• Nuclear Engineering and Technology
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• v.32 no.2
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• pp.128-141
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• 2000

The critical heat flux (CHF）experiments have been carried out in a wide range of pressures for an internally heated vertical annulus. The experimental conditions covered ranges of pressures from 0.57 to 15.01 MPa, mass fluxes of 0 kg/$m^2$s and from 200 to 650 kg/$m^2$s, and inlet subcoolings from 85 to 413 kJ/kg. The characteristics of the present data and the effect of pressure on CHF are discussed. Most of the CHFs were identified to dryout of the liquid film in the annular or annular-mist flow. For the mass flux of 200 kg/$m^2$s, there were the indications that the CHF occurred at the transition from annular to annular-mist How in the pressure range of 3~10 MPa. For the mass fluxes of 550 and 650 kg/$m^2$s, the CHFs had a maximum value at a pressure of 2~3 MPa, and the pressure at the maximum CHF values had a trend moving toward the pressure at the peak value of pool boiling CHF as the mass flux decreased. The CHF data under a zero mass flux condition indicate that both the effects of pressure and inlet subcooling on the CHF were smaller, compared with those on the CHF with net water upward flow.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.871-875
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• 1999

This study was carried out to investigate the effects of freezing temperature on the quality of thawing aged beef loin. Drip loss was higher at 3oC freezing than at 20oC freezing, showing 17.21% drip loss after 6 days aging by 3oC freezing, 14.92% drip loss 12 days aging by 20oC freezing. Cooking loss by both water bath and pan boiling were decreased with increased in aging days. The salt soluble protein extractability of the beef loin was increased until 9 days aging by both 3oC and 20oC freezing, after that was decreased. The L value of the beef loin was high until 9 days aging by 3oC freezing, after that the L value of that was decreased. And the aging at 20oC freezing was high significantly with increased aging days. The a value of the beef loin was low significantly in 6 and 9 days aging by 3oC freezing, 20oC freezing was low significantly with increased aging days. The b value of the beginning of aging was higher with increased aging days. The percentage of denatured myoglobin of the beginning of aging was the highest, then those of 3oC and 20oC freezing showed 89.70% and 88.00%, respectively. The shear force of the beef loin was decreased with aging days, but the myofibrillar fragmentation index increased with aging days. The pH of the beef loin increased until 6 days of aging by both 3oC and 20oC freezing, after that the pH decreased.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.1
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• pp.51-60
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• 2005

This paper reviews the studies on the pressure drop and the heat transfer in microchannels. Although a lot of studies about the single-phase flow have been done until now, conflicting results are occasionally reported about flow transition from laminar flow to turbulent flow, friction factor, and Nusselt number. Some studies reported the early flow transition due to relatively greater wall effect like surface roughness, but the other studies showed that the flow transition occurred at the Reynolds number of about 2300 and the early flow transition might be due to less accurate measurement of the channel geometry. Also, there have been arguments whether the conventional relation based upon continuum theory can be applied to the fluid flow and the heat transfer in microchannels without modification or not. The studies about the two-phase flow in microchannels have been mostly about investigating the flow pattern and the pressure drop in rectangular channels using two-component, two-phase flow like air/water mixture. Some studies proposed correlations to predict two-phase flow pressure drop in microchannels. They were mostly based on Lockhart-Martinelli model with modification on C-coefficient, which was dependent on channel geometry, Reynolds number, surface tension, and so on. Others investigated the characteristics of flow boiling heat transfer in microchannels with respect to test parameters such as mass flux, heat flux, system pressure, and so on. The existing studies have not been fully satisfactory in providing consistent results about the pressure drop and the heat transfer in microchannels. Therefore, more in-depth studies should be done for understanding the fundamentals of the transport phenomena in the microchannels and giving the basic guidelines to design the micro devices.

