• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.835-845
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• 1999

The objective of the present study was to investigate heat and mass transfer characteristics in a vertical falling film type absorber using LiBr-$H_2O$ solution with 6owt%. The experimental apparatus consisted of an absorber with inner diameter of 17.2 mm and length of 1150mm, a generator, an evaporator/condenser, a solution tank, a sampling trap etc. The parameters were solution temperature of 45 and $50^{\circ}C$, coolant temperature of 30 and $35^{\circ}C$, and film Reynolds numbers from 50 to 150. Pressure drop in the absorber increased as solution and coolant temperatures decreased. Pressure drop in the absorber increased up to the film Reynolds number of 90, and then decreased at the further increase of the Reynolds number above 90. The maximum absorption mass flux observed at the film Reynolds number of 90. Absorption mass flukes increased as coolant temperature decreased. Absorption mass fluxes and heat transfer coefficients under subcooled condition were larger than those under superheated condition. Heat transfer coefficients were affected by solution temperature more than coolant temperature. The maximum absorption effectiveness under the subcooled condition was 23% for coolant temperature of $30^{\circ}C$ and 31% for coolant temperature of $35^{\circ}C$ under the present experimental conditions.

• Journal of the Korean Society for Heat Treatment
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• v.32 no.4
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• pp.161-167
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• 2019

Impact toughness and fracture behavior were studied in five kinds of non-heat treating steels containing bainite; standard(0.25C-1.5Mn-0.5Cr-0.2Mo-0.15V), high V(0.3V), Ni(0.5Mn-2Ni), W(0.4W instead of Mo), and high C-Ni(0.35C-0.5Mn-2Ni) steels. The good hardness and impact toughness balance was exhibited in the $1100^{\circ}C$-rolled condition, while the impact toughness was deteriorated due to coarse grained microstructure in the $1200^{\circ}C$-rolled condition. The impact toughness decreased with increasing the hardness in all steels studied. The fracture behavior was also basically identical, that is, the fracture area was divided into 3 zones; shear and fibrous zone, fracture transition zone with ductile dimples and cleavage cracks, where the cracks initiate and grow to critical size, unstable cleavage fracture propagation zone. The energy absorbed for the critical crack formation through the plastic deformation inside the plastic zone in front of the notch root contributed to a mostly significant portion of the total impact energy.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.6
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• pp.654-661
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• 2005

Copper is a well known alloying element that is used to improve the resistance to general corrosion of stainless steel And also Cu cation have the anti-fouling effect to inhibit adhesion of the marine algae and shellfish to the surface of heat exchanger cooling pipe or outside wall of the ship, Therefore there are some anti-fouling methods such as anti-fouling Paint mixed with copper oxide or MGPS(Marine Growth Preventing System) by using Cu cation dissolved to the sea wather solution. Cu cation can be dissolved spontaneously by galvanic current due to Potential difference between Cu and cooling pipe of heat exchanger with Ti material, which may be one of the anti-fouling designs. In this study the effect of annealing heat treatment to galvanic current and Polarization behavior was investigated with a electrochemical points of view such as measurement of corrosion Potential, anodic polarization curve. cyclic voltammetric curve, galvanic current etc The grain size of the surface in annealed at $700^{\circ}C$ was the smallest than that of other annealing temperatures. and also the corrosion Potential showed more positive potential than other annealing temperatures. The galvanic current between Ti and Cu with annealed at $700^{\circ}C$ was the largest value in the case of static condition. However its value in the case of flow condition was the smallest than the other temperatures. Therefore in order to increase anti-fouling effect by Cu cation, the optimum annealing temperature in static condition of sea water is $700^{\circ}C$, however non- heat treated specimen in the case of flow condition may be desirable.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.2 s.233
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• pp.169-179
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• 2005

Nucleate boiling experiments on heating surface of constant wall temperature were performed using R113 for almost saturated pool boiling conditions. A microscale heater array and Wheatstone bridge circuits were used to maintain a constant wall temperature condition of heating surface and to measure the heat flow rate with high temporal and spatial resolutions. Bubble images during the bubble growth were taken as 5000 frames per second using a high-speed CCD camera synchronized with the heat flow rate measurements. The bubble growth behavior was analyzed using the new dimensionless parameters for each growth regions to permit comparisons with previous experimental results at the same scale. We found that the new dimensionless parameters can describe the whole growth region as initial and later (thermal) respectively. The comparisons showed good agreement in the initial and thermal growth regions. In the initial growth region including surface tension controlled, transition and inertia controlled regions as divided by Robinson and Judd, the bubble growth rate showed that the bubble radius was proportional to $t^{2/3}$ regardless of working fluids and heating conditions. And in the thermal growth region as also called asymptotic region, the bubble showed a growth rate that was proportional to $t^{1/5}$, also. Those growth rates were slower than the growth rates proposed in previous analytical analyses. The required heat flow rate for the volume change of the observed bubble was estimated to be larger than the heat flow rate measured at the wall. Heat, which is different from the instantaneous heat supplied through the heating wall, can be estimated as being transferred through the interface between bubble and liquid even with saturated pool condition. This phenomenon under a saturated pool condition needs to be analyzed and the data from this study can supply the good experimental data with the precise boundary condition (constant wall temperature).

