• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.266-269
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• 1999

Several power factor correction(PFC) circuits are presented to achieve high PF electronic ballast for both voltage-fed and current-fed electronic ballast. The proposed PFC circuits use valley-fill(VF) type DC-link stages modified from the conventional VF circuit to adopt the charge pumping method for PFC operations during the valley intervals. In voltage-fed ballast, charge pump capacitors are connected with the resonant capacitors. In current-fed type, the charge pump capacitors are connected with the additional secondary-side of the power transformer. The measured PF and THD are higher than 0.99 and 15% for all proposed PFC circuits. The lamp current CF is also acceptable in the proposed circuits. The proposed circuit is suitable for implementing cost-effective electronic ballast.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.125-130
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• 2008

The present study numerically simulates the flow and heat transfer characteristics of rib-induced secondary flow in a cooling channel with staggered V-shaped ribs, extruded on both walls. The rib pitch-to-height ratio (p/h) varies from 2.8 to 10 with the rib-height-to-hydraulic diameter ration ($h/D_h$) of 0.07 and the Reynolds number of 50,000. Shear stress transport (SST) turbulence model is used as a turbulence model. Computational results show that complex secondary flow patterns are generated in the duct due to the snaking flow in the streamwise direction for all tested cases. In the range of p/h=5 to 10 the staggered V-shaped rib gives about 3 times higher heat transfer augmentation than the reference smooth channel with high heat transfer on both front side and the area around the leading edge of the ribs, while the former cases give about 2.5 times higher streamwise pressure drop than the latter ones. Consequently, for the thermal performances, based on the equal pumping power condition, the staggered ones give about 2 times higher values than the latter ones with more uniform heat transfer distribution.

• Journal of Mechanical Science and Technology
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• v.18 no.2
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• pp.313-324
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• 2004

A rich phenomenon in the dynamics of azimuthal vortices in a circular cylinder caused by the inertial oscillation is investigated numerically at high Reynolds numbers and moderate Rossby numbers. In the actual spin-up flow where both the Ekman circulation and the bottom friction effects are included, the first appearance of a seed vortex is generated by the Ekman boundary-layer on the bottom wall and the subsequent roll-up near the corner bounded by the side wall. The existence of the small vortex then rapidly propagates toward the inviscid region and induces a complicated pattern in the distribution of azimuthal vorticity, i.e. inertial oscillation. The inertial oscillation however does not deteriorate the classical Ekman-pumping model in the time scale larger than that of the oscillatory motion. Motions of single vortex and a pair of vortices are further investigated under a slip boundary-condition on the solid walls. For the case of single vortex, repeated change of the vorticity sign is observed together with typical propagation of inertial waves. For the case of a pair of vortices with a two-step profile in the initial azimuthal velocity, the vortices' movement toward the outer region is resisted by the crescent-shape vortices surrounding the pair. After touching the border between the core and outer regions, the pair vortices weaken very fast.

• CELLMED
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• v.5 no.2
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• pp.10.1-10.3
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• 2015

Arthritis is a major cause of joint pain, stiffness, and subsequent disability which adversely affects quality of life. Seriously, it can lead to long term social and psychological effects including loss of independence, depression, and anxiety. Arthritis is usually treated with joint replacement surgery or medications. However, the artificial joint is temporary and pharmacological measures have side effects, such as addiction or hypersensitivity. Thus, orthotics has been developed to improve arthritis as a nonpharmacological measure. The increased regional load across compartments of articular cartilage is an important factor in the cause of the arthritis. Mubal$^{(R)}$, a clinical shoe insole, has a sliding function to help people to walk straight and realign the body balance. The slide of Mubal$^{(R)}$ reduces the knee joint loading in patients with arthritis. In addition, pumping function of Mubal$^{(R)}$ can mitigate arthritis by stretching the squashed nerves from lumbar to cervical vertebral and actively circulating blood of pelvic limb. In addition, Mubal$^{(R)}$ could help to stimulate the growth plate. Therefore, Mubal$^{(R)}$ can be used for the child with short stature as well as patients with arthritis.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.515-522
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• 1999