• Korean journal of food and cookery science
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• v.31 no.5
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• pp.676-685
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• 2015

This study tried to develop Siraegi by boiling it down in soy seasoning sauce with excellent sensory attributes and evaluate the quality characteristics in order to enhance the value of traditional agricultural products, dried radish leaves. Sugar content of the seasoning sauce were finally established at 30% (w/v) compared with the starch syrup, which was added to the sauce through sensory evaluation among four groups, 0%, 30%, 60% and 100%. The texture (breaking strength) of Siraegi which was boiled for 30 minutes in water with baking powder was reduced by showing softening effect ranging from 7.6% to 42.1% as the amount of added baking powder was increased. The color of braised Siraegi produced with prepared a seasoning sauce and different content of baking powder, the brightness significantly decreased with an increase of baking powder. The reduction effects of breaking strength ranged from 25.6% to 43.9%, resulting a significant difference. The pH of braised Siraegi with a seasoning sauce significantly increased from 5.71 to 6.04 as the amount of added baking powder was increased, while its acidity was decreased. Sensory evaluation showed significant values for hardness and toughness as the values dropped when compared with the control (p<0.001), and overall acceptability of the group with adding 0.2% baking powder was best (p<0.001). In conclusion, baking powder could be considered as softening agent shorting the cooking time and improvement of the acceptability. Furthermore, it was expected that the newly developed soy sauce barised Siraegi using the dried radish leaves would be successfully utilized by side dishes in the food preparation industry.

• Journal of the Korea Concrete Institute
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• v.28 no.6
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• pp.647-653
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• 2016

In the paper, durability performance in FA (Fly Ash) blended concrete is evaluated considering replacement of FA with TDFA (Tire Derived Fuel Ash) from 3.0% to 12%. TDFA is a byproduct from combustion process in thermal power plant, where chopped rubber is mixed for boiling efficiency. This is the 1st study on application of TDFA to concrete as mineral admixture. For the work, concrete samples containing 0.5 of w/b (water to binder) ratio and 20% replacement ratio of FA are prepared. With replacing FA with TDFA to 12%, durability performance is evaluated regarding compressive strength, carbonation, chloride diffusion, and porosity. The results of compressive strength, carbonation, and porosity tests show reasonable improvement in durability performance to 12% replacement of TDFA. In particular, clear decreasing diffusion coefficient is observed with increasing TDFA replacement due to its packing effect. Concrete containing TDFA can be effective for durability improvement when workability is satisfied in mixing stage.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.2
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• pp.227-233
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• 2007

The purpose of this research was to study the effects of the feeding of dietary citrus byproducts on the physicochemical properties and palatability of Hanwoo rump (HR). The samples for experimental samples consisted of the HR not fed without citrus byproducts pulp (CBP-0) and the HR rump fed with citrus byproducts pulp during the fattening period (CBP-1). The control (CBP-0) HR rump was fed by general practical feeding (roughages and concentrates were fed separately), while the CBP-1 was fed in the same manners as CBP-0 until 17 months but with citrus byproducts then fed fer the next 10 months. There were no significant differences in the $L^*$ (tightness), $a^*$ (redness) and $b^*$ (yellowness) of the HR between the CBP-0 and CBP-1 fed groups. There were no significant differences in the pH, VBN content and EDA between the samples, but the TBARS value of the CBP-1 fed group was lower than that of the CBP-0 fed group (p<0.05). There were no significant differences in the water holding capacity, freezing loss, thawing loss, boiling and roasting logs between the CBP-0 and CBP-1 fed groups. There were no significant differences in the hardness, cohesiveness, chewiness and shear force between the samples, but the springiness of the CBP-1 fed group was higher than that of the CBP-0 fed group (p<0.05). There were no significant differences in the sensory scores for the roasted beef between the CBP-0 and CBP-1 fed groups. There were no significant differences in the taste, flavor, juiciness and palatability of roasted beef the between samples, but the tenderness of the CBP-1 fed group was superior to that of the CBP-0 fed group.