• The Journal of the Society of Korean Medicine Diagnostics
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• v.9 no.2
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• pp.1-9
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• 2005

Background: Liu-Yuan-Lei(陸淵雷) said that a medical record is both the marks of treatments and arts made by a excellent practitioner and the essence of TCM(Traditional Chinese Medicine). Jiang-Guan(江瓘) also said that reading medical records is one of the best way to develop one’s abilities If curing a disease without perfect clinical practice. Objectives: study on the special treatment about metrostaxis(崩漏) based on the Yi-Da-Gan(易大艮)’s medical records. and study on the differentiation of abnormal symptoms and signs about cold syndrome with pesudo-heat(眞寒假熱) based on the Yu-Chang(喩昌)'s medical records. Methods: First, read and study the medical records on metrostaxis(崩漏) of that made a profound study by Yi-Da-Gan(易大艮) and cold syndrome with pesudo-heat(眞寒假熱) of that made a profound study by Yu-Chang(喩昌). The next, write a paper on results and conclusions. Results and Conclusions: First, Yi-Da-Gan(易大艮) insist that must control the Qi under the blood disease conditions, taking the case of metrostaxis(崩漏). Secondly, we must study more on estimating the changing condition of Qi and the blood as time goes by, also study on the pulse and pulse condition in the four seasons(四時脈). Thirdly, Yu-Chang(喩昌) insist that be more careful in differentiation of symptoms and signs, taking the case of cold syndrome with pesudo-heat(眞寒假熱). Fourthly, Yu-Chang(喩昌) give an example that in condition of cold syndrome with pesudo-heat(眞寒假熱), sometimes, the pulse and pulse condition can be strong.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.6
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• pp.1410-1415
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• 2008

Acupuncture and herbal treatment are based on diagnosis of cold and heat pattern in Traditional Korean Medicine. This diagnosis is accomplished through pulse, tongue and question examination, which are not objective. Quantification and objectification of this diagnosis process are required for efficacious treatment and traditional medicine development. In this study, we developed the cold-heat pattern questionnaire for this purpose. Seventy nine patients who visited oriental medical hospital were included in this study. The cold-heat pattern questionnaire was composed of many questions about patient's physical condition, which were derived from The Traditional Oriental Medical Literature with Delphi Technique. Patients filled out the cold-heat pattern questionnaire by themselves. Diagnosis of cold and heat pattern are conducted separately by oriental medical doctors with more than 5 years' clinical experience. Various physical condition factors were derived for the cold-heat pattern questionnaire. (Preference temperature, Body temperature, Pain type, Face color, Urine, Stool and secretion features) Each cold and heat symptoms group acquired internal consistency. (Cronbach's ${\alpha}$ : Cold - 0.605, Heat - 0.722) There were significant associations between doctor's diagnosis and cold symptoms in 'Aversion to cold', 'Desire for heat', 'Pale face', 'Loose stools'. (p-value < 0.05) There were significant associations between doctor's diagnosis and heat symptoms in 'Desire for cold', 'Body feverishness', 'Thirst'. (p-value < 0.05) The internal consistency results suggest that the cold-heat pattern questionnaire assured reliability. Besides, these results showed that cold-heat symptoms are apt to appear together with, and this can be indirect evidence that diagnosis of cold-heat pattern is valuable for comprehension about disease pattern. Moreover, respective symptoms of cold-heat pattern showed different significance with doctor's diagnosis. Consequently these significant symptoms can be more considered for comprehension of cold-heat pattern.

• Journal of Technologic Dentistry
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• v.17 no.1
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• pp.5-9
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• 1995

This study was carried out by obsorving to the conditions of an oxide on the surface of alloy according to the conditions of its heat treatment and analysing the change in composition on its surface. The result of this study is summarized as fellows. 1. It was shown that the higher the more the generated metal oxide while the higher the temperature of heat treatment. 2. The metal oxide was manily composed of Ni and Cr oxides. 3. The Ni composition indicated reduction while the higher the heat treatment in vaccum condition. 4. The Cr composition indicated increase while the higher the heat treatment in vaccum condition.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1247-1252
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• 2004

The present paper is devoted to the modeling method based on an averaging approach for thermal analysis of microchannel heat sinks subjected to the uniform wall temperature condition. Solutions for velocity and temperature distributions are presented using the averaging approach. When the aspect ratio of the microchannel is higher than 1, these solutions accurately evaluate thermal resistances of heat sinks. Asymptotic solutions for velocity and temperature distributions at the high-aspect-ratio limit are alsopresented by using the scale analysis. Asymptotic solutions are simple, but shown to predict thermal resistances accurately when the aspect ratio is higher than 10. The effects of the aspect ratio and the porosity on the friction factor and the Nusselt number are presented. Characteristics of the thermal resistance of microchannel heat sinks are also discussed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.971-974
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• 1987

Considering heat transfer and heat loss processes for the heat engine operating between two fixed heat reservoirs, it may be qualitatively explained that the maxima of power output and its efficiency depending upon operating conditions are extreme maxima. Furthermore, it is also found that from an economic point of view the above two extremes are related to extreme minima of plant cost per unit power output and operation cost per unit power output respectively, and the condition of minimum cost per unit power output exists between the extreme minimum conditions of plant cost per unit power output and that of operation cost per unit power output.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.107-114
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• 2016

Four cylindrically shaped IHXs(Intermediate Heat Exchangers) are installed in the PHTS(Primary Heat Transfer System) of the PGSFR(Prototype Gen IV Sodium cooled Fast Reactor). As for the IHX, the temperature difference of structure is inevitable result caused by heat transfer between primary coolant sodium and IHTS(Intermediate Heat Transport System) sodium. It is necessary to evaluate the high temperature structural integrity of IHXs which operate at the elevated temperature condition over the creep temperature. In this paper, the high temperature structural integrity of IHX under assumed loading conditions has been reviewed according to ASME code.