Several power factor correction(PFC) circuits are presented to achieve high PF electronic ballast for both v voltage-fed and current-f,어 ek'Ctronic ballast. The proposed PFC circuits use valley-fil[(VF) type DClink s stages modified from the conventional VF circuit to adopt the charge pumping method for PFC operations d during the valley intervals. In voltage-fed ballast, charge pump capacitors are connected with the resonant c capaCltor In current-fed type, the charge pump capacitors are connc'Ctc'Cl with the additional second따y-side of t the power transformer. The measured PF is higher than 0.99 and THD is about 10% for all proposed PFC c circuits. The lamp current CF is also acceptable in the proposed circuits. The proposed circuit is suitable for i implementing cost longrightarroweffective electronic ballast.

• Korean Journal of Metals and Materials
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• v.49 no.9
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• pp.708-714
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• 2011

The premature failure of a servovalve used for six months in a thermal power plant has been analyzed. The servovalve was made of stainless steel, containing 16Cr-0.44Mo, along with other elements. An overload of oil-supply pumping and an abnormal increase in the oil flux were observed during operation. A study revealed that erosion and corrosion could be the main causes of the failure. The visual examination of the servovalve did not show any appreciable damage. However, corrosion and erosion of the servovalve were observed using scanning electron microscopy (SEM). Upon examination of the servovalve, the corrosion was found to have occurred throughout the bushing and spool; however, erosion occurred at only the edge-side. In addition, the condition of the electrohydraulic control system (EHC) oil was investigated with respect to its satisfaction of the management standard.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.9
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• pp.4037-4040
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• 2015

Objective: To explore the clinical efficacy and toxic and side effects of recombinant human endostatin (rhendostatin/endostar) combined with chemotherapy in the treatment of advanced gastric cancer. Materials and Methods: A total of 70 patients with advanced gastrointestinal adenocarcioma confirmed by histopathology and/or cytological examination were divided into group A (37 patients) and group B (33 patients). Patients in group A were given intravenous drip of 15 mg endostar added into 500 mL normal saline, once every other day until the cessation of chemotherapy or patients' maximal tolerance to chemotherapy. Patients in group B received chemotherapy alone. Two groups selected the same chemotherapy regimens. FOLFIRI scheme: 90-min intravenous drip of $180mg/m^2$ irinotecan, intravenous drip of $200mg/m^2$ calcium folinate (CF) and $400mg/m^2$ 5-fluorouracil (5-Fu) on d1, and continuous intravenous pumping of 2 $400mg/m^2$ 5-Fu for 46 h. FOLFOX4 scheme: intravenous injection of $85mg/m^2$ oxaliplatin (L-OHP), $200mg/m^2$ calcium folinate (CF) and $400mg/m^2$ 5-FU on d1 for 2 h, and then continuous intravenous pumping of 2 $400mg/m^2$ 5-Fu for 46 h. XELOX scheme: oral administration of 1 $500mg/m^2$ xeloda (or tegafur 50~60 mg) in twice during d1~14 and intravenous drip of $135mg/m^2$ L-OHP on d1 for 2 h. The modified FOLFOX scheme: intravenous injection of $135mg/m^2$ L-OHP on d1 for 2 h, $200mg/m^2$ CF and 1.0 g tegafur during d1~5. Whereas, control Group B received chemotherapy regimens which were same as Group A, but no addition of endostar. Before chemotherapy, patients were given intravenous injection of 8 mg ondansetron, intramuscular injection of 10 mg metoclopramide and 20 mg diphenhydramine for prevention of vomiting, protection of liver and stomach as well as symptomatic supportive treatment. One cycle was 21 d, 4~6 cycles in total. The efficacy was evaluated every 2 cycles. Results: 32 patients in Group A could be evaluated, and the response rate (RR) and disease control rate (DCR) were 59.38% and 78.13%, respectively. 31 patients in Groups could be evaluated, and the RR and DCR were 32.26% and 54.84%, respectively. The differences between 2 groups were significant. The toxic effects include myelosuppression, gastrointestinal reaction, fatigue, cardiotoxicity and peripheral neurotoxicity. Conclusions: Preliminary observations show that endostar (once every other day) combined with chemotherapy is effective in the treatment of advanced gastrointestinal cancer, with low toxic effects, good tolerance, deserving further study.