• Nuclear Engineering and Technology
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• v.37 no.6
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• pp.565-574
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• 2005

The CANFLEX Mk-V bundle is designed to improve upon the critical heat flux (CHF) characteristics of the CANFLEX Mk-IV bundle. The main difference between these two bundles is an increase in bearing pad height of about 0.3 mm in the CANFLEX Mk-IV bundle. This change in bearing pad height leads to an increase in gap flow at the bottom of the bundle, primarily eliminating the localized narrow-gap effect that limits the CHF of the CANFLEX Mk-IV bundle. The objective of this paper is to examine the effects of bearing pad height and pressure tube creep on the sheath-temperature distribution, dryout power, and dryout location, as observed ken full-scale bundle tests, between CANFLEX Mk-IV and Mk-V bundles In uncrept and crept channels. A comparison of surface-temperature differences between the top and bottom elements of the bundles showed that increasing the bearing pad height has led to a more homogeneous enthalpy distribution in subchannels of the bundle. Initial dryout locations of the CANFLEX Mk-V bundle were mainly observed at the mid-spacer plane of either the $10^{th}$ (about $80\%$) or $11^{th}$ ($20\%$) bundle in the 12-bundle string, as compared to the mid-spacer and downstream-button planes for the CANFLEX Mk-IV bundle. Dryout power and boiling-length-average (BLA) CHF values exhibit consistent trends and little scatter with varying flow conditions for both types of CANFLEX bundles in uncrept and crept channels. An increase in pressure tube creep has led to a reduction in dryout power (about $20\%$ far the $3.3\%$ crept channel and $27\%$ for the $5.1\%$ crept channel as compared to dryout powers for the uncrept channel). Increasing the bearing pad height of the CANFLEX bundle has led to an increase in the dryout power. Overall, the dryout power of the CANFLEX Mk-V bundle is 7 to $10\%$ higher than that of the CANFLEX Mk-IV bundle at the inlet temperature range of interest (i.e., between 243 and $290^{\circ}C$).

• Journal of Life Science
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• v.17 no.10
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• pp.1381-1386
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• 2007

To elucidate the changes in physiological activities of Scutellariae baicalensis by heating, composition analysis with HPLC and evaluation of physiological activities of extracts were conducted. HPLC analysis of CW(water extract at room temperature) and CHW(heat treated CW) indicated that two distinctive peaks in the HPLC chromatogram were disappeared after boiling and additional peak was newly observed. This observation suggested that certain chemical changed in the extract occurred by heat treatment. In the estimation of physiological activities, CW showed higher ACE inhibiting activity than CHW. In the case of cytotoxic activity against cancer cells, CW exhibited higher activity than CHW against CCL-185. On the other hand, CHW showed higher activity than CW against HeLa, SNU-601 and HepG2. In addition, CHW showed the inhibitory effect on melanogenesis (80% inhibition) while CW did not show any activity.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.73-80
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• 2002

Dimethyl ether (DM) is one of the most attractive alternative fuel far compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the intrinsic properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a 5-holes sac type injector (hole diameter 0.168 ㎜/hole) was performed in a high pressure chamber pressurized with nitrogen gas. A CCD camera was employed to capture time series of spray images followed by spray cone angles and penetrations of DME were characterized and compared with those of diesel. Under atmospheric pressure condition, regardless of injection pressure, spray cone angles of the DME were wider than those of diesel and penetrations were shorter due to flash boiling effect. Tip of the DME spray was farmed in mushroom like shape at atmospheric chamber pressure but it was disappeared in higher chamber pressure. On the contrary, spray characteristics of the DME became similar to that of diesel under 3MPa of chamber pressure. Hole-to-hole variation of the DME spray was lower than that of diesel in both atmospheric and 3MPa chamber pressures. At 25MPa and 40MPa of DME injection pressures, regardless of chamber pressure, intermittent DME spray was observed. It was thought that vapor lock inside the injector was generated under the two injection pressures.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.8
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• pp.82-88
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• 2008

This paper describes the influence of the bridge formed between electrodes by electrolyte for tracking process. Electrolytes is made by IEC(International Electrotechnical Commission) 60589, NaCl added to deionized water as each 1, 3, 5[wt%]. The used test equipment is made according to KS(Korean Industrial Standard) C IEC 00112. It is investigated voltage, current, value of resistance and thermal image when bridge formed between electrodes on tracking process. As a result, as conductivity of electrolyte gets bigger as Joule's heat on bridge also gets bigger. But It is not over electrolyte's boiling point due to evaporation heat of electrolyte. However as conductivity of electrolyte gets bigger as the necessary time of dry band gets shorter. So dry band is existed more long time between ahead of droplet to next droplet and discharge chance at dry band gets much. Therefore tracking process gets faster.