• Monthly Duck's Village
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• s.174
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• pp.32-33
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• 2017

본 시험은 냉동 및 해동 방식에 따른 토종오리 고기의 이화학적 특성을 조사하기 위해 수행하였다. 처리구는 8주령 오리육을 대조구(Control)로 하고 처리구는 냉동방식 2가지(급냉, $-50^{\circ}C$; 완냉, $-20^{\circ}C$)과 해동방식 2가지(완해동, $4^{\circ}C$ 냉장해동; 급해동, $13^{\circ}C$ 유수해동;의 $2{\times}2$ 복합요인으로 하여 총 5처리구, 처리구당 3반복, 반복당 3점(2수/점)으로 나누었다. 공시재료는 각 처리구에서 발생된 8주령 토종오리 수컷을 처리구당 18수씩 선별하여 도압하고 1개월간 저장 후 분석에 이용하였다. 명도는 완냉시키거나 완해동할 때에 대조구와 유의적인 차이가 있었으나(P<0.05), 적색도와 황색도는 처리구간 유의차가 없었다. 가열감량과 보수력은 급냉시키거나 급해동시킬 때 대조구에 비해 유의적으로 높게 나타났으나(P<0.05), 전단력은 대조구에 비해 낮게 나타났다(P<0.05). 가열감량, 전단력, 보수력은 냉동 처리구 사이에서는 유의적인 차이를 보이지 않았으나, 가열감량은 급해동과 완해동 사이에 유의차가 나타났다(P<0.05). 수분, 지방, 단백질, 조회분의 함량은 냉동 처리구와 대조구 사이에서 유의차가 없었으나, 수분함량은 급해동 처리구에서 완해동 처리구에 비해 유의적으로 높게 나타났으며(P<0.05), 단백질 함량은 완해동 처리구에서 대조구에 비해 높게 나타났으나(P<0.05) 해동 처리구간에는 유의적인 차이가 없었다. 지방과 단백질 함량은 해동 처리구 사이에서 유의적인 차이를 보이지 않았다. 결론적으로, 본 시험에서는 냉동과 해동 방식에 따른 오리고기의 특징을 보여주고 있으며, 이런 결과들은 토종오리 산업과 오리육 생산 산업에 큰 도움이 될 것이라 사료된다.

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.678-684
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• 1998

By means of constant- pressure molecular dynamics simulations, we studied the liquid- glass- crystalline transition of a system composed of Lennard- Jones particles with periodic boundary conditions. Atomic volume and enthalpy were calculated as functions of temperature during heating and cooling processes. The Wendt- Abraham ratio derived from radial distribution function and the angular distribution function characterizing short range order were analyzed to distinguish between liquid, glass and crystalline states. A liquid phase resulting from a slow heating of an initial fee crystal amorphized on fast quench, but it crystallized on slow quench. When slowly heated, the amorphous phase from fast quench crystallized into an fee structure. A system with free surface was shown to melt from the surface inward at a lower temperature than bulk system and to have a strong tendency for crystallization even during a fast quench from a liquid state.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.144-151
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• 2010

In this study, it is investigated the mechanical chemical properties of cement matrix using phosphogypsum and kaolin as a admixture for the substitutive materials to silica fume which is so expensive. For the test, phosphogypsum is modified as dihydrate, hemihydrate, type III anhydrite, and type II anhydrite, respectively and furnaced kaolin at $900^{\circ}C$ was also manufactured into meta kaolin by air cooling and water cooling method. The chemical characteristic and mechanical properties of various type of blended cements contained above mentioned gypsum and meta kaolin materials analyzed and compared with those characteristics of cement matrix with silica fume. From the test, the cement mixed meta kaolin made in water cooling has more excellent quality than other material.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.554-560
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• 2021

CRUD (chalk river unidentified deposits) is a porous material deposited on the surface of nuclear fuel during nuclear power plant operation. The CRUD is composed of metal oxides, such as iron, nickel, and chromium. It is essential to investigate the effects of the CRUD layer on the wall heat transfer between the nuclear fuel surface and the coolant in the event of a nuclear accident. CRUD only negatively affects the temperature of the nuclear fuel due to heat resistance because the effects of the CRUD layer on two-phase boiling heat transfer are not considered. In this study, the physical property models for the porous CRUD layer were developed and implemented into the SPACE code. The effects of boiling heat transfer models on the peak cladding temperature and quenching were investigated by simulating a reflood experiment. The calculation results showed some positive effects of the CRUD layer.

• Resources Recycling
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• v.30 no.1
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• pp.83-91
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• 2021

Ladle furnace slag is a byproduct of the steel-making process, and it contains the mineral β-C2Sandtherapid-settingmineral (dependingonwhichreducingagenthasbeenused). Ladle furnace slag is often treated through slow cooling, which causes the slag to lose its reactivity. In this study, the properties of air-quenched CAC and pulverized ladle furnace slag containing gypsum were evaluated, and the optimal mixing ratio was determined for broadening their usage. Consequently, the properties of CAC aredemonstrated by the dissolution of gypsum after a period of three hours and the content of gypsum after a period of one day. The optimal mixing ratio of anhydrate and hemihydrate gypsum is found to be within 30% and that of dihydrate gypsum is found to be higher than 35%. Furthermore, based on the results of CAC with dihydrate gypsum, the applicability of the by-product dihydrate gypsum has been verified.

