• Journal of Advanced Marine Engineering and Technology
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• v.32 no.7
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• pp.1051-1060
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• 2008

Now days, various types of ships are operated to transport both cargo and passengers all around the world. Most of the important auxiliary machinery installed in those ships is fluid machinery such as pumps, compressors, and fans. A large percentage of fluid machinery is pumps which are classified as turbo and positive displacement pumps. This paper analyzes only turbo pumps out of the two types. This thesis has two aims: (a) to analyze the present status of pumps installed in merchant and training ships and (b) to find the correlation among sea going pump kW, port pump kW, GE kW, ME MCR, number of pumps, ME kgf, pump kgf. Based on the ship's type, my paper seeks to find special characteristics as a result of analyzing head, flow rate, and kW. Moreover this paper analyzes and compares number of pumps, rpm of pumps, pump kW/ME MCR and pump kW/GE kW under the conditions of seagoing and berthing according to the ship's type. In conclusion, (1) For the exact comparison, information on the head, kW, flow rate, number of pumps by ship's type, the pump installation status of the Merchant Ships and Training Ships were tabulated and compared in this paper. (2) In order to qualify one ship as the delegate ship, several methods were used. The result of the examination indicates that the chosen ships could be justified as a suitable representation of ships of their own type. (3) The correlation of several values(total pump kW, port pump kW, GE kW, seagoing pump kW, pump weight, ME weight, ME MCR, number of pumps and ME kW) could be obtained.

• Tribology and Lubricants
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• v.38 no.4
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• pp.162-169
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• 2022

Cobalt-chromium (CoCr)-based alloys have been used for wear applications because of their excellent mechanical properties and wear resistance. With growing concern over environmental problems, CoCr alloys are expected to be used for various tribological applications in degraded lubrication states. To expand the applicability of the materials, data should be accumulated across a broad spectrum of experimental parameters. In this work, the friction and wear characteristics of cobalt-chromium-tungsten (CoCrW) and cobalt-chromium-molybdenum (CoCrMo) alloys are investigated experimentally. The tests are conducted using a pin-on-reciprocating-plate tribotester in dry lubrication. CoCrW and CoCrMo are used as pin and plate materials to investigate the effect of the counter material. The results show that the friction coefficients between CoCrW and CoCrMo generally range from 0.4 to 0.5. The friction coefficient between the CoCrW pin and plate is found to be slightly small. However, the total wear between the CoCrW pin and plate is found to be the largest. In contrast, the total wear between the CoCrW pin and plate is relatively small. Furthermore, CoCrW may cause a faster wear progression of CoCrMo, especially for the case in which CoCrMo is used as the pin material. The results of this work provide a better understanding of the tribological properties of CoCrW and CoCrMo alloys. In addition, this work provides a practical guideline for the use of CoCrW and CoCrMo from the tribological design viewpoint.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9A
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• pp.1005-1012
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• 2004

In this paper, we have analyzed minimum performance required for W-CDMA Handset from standard and Implemented the receiver for W -COMA Handset. We have derived the noise figure and IIP3 of receiver and determined the selectivity about adjacent channel and minimum performance for front-end stage. Before the Implementation, we have verified the performance using AOS simulator In conclusion, we have implemented the receiver for W-COMA Handset using the heterodyne architecture and performed measurement. Therefore, this paper wlll gIVe a guideline for design of the W -COMA Handset.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.91-100
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• 2010

To investigate the thermal properties of a water-retentive artificial turf system (W-ATS), we estimated hydrologic parameters including thermal conductivity, heat capacity, and surface albedo for both the W-ATS and natural grass. We used a model experiment to measure surface temperature and evaporation for both the W-ATS and natural grass. We found that the W-ATS had lower thermal conductivity than natural grass did, and it was difficult for the W-ATS to convey radiant heat to the ground. Compared to natural grass, the W-ATS also had lower heat capacity, which contributed to its larger variation in surface temperature: the W-ATS had higher surface temperatures during daytime and lower surface temperatures during nighttime. The albedo of the W-ATS was one-quarter that of natural grass, and reflected shortwave radiation from the W-ATS surface was lower than that from the surface of natural grass. These results indicate that the W-ATS caused the soil temperature to increase. Furthermore, evaporation from the W-ATS was one-quarter the value of evapotranspiration from natural grass.

