• Journal of the Korean Solar Energy Society
• /
• v.34 no.3
• /
• pp.82-88
• /
• 2014

Using low outdoor temperature, free cooling system is used in a data center or industrial air-conditioning for energy saving. Because use of IT equipment has increased in some office building recently, there is a growing trend towards using free cooing system. Free cooling system performance is influenced by outdoor temperature. Therefore the performance is different with regions. In this study, performance characteristic of free cooling system is analysed and energy reduction is compared with some regions. Selected regions are 4 cities; including Ulsan analyzed in preceding research, Seoul, ChunCheon and Daejeon. The Aspentech software HYSYS 8.0v was used to conduct the analysis of free cooling system based on temperature per hour of 4 cities in 2013, respectively. The main result is following as. Free cooing system in this study has energy saving effect when outdoor temperature below $7^{\circ}C$. Becuase temperature of Chuncheon is relatively low, using free cooling system can conserve most air-conditioning energy. Energy reduction amount of Seoul is 11%, Chuncheon is 17.5%, Deajeon is 15%, Ulsan is 14%. In case of large scale of air-conditioning, it is reasonable to use free cooling system although the system is used in Seoul.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.4
• /
• pp.21-32
• /
• 2002

Small and full scale model tests were performed to obtain the transient responses of shafts subjected to elastic impact by impact-echo test. Four end conditions of drilled shafts were considered: (1) free, (2) fixed, (3) rock-socketed, and (4) soft bottom. In small scale model tests, mock-up shafts were fabricated to simulate these four drilled shafts using poly-urethane and plastic material. Additionally, skin frictions between shaft and rock were changed to find out the effect of side contact on dynamic responses. All impact responses were tested in the air. Subsequently, full scale model tests were also carried out on concrete shafts that were in free and rock-socketed condition. The end conditions of the drilled shafts could be identified with good reliability by the waveforms from both small and full scale model tests. The results obtained in this study will provide an improved understanding of the impact responses for end conditions, especially for rock-socketed drilled shafts that are frequently designed and built in Korea.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.20 no.2
• /
• pp.212-218
• /
• 2008

A possible source of resonant problems in a harbor is long waves generated by incident wave groups. The analytical solutions of the governing equations of second-order long waves derived using a multiple-scale perturbation method consist of the locked and free long waves. The locked long waves propagate at some group velocity, whereas the free long waves propagate at the shallow-water speed. To study the resonance of free long waves, a trapezoidally varying topography is employed. With certain combinations of incident angle, water depth, and ambient current velocity, free long waves can be trapped and resonated.

• Archives of Reconstructive Microsurgery
• /
• v.22 no.2
• /
• pp.63-68
• /
• 2013

Purpose: In case of the failed replantation, if the patients want to preserve the length of amputated stump, toe transfer is the ideal choice. However, reconstruction of these amputated stump with a free flap can be a useful method when the patients refuse sacrificing their toe. Our purpose of this study is to evaluate availability of functional results and patient satisfaction after this procedure. Materials and Methods: From March 2008 to February 2012, we reconstructed the amputated stump with free flap by patients demand. Eleven patients were included, medial plantar artery perforator flap in seven cases and great toe pulp flap in five cases. Follow-up range 12 to 24 months and we evaluate patient satisfaction by using a visual analogue scale (VAS; 1=unsatisfied, 5=excellent) and functional recovery by measuring the range of motion of remaining joint at 12 months after operation. Results: During follow-up period, all transferred free flaps survived and no major complications were noted. Range of motion of remaining joint appeared satisfactory result ($15^{\circ}$ to $100^{\circ}$). The VAS patient satisfaction score for aesthetic were five in six patients, four in four patients, and three in one patient. Conclusion: In case of the failed digital replantation, if patient refuse toe transfer, it could be useful method to reconstruction with the free flap to preserving maximal length of amputated stump.

• Journal of the Society of Naval Architects of Korea
• /
• v.41 no.2
• /
• pp.79-89
• /
• 2004

The viscous free surface flow around KRISO container ship (KCS) is computed using the finite volume based multi block RANS code, WAVIS developed at KRISO. The free surface is captured with the Level-Set method and the realizable k-$\varepsilon$ model is employed for turbulence closure. The computations are carried out at model scale. For accurate free surface solution and its stable convergence the computations are performed with a suitable grid refinement around the free surface by applying an implicit discretization method based on a finite volume method to the Level-Set formulation. In all computational cases the numerical results agree well with experimental measurements.