• Korean Journal of Poultry Science
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• v.43 no.4
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• pp.197-206
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• 2016

This work was carried out to investigate effects of the freezing/thawing method on duck meat kept in a freezer for a month. The meats used were breast muscle collected from Korean native ducks (KND) that were fed for 8 weeks (2.8 kg of live weight). Forty-five samples were used after being frozen in storage for one month and were then divided into 5 treatments (3 replications/treatment, 3 samples/replication). Five treatments (CON, FFFT, FFST, SFFT and SFST) were control groups (CON) and four were experimental groups, using $2{\times}2$ complex factors with two freezing methods (fast freezing, FF, $-50^{\circ}C$ in a deep freezer; slow freezing, SF, $-20^{\circ}C$ in a common freezer) and two thawing methods (fast thawing, FT, 5 h $12^{\circ}C$ with flow water; slow thawing, ST, 24 h $5^{\circ}C$ in a refrigerator). Lightness of KND meat in FF and FT groups was lower than that of control (P<0.05). Yellowness of KND meat of the ST group was higher than that of control (P<0.05). Cooking loss (CL) and water holding capacity (WHC) of KND meat in the control were lower than those of the freezing and thawing groups (P<0.01, P<0.05), but shear force (SF) of the control was higher than that of other groups (P<0.01). Moisture content of the ST group was higher than that of the FT group (P<0.05), and protein content of the FF group was higher than that of control (P<0.05). Stearic acid (C18:0) of the SF group was higher than that of the FF group (P<0.05). Arachidonic acid (C20:4n6) of control was higher than that of the SF and ST groups (P<0.01, P<0.05). Alanine, aspartic acid, glutamic acid, serine, and tyrosine content of the control were lower than that of the freezing and thawing groups (P<0.05). These results show that freezing and thawing methods affect meat color, shear force, cooking loss, and WHC-related water content.

• Journal of Korea Foundry Society
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• v.15 no.2
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• pp.194-200
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• 1995

Rapidly Solidified (RS) Al-Zr base splats with various alloy contents were prepared by atomization-splat quenching method to understand the continuous and discontinuous precipitation in the aged alloys. And the RS alloys were consolidated by hot extrusion and swaging to analyze the effect of plastic deformation on the precipitation behavior. Discontinuous precipitation dominated at relatively low temperature in the Al-Zr alloy, whereas both V additions to Al-Zr alloys and hot metal working appeared to suppress the discontinuous precipitation. As continuous precipitation is favored in the grain interiors, the driving force for discontinuous precipitation become to disappear with a further process.

• Journal of Korea Foundry Society
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• v.18 no.5
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• pp.462-466
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• 1998

Interest in rapid solidification of magnesium alloys stems from the fact that conventional ingot metallurgy alloys exhibit poor strength, ductility, and corrosion resistance. Such properties can be improved by microstructural refinement via rapid solidification processing. Mg-5wt%Zn alloys have been produced as continuous strips by melt overflow technique and the strips were consolidated by hot extrusion. The yield stress, tensile strengh and ductility obtained in asextruded Mg-5wt%Zn alloy were ${\sigma}_{0.2}=152\;MPa$, ${\sigma}_{T.S{\cdot}}=263\;MPa$ and ${\varepsilon}=21.8%$. In order to evaluate the influence of additional elements on mechanical properties, Th and Zr were added in rapidly solidified Mg-5wt%Zn alloy. An 130% increase in yield stress of as-extruded Mg-5wt%Zn-3wt%Th-1wt%Zr alloy was attributed to grain refinement by rapid solidification and elemental addition.

• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.3
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• pp.9-18
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• 1979

In this paper, we fabricated a samiconductor C. T. R.(Critical Temperature Resisthor) using vanadium-oxides as material and measured its electrical characteustics. Experimental results are as follows; (1) The abrupt resistance change coefficient of the fabricated C. T, R., , is approximately 3 and (2) the value of depends largely on the reducing time and quenching time and also (3) the C. T, R. with larger value of has shorter switching time.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.447-452
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• 2001

Quenching phenomena of hemispherical downward facing convex surfaces with narrow gaps have been investigated experimentally. Experiments employed test sections having 1 and 2 mm in gap thickness and 1 atm in system pressure. From interpretations of the temperature and the heat flux history, it was found that the flooding inside the gap was restricted by CCFL phenomena and quenching process was propagated from lower to upper region of the internal copper shell. The ratio of the maximum heat fluxes at 1 mm to 2mm in gap thickness was the almost same that obtained by steady state experiments. The quenching scenario of the hemispherical downward facing surface with narrow gap has been suggested.