• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.4
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• pp.238-244
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• 2008

This study investigates on the improvement of inhalation effect of hood which attached new device named as "gas-guide-device" in local exhaust ventilation system for the effective elimination of harmful material and dust in manufacturing factory. The gas-guide-device having a diamond shape is composed of width (b) and two sides of a device (X, Y) and its size is selected the industrial hood under application in manufacturing factory after due consideration. In order to investigate the effect of gas-guide-device, numerical and experimental study is performed that the flow velocity is calculated and is measured by a commercial program "COMSOL $Multiphysics^{TM}$" and a hot wire type of anemometer, respectively. The numerical and experimental results are revealed is a similar pattern and flow velocity has improved to hood attached gas-guide-device. Also, the numerical method and result is also verified the dependance. Moreover, the optimum shape and size of gas-guide-device is revealed that the width (b) and the ratio of two sides of gas-guide-device (X, Y) has 125mm and 4 to 6.

• Bulletin of the Korean Chemical Society
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• v.21 no.4
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• pp.393-400
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• 2000

2,2￠-Dihydroxyazobenzene (DHAB) was attached to poly(ethylenimine) (PEI) to obtain DHAB-PEI. Spectral titration revealed that uranyl, Fe(III), Cu(II), and Zn(II) ion form 1 : 1-type complexes with DHAB attached to PEI. Formation constants for the metal complexes formed by the DHAB moieties of DHAB-PEI were mea-sured by using various competing ligands. The results indicated thatthe concentrations of uranyl, Fe(III), and Cu(II) ions can be reduced to 10 -16 -10 -23 M at p 8 with DHAB-PEI when the concentration of the DHAB moiety is 1 residue M. By using cyanuric chloride as the coupling reagent, DHAB-PEI was immobilized on Sephadex G-25 resin to obtain DHAB-PEI-Seph. Binding of uranyl,Fe(III), Cu(II), and Zn(II) ion by DHAB-PEI-Seph was characterized by using competing ligands. A new method has been developed for characteriza-tion of metal sequestering ability of a chelating resin. Formation constants and metal-binding capacity of two sets of binding sites on the resin were estimated for each metal ion. DHAB-PI-Seph was applied to recovery of metals such as uranium,Fe, Cu, Zn, Pb, V, Mn, and W from seawater. The uranium recovery from seawaterby DHAB-PEI-Seph does not meet the criterion for economical feasibility partlydue to interference by Fe and Zn ions. The seawater used in the experiment was contaminated by Fe and Zn and, therefore, the efficiency of uranium extractionfrom seawater with DHAB-PEI-Seph could be improved if the experiment is carried out in a cleaner sea.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1518-1528
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• 1995

The deformation and departure processes of a bubble attached to the wall are studied experimentally and numerically to understand the phenomena of the nucleate boiling heat transfer enhancement under DC electric field. An air-bubble is injected in a dielectric liquid with different electric fields generated by changing three types of electrode system (Type 1,2 and 3) in the bubble generator. Experimental variables are the electric field strength and the distance and the shape of the electrodes under DC electric field. From experimental results, it is observed that the bubble under Dc electric field is elongated in the same direction as the electric field and the contact angle increases. For the parallel plate electrode which generates a uniform electric field, bubble departure volume doesn't seem to decrease within our experimental range. However, when a needle is raised a few millimeters from the lower electrode to make a nonuniform electric field around the needle, bubble departure volume decreases continuously with the increase of an applied voltage. The reduction effect of bubble departure volume is the most effective under a strong nonuniform electric field generated with Type 3. As the nonuniformity of the electric field due to the shape of a electrode increases, the terminal velocity and the acceleration of a bubble increase largely. For the comparison with visualization results, the deformation of a bubble attached to the electrode is carried out by a numerical method. Numerical results show good agreement qualitatively with experimental results.

• Journal of Biomedical Engineering Research
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• v.30 no.1
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• pp.23-33
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• 2009

It can be used easily to reduce rehabilitation and treatment time if diagnostic and therapeutic devices are attached to cloth or body. Therefore we developed neuromuscular wearable ultra-miniature lighting modules which can improve the neuromuscular function and verified its clinical effectiveness. The system is based on the ultra-miniature lighting treatment module and there are two types of systems. One of them is designed as an attached type and the other type is combined with clothing. The wearable ultra-miniature lighting module is composed of controller (battery, MCU, bidirectional transmitter and receiver), cable, treatment medium generating device and other peripheral devices. To verify the clinical effectiveness of this device, we observed the difference of the strength of a muscle before and after 650nm and 25mW laser irradiation on the reflex point for 1 to 4 seconds. Among 48 patients having the degenerative osteoarthritis, the muscle strength before and after irradiation of laser was $21.8{\pm}7.99$ and $27.3{\pm}8.43$. According to the result, the muscle strength after treatment was significantly increased (p<0.01). To whom having difficulty in visiting to OPD(Out-Patient Department), doctors medically examine the patients and find the therapeutic point, attachment of this wearable ultra-miniature lighting module can function as self treatment (treating instrument) and treatment assist at home. If doctor can remotely control the patient and take part in treatment, the therapeutic device could contribute to prevention and care device.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.9
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• pp.706-715
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• 2014

