• Journal of the Korean Society of Visualization
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• v.6 no.2
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• pp.3-8
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• 2008

A new 3D-PTV algorithm(a Volume PTV) based upon a hybrid fitness function has been constructed. A coherency fitness function is introduced using the information of space and time to sort out the correct particle pairs between the two camera images. The measurement system consists of two-high-definition-cameras($1k{\times}1k$), a Nd-Yag laser and a host computer. The developed algorithm has been employed to investigate the flow features of the cylinder wake. The Reynolds numbers with the cylinder diameter(d=10 mm) are 360, 540, 720, 900, 1080 and 1260. Two-dimensional displacements of the particles of each camera's image and neighbouring constraints were introduced to reduce the calculation loads. More than 10,000 instantaneous 3D vectors have been obtained by the constructed algorithm. The constructed algorithm could recover more than $80{\sim}90%$ of the particle numbers in the image condition.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.6
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• pp.773-782
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• 2016

The performance of the CT-TDLAS (computed tomography-tunable diode laser absorption spectroscopy) is strongly dependent upon the line broadening functions. The line of the laser beam used in the TDLAS is scattered by the natural broadening, the collisional broadening and the doppler broadening. The influence of the natural broadening to the experimental spectra obtained in the TDLAS is negligible. The influences of the collisional broadening and the doppler broadening to the experimental spectra are relatively large, in high pressure gas flows and in high temperature low pressure gas flows, respectively. In this study, optimal coefficients are proposed for the doppler broadening function by using the experimental data obtained in a flat burner test. The optimal coefficients were ${\gamma}_j=0.16$ and n=0.37. Using these coefficients, the temperature and concentration distributions at the engine exhaust gas pipe have been calculated showing their validities.

• Journal of The Korean Society of Grassland and Forage Science
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• v.7 no.3
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• pp.153-156
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• 1987

With a purpose of evaluation rye crop as winter green feed, a cultivar was sown in autumn and harvested at booting, heading, milk, dough and yellow-ripe stages, and processed into silage. The quality of the silage was assessed in terms of ammonia-N, recovery rate in dry matter, pH, and the composition of organic acids. The results obtained are: 1. The recovery rate in dry matter from the silage was the highest when harvested at yellow stage (P<0.01). The ratio of ammonia-N to total-N was low when the rye crop was harvested during milk (9.4%) and dough ( 12.7%) stages (P$NH_3-N$. 3. Silage quality based on the composition of organic acids was highly evaluated when the crop was harvested during milk, and dough stages. 4. Considering both the DM yield and quality of the silage, it was found that rye crop should be harvested at dough stage and ensiled.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2006.05a
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• pp.98-101
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• 2006

본 연구는 사육면적에 따른 비육후기 28개월령 비거세 한우육의 냉장중 PH, 보수력, 지방산 조성 및 전자코에 의한 향기 패턴 비교를 구명하고자 실시하였다. 도축전 6개월 동안 사육면적(9, 18, 27 $m^2$)에 따라 공시하고 도축후 등심(M. longissimus) 부위를 $4{\pm}0.5^{\circ}C$에 9일 동안 저장하면서 실험하였다. pH는 저장 3일까지 27 $m^2$에서 사육한 한우육이 9, 18 $m^2$에서 사육한 한우육보다 유의적으로 높았다(p<0.05). 사후강직후 48시간의 드립 감량은 27 $m^2$에서 사육한 한우육이 9, 18 $m^2$에서 사육한 한우육보다 유의적으로 낮았다(p<0.05). 지방산 조성에서 C20:5n3(EPA)과 PUFA n3 지방산 총량은 27 $m^2$에서 사육한 한우육이 9 $m^2$에서 사육한 한우육보다 유의 적으로 높았으며(p<0.05), PUFA n6/n3 비율은 낮았다(p<0.05). 전자코의 PCA에 의한 향기 패턴은 저장기간 동안 사육면적에 따른 차이가 나타나지 않았다. 따라서 27 $m^2$에서 사육한 비거세 한우육의 보수력 및 PUFA n3 지방산 함량이 가장 높았으며, PUFA n6/n3 비율은 가장 낮았다.

