• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.1 s.244
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• pp.24-31
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• 2006

Mixing vanes have been installed in the space grid of nuclear fuel rod bundle to improve turbulent heat transfer. Split mixing vanes induce the vortex flow in the cooling water to swirl in sub-channel of fuel assembly. But, The swirling flow decays rapidly so that the heat transfer enhancing effect limited to short length after the mixing vane. In thi present study, the large scale vortex flow(LSVF) is generated by rearranging the mixing vanes to the coordinated directions. This LSVF mixing vanes generate the most strong secondary flow vortices which maintain about 35 $D_H$ after the spacer grid. The streamwise vorticity generated by LSVF sustain two times more than that split mixing vane. Heat transfer in the rod bundle occurs greatly at the same direction to cross flow, and maximum temperature at the surface of bundle drops about 1.5K

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.3
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• pp.311-318
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• 2003

The present work evaluates the effects of mixing vane shape on the flow structure and heat transfer downstream of mixing vane in a subchannel of fuel assembly. by obtaining velocity and pressure fields. turbulent intensity. flow-mixing factors. heat transfer coefficient and friction factor using three-dimensional RANS analysis. Four different shapes of mixing vane. which were designed by the authors were tested to evaluate the performances in enhancing the heat transfer. Standard k-$\varepsilon$ model is used as a turbulence closure model. and. periodic and symmetry conditions are set as boundary conditions. The flow blockage ratio is kept constant. but the twist angle of mixing vane is changed. The results with three turbulence models were compared with experimental data.

• Solar Energy
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• v.20 no.3
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• pp.75-84
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• 2000

The purpose of this research is to study on the heat transfer characteristics of separate type heat pipe with a rotor. The heat transfer characteristics of the rotor condenser are various on input heat of evaporator, rotational speeds of rotor, and working fluid amount. The results obtained from the study are as follows. 1. Magnetic fluid using seal of the rotor operated in stability by a variation of temperature and rotation speeds. The configuration of magnetic fluid seal assembly was adequate. 2. Steam ejector is effective in recovering working fluid condensate in the rotor. When steam ejector is operating, the heat flux of working fluid does not change, with the wall temperature in the rotor. 3. The optimum design conditions on working fluid amount and rotational speeds are effective in evaporator volume 50%, rotational speeds 200rpm, 300rpm, and operating temperature $80^{\circ}C$. With working fluid amount increasing, overall heat transfer coefficient decreases linearly.

• Journal of Life Science
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• v.15 no.4 s.71
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• pp.613-618
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• 2005

We investigated the effect of chicory (Chicorium intybus) extract on triglyceride concentration and microsomal triglyceride transfer protein (MTP) activity in rats. The effect of water-soluble extract of chicory fed at the $2.0\%\;and\;4.0\%(w/w)$ levels for 2 weeks on the concentration of serum triglyceride and the activity of hepatic microsomal riglyceride transfer protein (MTP) was investigated in male Sprague-Dawley rats. The triglyceride concentrations in serum of the chicory extract fed groups were significantly lower than in the control group. MTP activity, known to be essential for the assembly/secretion of apolipoprotein B-containing lipoproteins, was also significantly lower in the chicory extract groups than in the control group. The concentrations of other lipids in serum and liver and the activity of phosphatidate phosphohydrolase, the rate-limiting enzyme in triglyceride synthesis, showed no significant differences among in the chicory fed groups. These results indicate that dietary chicory extract decrease hepatic MTP activity and serum triglyceride concentration, and therefore reduces hepatic lipoprotein assembly and secretion.

• 대한생식의학회:학술대회논문집
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• 2001.11a
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• pp.89.2-89.2
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• 2001

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.409-412
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• 2009

A 75ton thrust turbopump system for liquid rocket engine was analyzed thermally and mechanically. A 2D axisymmetric model of the turbopump assembly was created. In the analysis operation cycle including chill-down, operation and post operation steps were considered. Appropriate heat transfer conditions for each step were modeled and applied. Transient temperature distribution was calculated, consequent mechanical analysis was conducted to predict stress and deformation. Effects of external heat insulators and heat dissipation at the bearings were considered in the heat transfer analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.5
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• pp.113-117
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• 2011

The frame for automotive assembly can be deformed and remained on the residual stress due to high temperature thermal attacks when in welding. The frame deformation can be made to problems when in assembly with body and the residual stress can affect the negative effect on durability performance of the automobile. In order to analyze the frame deformation, the simplified test frame which had the similar shape (form) of the real automotive frame was fabricated. The contactless optical 3D scanner was used for the shape difference measurement of the frame between before and after the welding. The FE-model of the test frame was composed and the heat transfer and thermal stress simulation were performed. The simulated results were compared with the measured results for the reference of the frame design. The deformation shape of the frame by simulation was in good agreement with that by the experimental measurement.