• Journal of Power System Engineering
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• v.21 no.5
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• pp.35-40
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• 2017

The effects of the different rib geometries such as V-shaped continuous (case A), parallel broken (case B), and V-shaped broken (case C) ribs on the heat transfer and pressure drops in a divergent channel with $45^{\circ}$ inclined ribs on one wall or two walls are checked out. The top and bottom walls are adiabatic; two side walls are uniformly heated in the divergent rectangular channel. The tested Reynolds numbers are ranged from 22,000 to 75,000. The channel with two opposite walls inclined only has the length of test section of 1 m and the channel divergence ratio of $D_{ho}/D_{hi}=1.49$, corresponding to $1.43^{\circ}$ inclined walls. The results show in the identical pumping power that the V-shaped continuous rib (case A) with two ribbed walls is the greatest, but the parallel broken rib (case B) with one ribbed wall is the worst in the thermal performance.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.3
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• pp.746-759
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• 2016

In this study, we monitored the status of marine environment of olive flounder, Paralichythys olivaceus, culture ground in Jeju-do, Republic of Korea. It reported the consumption of raw olive flounder meat containing of Kudoa, Kudoa septempunctata, could induce vomitting and diarrhea in Japan. The Kudoa is a new mycosporean species, researchers found Kudoa from the muscles of olive flounder cultured at western Japan and imported from Jeju-do. We choose two Kudoa positive farms and two negative farms in the mid of concern about the relation between Kudoa and habitat. We found two marine invasive species at the water-pumping seabed at one of the Kudoa positive farm. The concentration of pH and DO at on-growing flounder farms showed the decreasing pattern along side the raceway (influent sea waters > on growing sea waters > outfluent sea waters). The TN and TP values increased gradually following to the raceway (influent sea waters < on growing sea waters < outfluent sea waters). The concentration of COD and SS were in the range of $0.100-2.581mg{\cdot}L^{-1}$, $1.00-12.70mg{\cdot}L^{-1}$, respectively. The calculated residence time was 4hr 32minutes at F1, 11hr 21minutes at F2, and 9hr 50minutes at F3, respectively. It was calculated same distance of 4 km away from effluent pipes. Although direct relation between Kudoa and marine environment could not define well based on this study result, the more studies on marine environmental stressors for olive flounder are required to conduct as a reliable method including socio-economic group and environmental group.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.142-149
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• 2003

Blind hydraulic backfilling is a commonly used technique for subsidence control of the strata over unapproachable waterlogged underground excavations. In this investigation model studies on all the three variants of this technique, namely, hydro-pneumatic or air-assisted gravity backfilling, pumped-slurry backfilling and simple gravity backfilling, have been carried out in fully transparent models of the underground excavations. On examination of the filling process, it was revealed that in all the three cases, the basic process of filling occurs by sand transport along one or more meandering channels. The relative influence of sand, water and air flow rates on the area of filling from a single inlet point and the hydraulic pressure loss per unit length were studied in details. In hydro-pneumatic backfilling process, the air bubbles while moving upward through the meandering channels provide an additional buoyant force over and above the available hydraulic head. In this way the area of filling from a single borehole may be quite large even at small flow rates of water. During actual field implementation the injected air, if not released completely from the rise side holes, may cause troubles by way of creating potholes on the surface. The pumped-slurry technique has shown its capability of filling a relatively larger area at faster rate, especially when high-volume, low-pressure method was selected. But simple gravity filling was also found to be equally effective method as slurry pumping, especially when flow rates were high. In the second and third method discussed above, examination of variations of injection pressure was also done and its relation with physical phenomenon was also attempted. Some empirical relationships were also developed using multivariate regression with a view to help the practicing engineers.