• Journal of Power System Engineering
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• v.20 no.5
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• pp.29-36
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• 2016

Aluminum alloys have been widely used in engine materials, cold & hot-water storage vessels and piping etc., Furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston for various vehicles because of its properties of temperature, wear and corrosion resistance. Therefore, it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and to prolong its lifetime. In previous paper, the effect of solution($510^{\circ}C$:4hrs) and tempering($190^{\circ}C$: 16, 24, and 36 hrs)heat treatments to corrosion resistance and hardness were investigated using electrochemical method. In this study, in order to examine completely the effect of the tempering hours to hardness variation and corrosion resistance, the results of solution($510^{\circ}C$:4hrs) and tempering($190^{\circ}C$: 2, 4, 8 and 12hrs)heat treatments to hardness and corrosion resistance were investigated using electrochemical method. The hardness decreased with solution heat treatment compared to mold casting condition, but its value increased with tempering heat treatment. Furthermore, the corrosion resistance increased with decreasing of the hardness, and decreased with increasing of the hardness reversely. And the tempering heat treatment temperature at $190^{\circ}C$ for 8 hrs exhibited the highest value of the hardness and also indicated the highest corrosion current density. However, the values of hardness and corrosion current density was again increasingly decreased with increasing of tempering hours than 8 hrs, Consequently, it is suggested that decision of the optimum. tempering hours is very important to improve the corrosion or wear resistance.

• Corrosion Science and Technology
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• v.13 no.1
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• pp.15-19
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• 2014

Recently, anti-fouling paints which does not include the poison components such as tin(Sn), copper(Cu) have been increasingly developed in order to inhibit the environmental contamination of the sea water. Moreover, the wear ratios of these anti-fouling paints are very important problem to prolong their life time in economical point of view. In this study, five types of anti-fouling paints as self polishing type were investigated on the relationship between their polarization characteristics and wear ratios. It was verified that there was apparently a good relationship between the wear ratio and polarization characteristics, for example, the wear ratio increased with increasing the impedance ratio, and increased or decreased with the corrosion potential shifting in the negative or positive direction respectively. In addition, the wear ratio decreased with decreasing the corrosion current density. Consequently, it is suggested that we can qualitatively expect the wear ratio by only measuring the polarization characteristics. Therefore, before the examination of the wear ratio was actually carried out in the field, the evaluation of polarization property in the laboratory may give a available reference data for their developments.

• (The)Study of the Eastern Classic
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• no.62
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• pp.231-262
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• 2016

The Jongmyo Shrine(宗廟) of Zhou dynasty was a king's main building where a diversity of rituals were held, such as 'the assembly ceremony between a king and vassals in the morning', and was also called as Taechim(太寢) Nochim(路寢) Jeongchim(正寢) and others. Before Zhou dynasty, the expressions of Taesil(太室) and Sesil(世室) were used, and especially the term of Taesil(太室) is found in the records of the early period of West Zhou. In "Seogyeong(書經)", not only the term of Nochim(路寢) but also the letter of 'chim(寢)' itself is not found at all, but the letter of 'sil(室)' appeared several times in the chapters of "Haseo(夏書)" "Sangseo(商書)" "Juseo(周書)" except for that of "Wuseo(虞書)". "Jwajowusa(左祖右社)" meaning that 'the Jongmyo Shrine(宗廟) which keeps the late king's mortuary tablet is established in the left, and Sajikdan altar(社稷壇) which enshrines a god of land and grains is established in the right' was first mentioned in the part of 'Janginyeongguk(匠人營國 : a master craftsman builds different national infrastructures, for instance, a palace and roads)' in "Donggwangogonggi(冬官考工記)" of "Jurye(周禮)". In addition, so-called 'Jwamyowusa(左廟右社)', that is, "Sajik(社稷) enshrining the god of land and grains is built in the right('右'), and the Jongmyo Shrine(宗廟) in the left('左'). (右社稷 左宗廟)" was mentioned as one of different duties of a Sojongbaek(小宗伯) in charge of ancestral rites, which was recorded in "Chungwanjongbaek(春官宗伯)" of "Jurye(周禮)". And it seems that had affected the mention of "Jwajowusa(左祖右社)" in "Donggwangogonggi(冬官考工記)" appeared thereafter. Many manners scholars including Jeonghyun(鄭玄) since Han dynasty interpreted 'Jwa(左 : left)' and 'Wu(右 : right)' here as the arrangement relation of left and right of Jongmyo(宗廟) and Sajik(社稷), but when it is interpreted as "helping(右=佑 : to help) to sacrifice to a god of land and grains in Sajik(社稷), and helping(左=佐 : to help) memorial ceremonies in Jongmyo(宗廟)." it can correspond with a 'Jongbaek(宗伯)''s duties. 'Jeonmyohuchim(前廟後寢)' is the term that began from the expression that "what's in front is called as an jongmyo shrine(宗廟) and what's back as a bedroom.(前曰廟 後曰寢)" in Jeonghyun(鄭玄)'s annotation explaining the chapter of "Hagwansama(夏官司馬)" in "Jurye(周禮)" and "Wolryeong(月令)" in "Yegi(禮記)". Chaeong(蔡邕), a figure in the same age as Jeonghyun(鄭玄), used the expression that "a court is placed in the front, and a bedroom in the back(前有朝 後有寢)." In the paper, two hypotheses were discussed about the theory about Jeonmyohuchim(前廟後寢). In one hypothesis, it expressed two facilities within a wall; 'a court in the front to deal with governmental affairs, and a comfortable interior space in the back.' In another hypothesis, it refers to two independent and separate buildings of 'an jongmyo shrine(宗廟) building in the front as the area of governmental meetings, and the residential building in the back as the residence area with family'.