• The Korean Journal of Archival Studies
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• no.55
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• pp.39-71
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• 2018

The purpose of this study is to examine the reality of the records management of the National Assembly members and suggest a desirable alternative. Until the Public Records Management Act was enacted in 1999, the level of the records management in the National Assembly was not beyond that of the document management in both the administration and the legislature. Rather, the National Assembly has maintained a records management tradition that systematically manages the minutes and bills since the Constitutional Assembly. After the Act was legislated in 2000, the National Assembly Records Management Regulation was enacted and enforced, and the Archives was established in the form of a subsidiary organ of the Secretariat of the National Assembly, even though its establishment is not obligatory. In addition, for the first time, an archivist was assigned as a records and archives researcher in Korea, whose role is to respond quickly in accordance with the records schedule of the National Assembly, making its service faster than that of the administration. However, the power of the records management of the National Assembly Archives at the time of the Secretariat of the National Assembly was greatly reduced, so the revision of the regulations in accordance with the revised Act in 2007 was not completed until 2011. In the case of the National Assembly, the direct influence of the executive branch was insignificant. As the National Assembly had little direct influence on the administration, it had little positive influence on records management innovation under Roh Moo-Hyun Administration. Even within the National Assembly, the records management observed by its members is insignificant both in practice and in theory. As the National Assembly members are excluded from the Act, there is no legal basis to enforce a records management method upon them. In this study, we analyze the records management problem of the National Assembly members, which mainly concerns the National Assembly records management plan established in the National Archives. Moreover, this study proposes three kinds of records management methods for the National Assembly members, namely, the legislation and revision of regulations, the records management consulting of the National Assembly members, and the transfer of the dataset of administrative information systems and websites.

• Nuclear Engineering and Technology
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• v.47 no.7
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• pp.814-826
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• 2015

The most important advantage of nanoparticles is the increased thermal conductivity coefficient and convection heat transfer coefficient so that, as a result of using a 1.5% volume concentration of nanoparticles, the thermal conductivity coefficient would increase by about twice. In this paper, the effects of a nanofluid ($TiO_2$/water) on heat transfer characteristics such as the thermal conductivity coefficient, heat transfer coefficient, fuel clad, and fuel center temperatures in a VVER-1000 nuclear reactor are investigated. To this end, the cell equivalent of a fuel rod and its surrounding coolant fluid were obtained in the hexagonal fuel assembly of a VVER-1000 reactor. Then, a fuel rod was simulated in the hot channel using Computational Fluid Dynamics (CFD) simulation codes and thermohydraulic calculations (maximum fuel temperature, fluid outlet, Minimum Departure from Nucleate Boiling Ratio (MDNBR), etc.) were performed and compared with a VVER-1000 reactor without nanoparticles. One of the most important results of the analysis was that heat transfer and the thermal conductivity coefficient increased, and usage of the nanofluid reduced MDNBR.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.3
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• pp.241-252
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• 2024

With the recent development of emerging technologies, information acquisition and delivery between users has been actively conducted, and inorganic thin film transfer technology that effectively transfers various materials and devices is being studied to develop flexible electronic devices accordingly. This is aimed at innovative structural changes and functional improvement of electronic devices in the era of the Internet of Things (IoT). In particular, advanced technologies such as microLEDs are used to realize high-resolution flexible displays, and the possibility of heterogeneous integrated technologies can be presented by precisely transferring materials to substrates through various transfer process. This paper introduced physical, chemical, and self-assembly transfer methods based on inorganic thin film materials to implement heterogeneous integrated flexible semiconductor systems and introduces the results of application studies of semiconductor devices obtained through different transfer technologies. These studies are expected to bring about innovative changes in the field of smart devices, medical technology, and user interfaces in the future.