Recently, the medical community has been enthusiastically welcoming robots that are able to provide high-quality medical services across the board, including assisting the surgeons during surgeries. In response, many higher education institutions and research facilities started to conduct various experiments and studies about these robots. During such research, it was discovered that the arm of one particular robot type that is being developed to assist surgeries are prone to vibrate even from the weakest impact, in addition to other residual vibration problems. We attempted to reduce such dynamic response by using a MF-TMD that is produced by adding magnetic fluid to ECD. We verified the MF-TMD's performance by testing it within various frequency bands and attenuations. We then designed a cantilever that was structurally similar to the robot's arm. We attached the MF-TMD to this cantilever and conducted a pilot experiment, which validated our hypothesis that MF-TMD will reduce the robot arm's vibrations through its optimal damping ratio. Henceforth, we attached the MF-TMD to the robot arm in question and conducted a performance experiment in which we tuned the MF-TMD's frequency and damping factor to its optimal level and measured the vibrations of the arm. The experiment demonstrated that the vibrations that occurred whenever the arms rotated were significantly reduced.

• Journal of Korean Society of Steel Construction
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• v.16 no.1 s.68
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• pp.169-180
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• 2004

One of the most influential elements is the moment resisting beam-to-column connection vis-a-vis the behavior and cost of multistory steel building frames. Majority of these connections are column flange connections attached to beam frames. This is called strong-axis connection. Another type of moment resisting connection commonly found in building frames is the web axis connection. In this type of connection, the beams are attached to the plane of the column web perpendicularly. It is called the weak-axis beam. and it tends to bend the column at its weak axis. In this study, some of the fundamental behaviors of beam-to-column connections were examined by changing the connection details as weil as comparing them with previous connection details. This study sought to develop the details in the beam-to-column connection in the weak axis for middle- and low-rise steel construction systems.

• KSBB Journal
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• v.29 no.3
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• pp.183-187
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• 2014

Sick-building syndrome occurs when indoor air is polluted with harmful volatile organic compounds such as formaldehyde which are contained in furniture or new building materials. In this study, formaldehyde-shielding chitosangel sheet was developed and its performance was evaluated. Chitosan and agar were dissolved in acetic acid solution. The optimal concentrations of chitosan, acetic acid and agar were 3, 3, and 2.5 %(w/w). Formaldehyde was spreaded on gypsum board and then wall paper was attached on it by using glue. When chitosan-gel sheet was attached on this control board, the amount of formaldehyde released from the board was decreased by 63% than in control board. On the other hand, decrease in formaldehyde releasing was only 32% when liquid solution of chitosan was spreaded on the control board. This result clearly indicates that chitosan-gel sheet removes formaldehyde more effectively than liqud solution of chitosan. Furthermore, this type of sheet is more applicable to new building than spraying type.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.23-28
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• 1972

The following results were obtained from the experiment on the oyster spatfall, Crassostrea gigas by means of the rack method in YonghoBay, on the southern coast of Korea, from June to August in 1962 and 1963. 1. The Outside of shells as a collector showed better result than inside in numbers of attached oyster spats. 2. The horizontal type of the rack was more efficient for spatfall than the typical type of the rack. 3. The mode variance, in shell height, were shown as 21-25mm and 26-30mm, and the variance of range was 13.0-53.0mm for 77 days. 4. The optimum spat-fall season was from August 17 to 19 and 24 to 27, and spat of the oyster were attached in number of 7 per collector each day. 5. The optimum exposure time in spatfall was 4 hours. 6, The average water temperature and specific gravity, during the spawning season, was $25.98^{\circ}C$ and 0.1871, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.6
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• pp.734-743
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• 1999

The local Nusselt numbers have been measured for a round turbulent jet impinging on the concave surface with and without rib. Liquid crystal/transient method was used to determine the Nusselt number distributions along the surface. The temperature on the surface was measured using liquid crystal and a digital color image processing system. The experiments were made for the jet Reynolds number (Re) 23,000, the dimensionless nozzle-to-surface distance (L/d) from 4 to 10, the dimensionless surface curvature (d/D) 0.056, and the rib type (height ($d_1$) 0.2 cm, pitch (p) from 1.2 to 3.2 cm). It was founded that only when $L/d{\geq}6$, the average Nusselt numbers on the concave surface with rib are higher than those without rib, mainly due to an increase in the turbulent intensity caused by the effect of rib attached to the wall surface. It was realized that the rib attached to the concave surface may no longer enhance the heat transfer rate or even lowers it depending on the rib type and flow conditions. In addition, the results by the steady-state method using the gold-film Intrex were in good agreement with those by the transient shroud method.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.290-298
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• 2016

This study aims to reduce the force exerted to the buoy of the gillnet by wave and current. Five buoy models were selected for experiments and their rope tensions under wave and current action were compared. Five models were EL (ellipsoid), EL-H (ellipsoid-hole), SL (streamlined body), SP (sphere) and CL (cylinder, traditional type). In the first experiment, the Five models were tested without any attachment. In the second experiment, a flagpole was attached to each model. As a result, in the condition without flagpole, the tensions of four models with the exception of the CL were about a half of that of the CL. In the condition with flagpole, the tension of all models was twice larger than that without flagpole. Thus, a new model was suggested to improve the problem, which has a combined body that of a flagpole and a buoy Three new models of CL-L (long and thin cylinder), LF (leaf shape) and LF-F (leaf shape with fin) were designed. Also a cylinder type (CLD) with a flagpole as a control was included in the experiment. As a result, the LF-F had the smallest tension and a half tension of the CLD. Therefore, it is supposed that the flagpole and buoy combined model could reduce the tension on buoy rope and contribute to improve the gillnet loss problem.