• Corrosion Science and Technology
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• v.14 no.2
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• pp.99-105
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• 2015

The structures of reinforced concrete have been extensively increased with rapid development of industrial society. Futhermore, these reinforced concretes are easy to expose to severe corrosive environments such as seawater, contaminated water, acid rain and seashore etc.. Thus, corrosion problem of steel bar embedded in concrete is very important in terms of safety and economical point of view. In this study, specimens having six different coating thickness (W/C:0.5) were prepared and immersed in flowing seawater for five years to evaluate the effect of coating thickness and immersion time on corrosion property. The polarization characteristics of these embedded steel bars were investigated using electrochemical methods such as corrosion potential, anodic polarization curve, and impedance. At the 20-day immersion, the corrosion potentials exhibited increasingly nobler values with coating thickness. However, after 5-yr. immersion their values were shifted in the negative direction, and the relationship between corrosion potential and coating thickness was not shown. Although 5-yr. immersion lowered corrosion potential, 5-yr. immersion did not increase corrosion rate. In addition, after 5-yr. immersion, the thinner cover thickness, corrosion current density was decreased with thinning coating thickness. It is due to the fact that ease incorporation of water, dissolved oxygen and chloride ion into a steel surface caused corrosion and hence, leaded to the formation of corrosion product. The corrosion product plays the role as a corrosion barrier and increases polarization resistance. The corrosion probability evaluated depending on corrosion potential may not be a good method for predicting corrosion probability. Hence, the parameters including cover thickness and passed aged years as well as corrosion potential is suggested to be considered for better assessment of corrosion probability of reinforced steel exposed to partially or fully in marine environment for long years.

• Journal of Ocean Engineering and Technology
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• v.31 no.3
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• pp.248-255
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• 2017

Many rivers and seas have been affected by environmental contamination. Therefore, city water supplies often require a high-degree purification treatment to provide safe drinking water. However, in order to achieve a high-degree purification treatment, a large amount of chlorine has to be added to sterilize city drinking water. The added chlorine reacts chemically with water and forms hypochlorous and chlorine ions. The hypochlorous ionizes with hypochlorous ions and hydrogen ions. As a result, the city water contains a large amount of chlorine ion. As such, when city water is used with domestic boilers, many kinds of heat exchangers, and the engines of vehicle and ships, there are often corrosion problems. In this study, alkali water was electrochemically made by electrolysis of city water, and corrosion properties between alkali and city water were investigated with an electrochemical method. Most of the chlorine ions are thought to not be contained in the alkali water because the alkali water is created in the cathodic chamber with an electrolysis process. In other words, the chlorine ion can be mostly removed by its migration from a cathodic chamber to an anodic chamber. Moreover, the alkali water also contains a large amount of hydroxide ion. The alkali water indicated relatively good corrosion resistance compared to the city water and the city water exhibited a local corrosion pattern due to the chlorine ion created by a high-degree purification treatment. In contrast, the alkali water showed a general corrosion pattern. Consequently, alkali water can be used with cooling water to inhibit local corrosion by chlorine ions in domestic boilers, various heat exchangers and the engine of ships and for structural steel in a marine structure.

• Journal of Ocean Engineering and Technology
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• v.28 no.4
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• pp.356-362
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• 2014

Wear and corrosion of the engine parts surrounded with combustion chamber is more serious compared to the other parts of the engine because temperature of the exhaust gas in a combustion chamber is getting higher and higher with increasing of using the heavy oil of low quality. Therefore, an optimum repair weldment as well as an available choice of the base metal for these parts are very important to prolong their lifetime in a economical point of view. It reported that there was an experimental result for repair weldment on the forged steel which would be generally used with piston crown material, however, it is considered that there is no study for the repair weldment on the cast steel of piston crown material. In this study, four types of electrodes such as 1.25Cr-0.5Mo, 0.5Mo Inconel 625 and 718 were welded with SMAW and GTAW methods on the cast steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected zone and base metal were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% $H_2SO_4$ solution. In the cases of Inconel 625, 718, the weld metals and base metals exhibited the best and worst corrosion resistance respectively, however, 1.25Cr-0.5Mo and 0.5Mo indicated that corrosion resistance of the base metal was better than the weld metal. And the weld metal welded with electrodes of Inconel 625 revealed the best corrosion resistance among the electrodes, and Inconel 718 followed the Inconel 625. Hardness relatively also indicated higher value in the weld metal compared to heat affected zone and base metal. In particular, Inconel 718 indicated the highest value of hardness compared to other electrodes in the heat affected zone.