• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.11
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• pp.1077-1084
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• 2017

Camshaft engines designed for constant engine loads have been applied to existing marine diesel engines. However, due to environmental regulations, electro-hydraulic servo mechanisms, which have a loaddependent cylinder liner jacket water cooling system (LDCL-JWCS), have been recently developed to individually control the temperature of the cylinders depending on the engine load. In this system, the 3-way valve, which prevents low temperature corrosion by reducing the temperature difference between the upper and lower parts of the cylinder, has been employed, but the outlet mass flow of the existing valve is low. In this study, the design of the internal shape of the 3-way valve was performed by analyzing the effects of the design parameters of the valve shape on the performance (i.e., the outlet mass flow rate and temperature). The proposed model was verified by comparing its performance to that of existing marine diesel engine valves.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.11
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• pp.1091-1097
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• 2017

Sales of commercial-type cooling fans intended for application in military electronics are often discontinued during equipment production. This results in requirements for alternative fan selection as well as equipment performance and reliability tests, such as high-temperature operation testing. This study deals with alternative fan selection and verification methods that can be used during the production process. First, an alternative fan was selected by calculating the flow and pressure required to effectively cool the equipment, then the feasibility of the selected fan was verified using a reliable CFD heat dissipation analysis model. Following this, a high-temperature operation test was performed using the alternative fan in the equipment. Results demonstrated that the equipment satisfied its required function in a high-temperature environment, and the main parts as well as internal air temperature were found to be thermally stable.

• Journal of KIBIM
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• v.4 no.2
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• pp.25-32
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• 2014

Today, there is a growing need of environment-friendly buildings, so-called 'green', facilities, and energy saving buildings to decrease environmental pollutants released into cities by construction activities. Green-Building Information Modeling (Green-BIM) is a purpose-built solution which supports to forecast energy consumption of 3-D model of a building by augmenting its primary 3-D measurements (width, height and depth) with many more dimensions (e.g. time, costs, social impacts and environmental consequences) throughout a series of sequential phases in the lifecycle of a building. The current study was carried out in order to integrate vegetation systems (particularly green roof and green wall systems) and investigate thermal performance of the new Sainsbury's building which will be built on Melton road, Leicester, United Kingdom. Within this scope, a 3-D building model of the news Sainsbury's building was first developed in $Autodesk^{(R)}$ $Revit^{(R)}$ and this model was then simulated in $Autodesk^{(R)}$ $Ecotect^{(R)}$once weather data of the construction site was obtained from $Autodesk^{(R)}$ Green Building $Studio^{(R)}$. This study primarily analyzed data from (1) solar radiation, (2) heat gains and losses, and (3) heating and cooling loads simulation to evaluate thermal performance of the building integrated with vegetation system or conventionally available envelops. The results showed that building integrated vegetation system can potentially reduce internal solar gains on the building rooftops by creating a 'bioshade'. Heat gains and losses through roofs and walls were markedly diminished by offering greater insulation on the building. Annual energy loads for heating and cooling were significantly reduced by vegetation more significantly through the green roof system in comparison to green wall system.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.6
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• pp.767-773
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• 2017

Infrared stealth is an important technology for naval ships. This technology helps improve the anti-detection performance and survivability of naval ships. In general, the infrared signature of naval ships are categorized into internal and external heat source. External signature are generated by ship surface heating by solar flux as well as the complicated heat transfer process with the surrounding weather condition. Modern naval ships are equipped with seawater injection nozzles on the outside for nuclear, biological and, chemical, and these nozzles are used to control external signature. Wide nozzle placement intervals and insufficient injection pressure, however, have reduced seawater dispersion area. To address this problem, nozzle installation standards must be established. In this study, an actual-scale experimental system was implemented to provide the evidence for nozzle installation standards in order to reduce the infrared signature of naval ships. In addition, the environmental conditions of the experiment were set up through computational fluid dynamics considering the ocean climate data and naval ship management conditions of South Korea. The dispersion distance was measured using a high-resolution thermography system. The flow rate, pipe pressure, and dispersion distance were analyzed, and the evidence for the installation of seawater injection nozzles and operation performance standards was suggested.