• Quality Improvement in Health Care
• /
• v.5 no.1
• /
• pp.2-14
• /
• 1998

The aim of this study was to examine differences in the level of satisfaction with medical care at a public health center between patients receiving free-care compared to those paying out-of-pocket. SERVQUAL(Comprehensive Service Quality Measurement Scale), a pyschometrically valid measure for evaluating hospital service quality, was used to assess patient satisfaction. The study sample consisted of 279 patients who received medical care at a public health center. The interview was conducted between April 23 and May 7, 1998. The results was as follow: 1. There were more elderly people among free-care patients than out-of-pocket patients. Education and income levels were lower amongs those receiving free-care. There were, however, no differences in the distribution of gender and religion between the two groups. Patients receiving free-care tended to visit the public health center more frequently compared to those self-paying patients. 2. Overall, free-care patients showed higher satisfaction level than that of self-paying patients. except for the dimension on sympathy and shape.

• Journal of the Society of Naval Architects of Korea
• /
• v.59 no.5
• /
• pp.288-295
• /
• 2022

In this study, the force and moment acting on a Joubert BB2 submarine model at depths near the free surface were measured through a captive model test with the scale ratio of 1/15. Based on the experiment, the pitch moment and heave force due to the "Tail suction effect", including the change in surge force with depth near the free surface, were quantitatively analyzed. The change of force and moment according to the relative position of the sail and the free surface was reviewed with the free surface waves generated for each depths. As a result, the angle of attack of the hull to counteract the pitch moment induced by the tail suction effect was derived. The effect of the hydrostatic moment component according to the angle of attack on the equilibrium of pitch moment was also taken into account. The control plane performance tests for the X-type rudder and sail plane were conducted in snorkel and surface depth conditions to figure out the control plane angles for the neutral level flight of the submarine at near free surface. The results of this study are expected to be used as a reference data for the neutral level flight of the submarine at near free surface operation in the free running model test as well as numerical studies.

• Journal of the Korean Magnetic Resonance Society
• /
• v.22 no.1
• /
• pp.18-25
• /
• 2018

Replication protein A (RPA) is an essential single-stranded DNA binding protein in DNA processing. It is known that N terminal domain of RPA70 (RPA70N) recruits various protein partners including damage-response proteins such as p53, ATRIP, Rad9, and MRE11. Although the common binding residues of RPA70N were revealed, dynamic properties of the protein are not studied yet. In this study, we measured $^{15}N$ relaxation parameters ($T_1,\;T_2$ and heteronuclear NOE) of human RPA70N and analyzed them using model-free analysis. Our data showed that the two loops near the binding site experience fast time scale motion while the binding site does not. It suggests that the protein binding surface of RPA70N is mostly rigid for minimizing entropy cost of binding and the loops can experience conformational changes.

• The KSFM Journal of Fluid Machinery
• /
• v.10 no.4
• /
• pp.39-46
• /
• 2007

In large pump station, vortex generation such as free-surface vortex and submerged vortex occurring around pump intake, or at bell-mouth inlet has been an important flow characteristics which should be considered always to keep away the suction of air-entrained or cavitated flow. In this study, a commercial CFD code was used to predict accurately the vortex generation for the specified intake design. These result shows the preliminary result of submerged vortex prediction for the Turbo-machinery Society of Japan Sump Test CFD standard model. At bottom wall, air volume fraction (red color) was found in a large scale to explain the submerged vortex generation at particular operation and configuration condition. And these indicate the free surface formation behind the bell mouth. Particularly, non-uniform approaching flow is a major parameter to govern the occurrence of the free-surface vortex. Futhermore the comparison between turbulence ($k-{\epsilon}$ & $k-{\omega}$ model) mode were executed in this study.

• Transactions of Materials Processing
• /
• v.6 no.3
• /
• pp.203-212
• /
• 1997

In this research, to obtain the optimal die width of CV die(conventional die), which replaces FM die in free forging of large scale rotor using the flat die, the model material experiments and theoretical analysis using three dimensional FEM are performed. The FM die, which was designed to remove Mannesmann's effect at the central part of the ingot, has very bad workabiltity in real field, therefore on the empirical base they use the CV die of wide width in actual working field. In this study, the excellency of CV die is proved quantitively, and the optimal die width of CV die is determined through the model material experiments and theoretical analysis using FEM in the point of effective strain, stresses, and load.