• Journal of the Korean Data and Information Science Society
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• v.21 no.4
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• pp.629-639
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• 2010

This paper shows that mathematics and statistics are not only a necessity but a strategic element in contributing for the competitiveness of field of S/W and H/W. First, a survey was conducted to investigate the perceived importance of mathematics and statistics to the specialists of the field. Second, computer programming was implemented in university mathematics courses to understand the educational effect related to problem solving ability. Third, a educational case in which mathematics and statistics in S/W and H/W subject were combined was analyzed. Lastly, an effective plan for mathematics and statistics education in the field of S/W and H/W will be presented.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.623-627
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• 2003

The intensity of pungency of capsicum solutions (30 Scoville Unit and 50 Scoville Unit) was decreased when a pork extract paste was mixed with the capsicum solutions. Three types of flavor enhancers, 0.5% (w/w) monosodium glutamate, 0.5% (w/w) IG (IMP : GMP = 0.5 : 0.5) and 0.5% (w/w) $Aromild^{\circledR}$ (yeast extract) decreased pungency of hot ramen soup including chilli pepper. 10% (w/w) sucrose decreased pungency of 0.66 ppm capsicum, and 0.66 ppm capsicum decreased sweetness of 10% (w/w) sucrose. Pungency of hot ramen soup was also affected by types of noodles which is boiled in the soup. The intensity of pungency of the ramen soup with fried noodles was lower than the soup with dried or fresh noodles.

• Analytical Science and Technology
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• v.15 no.1
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• pp.15-19
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• 2002

The pretreatment of tungsten added $BaTiO_x$ ceramics was performed to improve the recovery of Ba, Ti and W. $BaTiO_x$ ceramics were digested with HF : HCl ( 1 : 2 ) mixture in an acid digestion bomb at $220^{\circ}C$ for 3 hrs. The concentration of Ba, Ti and W were determined by ICP-AES. Recoveries of Ba, Ti and W were 99.6%, 99.8% and 99.2%, respectively. And their C.V. values were 1.02%, 0.73% and 1.79%. Using this method, the analytical results of Ba, Ti and W for a real sample were obainted to be 25.9% (w/w), 38.8% (w/w) and 3.31% (w/w), respectively.

• Journal of the Korean Data and Information Science Society
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• v.23 no.3
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• pp.525-534
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• 2012

The purpose of this study is to increase the employment rate of graduates in the fields of the S/W and H/W. In order to seek employment in various major fields of the S/W and H/W, firstly, this paper proposes the educational case study that increases the concern about employment and develops learner's ability in the unfavorable major fields. Secondly, this paper presents the future driving improvement for the employment rate on the basis of the department's special characteristics and the actual circumstances in the fields of the S/W and H/W. This paper conducts the surveys of each 40 seniors majoring in S/W and H/W respectively in order to measure the understanding of probability/statistics which has been used as tools in the unfavorable major fields. With the purpose of increasement on the employment rate, the paper is designed to have 3 steps, that is, a preliminary questionnaire for employment preference, major courses connecting probability/statistics and a post-questionnaire for employment preference, which eventually investigates the changes of the perception on employment. This paper is verified by the multiple regression analysis to approve the effect on improving learner's academic achievement.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.1
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• pp.24-31
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• 2004

Recently, as the marine compressor power is increased, vibration problems on the marine vessel with V/W type reciprocating compressor have been occurred. A research on the balancing of marine V/W type reciprocating compressor has hardly been reported though a number of researches on the balancing of rotating machinery have been conducted. As a V/W type compressor has high capacity with long stroke, compact size and high center of gravity, It is easy to have a vibration problem by a little bit unbalanced force and moment. In this study, calculation methods for balance weight of the V/W type reciprocating compressors, which have different piston weight and asymmetry structure, are formulated. And their reliability were verified by comparing calculated balance weight with the experimental results of the real marine V/W type reciprocating compressors.

• Korean Journal of Mathematics
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• v.23 no.4
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• pp.631-636
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• 2015

Let D be an integral domain and w be the so-called w-operation on D. In this note, we introduce the notion of *(w)-domains: D is a *(w)-domain if $(({\cap}(x_i))({\cap}(y_j)))_w={\cap}(x_iy_j)$ for all nonzero elements $x_1,{\ldots},x_m$; $y_1,{\ldots},y_n$ of D. We then show that D is a $Pr{\ddot{u}}fer$ v-multiplication domain if and only if D is a *(w)-domain and $A^{-1}$ is of finite type for all nonzero finitely generated fractional ideals A of D.