• Journal of Environmental Science International
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• v.13 no.11
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• pp.965-985
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• 2004

The investigation of driving mechanism for the formation of tropical night in the coastal region, defined as persistent high air temperature over than 25$^{\circ}C$ at night was carried out from August 14 through 15, 1995. Convective boundary layer (CBL) of a 1 km depth with big turbulent vertical diffusion coefficients is developed over the ground surface of the inland basin in the west of the mountain and near the top of the mountain, while a depth of thermal internal boundary layer (TIBL) like CBL shrunken by relatively cool sea breeze starting at 100 km off the eastern sea is less than 150 m from the coast along the eastern slope of the mountain. The TIBL extends up to the height of 1500 m parallel to upslope wind combined with valley wind and easterly sea breeze from the sea. As sensible heat flux convergences between the surface and lower atmosphere both at the top of mountain and the inland coast are much greater than on the coastal sea, sensible heat flux should be accumulated inside both the TIBL and the CBL near the mountain top and then, accumulated sensible heat flux under the influence of sea breeze circulation combined with easterly sea breeze from sea to inland and uplifted valley wind from inland to the mountain top returning down toward the eastern coastal sea surface should be transported into the coast, resulting in high air temperatures near the coastal inland. Under nighttime cooling of ground surface after sunset, mountain wind causes the daytime existed westerly wind to be an intensified westerly downslope wind and land breeze further induces it to be strong offshore wind. No sensible heat flux divergence or very small flux divergence occurs in the coast, but the flux divergences are much greater on the top of the mountain and along its eastern slope than on the coastal inland and sea surfaces. Thus, less cooling down of the coastal surface than the mountain surface and sensible heat transfer from warm pool over the coast into the coastal surface produce nocturnal high air temperature on the coastal inland surfaces, which is not much changed from daytime ones, resulting in the persistence of tropical night (nocturnal thermal high) until the early in the morning.

• Journal of the Korean Institute of Gas
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• v.16 no.2
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• pp.9-13
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• 2012

The present study has been carried out to diagnose the temperature safety of a boiler desuperheater which decreases abnormally higher temperature of superheated steam in a reheater of a power plant. The liquid water in the desuperheater stays in a closed space. It becomes heated by the high temperature superheated steam and boiling could occur. Boiling might increase internal pressure and it could destroy the desuperheater if the internal pressure exceeds the allowable pressure of the desuperheater. The present study modeled reasonably the desuperheater and four cases of heat transfer analysis are executed with the consideration of insulator and natural convective fluid flow of the inside cooling water. For the case excluded the natural convective fluid flow, the temperature exceeds the allowable temperature and pressure. On the other hand, for the real case included natural convective fluid flow and insulator, the active heat transfer from higher temperature region to lower temperature region occurs and it makes the temperature in the cooling water below the allowable temperature and pressure. From this fact, it could be thought that the desuperheater in the reheater is safe from destroy or back flow.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.96-108
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• 2015

A passive containment cooling system has been designed to remove the heat inside a containment during accidents without external power supply. In this work, the PCCS was introduced in the APR1400 plant to replace the containment spray system and, then, the thermal-hydraulic performance of the PCCS was analyzed using the system thermal-hydraulic computer code, MARS. A double-ended cold-leg break accident, which is known to induce the maximum pressure in the containment, is simulated, where the thermal hydraulics of the PCCS, the reactor coolant system, and the containment are simultaneously simulated. The results of the calculations showed that the PCCS can replace the existing spray system and that the containment building and its internal structure also play a very important role for the heat removal during the accident. Some sensitivity calculations were carried out to evaluate the model uncertainty and the effects of design parameters. The limitations of the PCCS are also discussed.

• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.818-823
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• 2015

In this study, FT reaction in a microchannel was simulated using computational fluid dynamics(CFD), and sensitivity analyses conducted to see effects of channel geometry variables, namely, process channel width, height, gap between process channel and cooling channel, and gap between process channels on the channel temperature profile. Microchannel reactor considered in the study is composed of five reaction channels with height and width ranging from 0.5 mm to 5.0 mm. Cooling surfaces is assumed to be in isothermal condition to account for the heat exchange between the surface and process channels. A gas mixture of $H_2$ and CO($H_2/CO$ molar ratio = 2) is used as a reactant and operating conditions are the following: GHSV(gas hourly space velocity) = $10000h^{-1}$, pressure = 20 bar, and temperature = 483 K. From the simulation study, it was confirmed that heat removal in an FT microchannel reactor is affected channel geometry variables. Of the channel geometry variables considered, channel height and width have significant effect on the channel temperature profile. However, gap between cooling surface and process channel, and gap between process channels have little effect. Maximum temperature in the reaction channel was found to be proportional to channel height, and not affected by the width over a particular channel width size. Therefore, microchannels with smaller channel height(about less than 2 mm) and bigger channel width (about more than 4 mm), can be attractive design for better heat removal and higher production.

• Radiation Oncology Journal
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• v.32 no.4
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• pp.256-261
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• 2014

Purpose: We performed invasive thermometry to verify the elevation of local temperature in the liver during hyperthermia. Materials and Methods: Three 40-kg pigs were used for the experiments. Under general anesthesia with ultrasonography guidance, two glass fiber-optic sensors were placed in the liver, and one was placed in the peritoneal cavity in front of the liver. Another sensor was placed on the skin surface to assess superficial cooling. Six sessions of hyperthermia were delivered using the Celsius TCS electro-hyperthermia system. The energy delivered was increased from 240 kJ to 507 kJ during the 60-minute sessions. The inter-session cooling periods were at least 30 minutes. The temperature was recorded every 5 minutes by the four sensors during hyperthermia, and the increased temperatures recorded during the consecutive sessions were analyzed. Results: As the animals were anesthetized, the baseline temperature at the start of each session decreased by $1.3^{\circ}C$ to $2.8^{\circ}C$ (median, $2.1^{\circ}C$). The mean increases in temperature measured by the intrahepatic sensors were $2.42^{\circ}C$ (95% confidence interval [CI], 1.70-3.13) and $2.67^{\circ}C$ (95% CI, 2.05-3.28) during the fifth and sixth sessions, respectively. The corresponding values for the intraperitoneal sensor were $2.10^{\circ}C$ (95% CI, 0.71-3.49) and $2.87^{\circ}C$ (1.13-4.43), respectively. Conversely, the skin temperature was not increased but rather decreased according to application of the cooling system. Conclusion: We observed mean $2.67^{\circ}C$ and $2.87^{\circ}C$ increases in temperature at the liver and peritoneal cavity, respectively, during hyperthermia. In vivo real-time thermometry is useful for directly measuring internal temperature during hyperthermia.

• Korean Journal of Food Science and Technology
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• v.41 no.3
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• pp.278-283
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• 2009

This study was carried out to evaluate the quality characteristics of white pan breads containing 0.5% of gums, including HPMC, MC and SA. Moisture content, water activity, cooling loss, bread volume, rheological, and sensory evaluations were performed to examine the bread quality characteristics. Moisture content and water activity were highest in the bread with added HPMC. HPMC showed the smallest cooling loss among the breads compared to the other added gums. The bread with added SA had the thelargest volume at $2,560{\pm}24$ mL. In terms of rheological properties, the hardness of the bread containing HPMC was lowest and the springness of the bread with added SA was the highest. In sensory evaluations, the bread containing HPMC was evaluated as the most preferred product by acquiring the highest scores in internal and external evaluations. Consequently, the bread containing 0.5% SA showed better volume and springiness values. However, the bread containing 0.5% HPMC showed greater moisture content, greater water activity, lower cooling loss, and better sensory evaluation scores. Based on the overall results, HPMC was considered to be the most effective hydrocolloid to increase bread quality.