass transfer coefficients were calculated by the well known heat and mass transfer analogy and tube-by-tube method. since current procedure underpredicted the experimental sensible heat factor(SHF), a proper empirical parameter was introduced to predict the experimental data with satisfactory results. This study provides the method of evaluating the heat and mass transfer coefficients of a wet surface finned-tube evaporator of which in-situ performance test in necessary.

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The Study of Performance Evaluation Coefficient of Fin-and-Tube Heat Exchangers with Frosting (착상을 수반한 핀-관 열교환기의 성능평가계수에 관한 연구)

  • 최봉준;황준현;신종민
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.2
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    • pp.132-136
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    • 2003
  • For the study of performance evaluation on different shape heat exchangers that have the same energy consumption in a refrigerator, we make performance evaluation coefficient (PEC) which can distinguish performance of different shape heat exchangers. The results were reported in order to compare with for the dry frosting and wet frosting test as various definition of PECs. Results showed that PEC of dry frosting test is higher than that of wet frosting test because attached water droplet increases pressure drop of air-side then this decreases performance of heat exchanger.