• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.375-377
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• 2000

In this paper, voltage controlled APF(Active Power Filter) is introduced to improve power factor and reduce harmonic generated from nonlinear load. The voltage controlled APF which is consisted of inverter and passive filter operates with nonlinear load simultaneously. According to the results of simulation, it is proved that the proposed system has the performance of improving power factor and reducing harmonics.

• Journal of the Optical Society of Korea
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• v.6 no.2
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• pp.27-32
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• 2002

An integrated optical 2$\times$2 add/drop multiplexer in X-cut, Y-propagating LiNbO$_3$ has been demonstrated. The device consists of passive polarization splitters and acousto-optical mode converters with weighted coupling utilizing tapered acoustical directional couplers; their specific design and properties are discussed. The insertion loss has been measured to be about -8.16 ㏈ and -8.6 ㏈ for TE and TM polarizations, respectively. The device shows a 3 ㏈ bandwidth of 2.3 nm, a tuning rate 8.34 nm/MHz around λ = 1554 nm, and a sidelobe suppression of about 14.5 ㏈. Optimum operation is achieved with a RF drive power of about 43 ㎽. Multi-wavelength operation has been demonstrated.

• Child Health Nursing Research
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• v.29 no.3
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• pp.195-206
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• 2023

Purpose: This study aimed to investigate the perceptions of precocious puberty and elucidate the distinct characteristics of each type of perception related to precocious puberty among school-aged children who had undergone treatment for the condition. Methods: This study applied the Q methodology to identify and classify the perceptions of precocious puberty among school-aged children who had undergone treatment for the condition. The analysis involved 34 questions from the Q sample and data from 35 individuals in the P sample, using the PC-QUANL Program for analysis. Results: The perceptions of precocious puberty among school-aged children who had undergone precocious puberty treatment were classified into the following four types: "shyness - passive self-management," "resentment - suppression," "anxiety - fear," and "adaptation - acceptance." Conclusion: This study investigated the experiences and perceptions of children who have undergone treatment for precocious puberty. Through the identification of four types of perceptions, we can see that there is a need to develop an intervention program for nursing that is tailored to the specific type of precocious puberty.

• Journal of Radiation Protection and Research
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• v.37 no.3
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• pp.123-128
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• 2012

Evidence suggests that even low-dose irradiation can lead to progressive cognitive decline and memory deficits, which implicates, in part, hippocampal dysfunction in both humans and experimental animals. This study examined whether diethyldithiocarbamate (DDC) could attenuate memory impairment, using passive avoidance and object recognition test, and suppression of hippocampal neurogenesis, using the TUNEL assay and immunohistochemical detection with markers of neurogenesis (Kiel 67 (Ki-67) and doublecortin (DCX)) in adult mice treated with gamma radiation (0.5 or 2 Gy). DDC was administered intraperitonially at a dosage of 1,000 $mg{\cdot}kg^{-1}$ of body weight at 30 min. before irradiation. In passive avoidance and object recognition memory test, the mice, trained for 1 day after acute irradiation (2 Gy) showed significant memory deficits compared with the sham controls. The number of TUNEL-positive apoptotic nuclei in the dentate gyrus (DG) was increased 12 h after irradiation. In addition, the number of Ki-67- and DCX-positive cells were significantly decreased. DDC treatment prior to irradiation attenuated the memory defect, and blocked the apoptotic death. DDC may attenuate memory defect in a relatively low-dose exposure of radiation in adult mice, possibly by inhibiting a detrimental effect of irradiation on hippocampal neurogenesis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.557-563
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• 2007

Rain-wind induced cable vibration can cause serious problems in cable-stayed bridge. External dampers attached to the cables have become widely accepted as an effective means for stay-cable vibration suppression. For very long stay-cables, however, such damper systems are rendered ineffective, as the dampers need be attached near the end of cables for aesthetic reasons. A recent study by the authors proposed that a movable anchorage system is replaced direct fixed support of the cable with a support through a bearing and damper. This paper extends the previous work by adding active control system to mitigate the cable vibration. The response of a cable with the proposed active control system is obtained and then compared to those of the cable with and without an external passive damper. The results show that the active control system can provide superior protection than the passive control system for a cable vibration.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.17-23
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• 2008

We have investigated the properties of the novel rectangular ring lasers containing active and passive regions in a InP material system. The rectangular ring laser consists of four low loss total internal reflection mirrors and a directional coupler made out of passive three waveguide. Two different lasers haying active lengths of 250 and $350{\mu}m$ and total cavity lengths of 580 and $780{\mu}m$ are fabricated, respectively. For both devices lasing thresholds of 38 mA is obtained at room temperature and under continuous wave operation. Lasing is predominantly single mode with the side mode suppression ratio better than 20 dB.

• Wind and Structures
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• v.23 no.2
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• pp.127-142
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• 2016

Aerodynamic effects, such as drag force and flow-induced vibration (FIV), on civil engineering structures can be minimized by optimally modifying the structure shape. This work investigates the turbulent wake of a square prism with its faces modified into a sinusoidal wave along the spanwise direction using three-dimensional large eddy simulation (LES) and particle image velocimetry (PIV) techniques at Reynolds number $Re_{Dm}$ = 16,500-22,000, based on the nominal width ($D_m$) of the prism and free-stream velocity ($U_{\infty}$). Two arrangements are considered: (i) the top and bottom faces of the prism are shaped into the sinusoidal waves (termed as WSP-A), and (ii) the front and rear faces are modified into the sinusoidal waves (WSP-B). The sinusoidal waves have a wavelength of $6D_m$ and an amplitude of $0.15D_m$. It has been found that the wavy faces lead to more three-dimensional free shear layers in the near wake than the flat faces (smooth square prism). As a result, the roll-up of shear layers is postponed. Furthermore, the near-wake vortical structures exhibit dominant periodic variations along the spanwise direction; the minimum (i.e., saddle) and maximum (i.e., node) cross-sections of the modified prisms have narrow and wide wakes, respectively. The wake recirculation bubble of the modified prism is wider and longer, compared with its smooth counterpart, thus resulting in a significant drag reduction and fluctuating lift suppression (up to 8.7% and 78.2%, respectively, for the case of WSP-A). Multiple dominant frequencies of vortex shedding, which are distinct from that of the smooth prism, are detected in the near wake of the wavy prisms. The present study may shed light on the understanding of the underlying physical mechanisms of FIV control, in terms of passive modification of the bluff-body shape.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.7
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• pp.720-728
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• 2011

In this paper, development of the monopulse secondary surveillance radar antenna which can be used for IFF system is presented. This antenna that is passive linear array is comprised of the row-feeder and several array-elements. The row-feeder provides sum, different and SLS(Sidelobe Supression) channels which are optimized the distribution of the power and phase ratio. The azimuthe sidelobe level of the sum channel beam pattern is -20 dBc or less. The SLS channel covers the sidelobe of the sum-chanel in the whole azimuth angle range. And the difference channel is used to perform the mono-pulse function, improves the detection accuracy in the azimuth direction. Meanwhile, the arrayelement makes shaped beam in the elevation angle, in order to eliminate the clutter and multipath effects from the ground. Performance of the antenna developed is verified by the measurement of S-parameters and far-field beam pattern, and satisfies all of the development specifications well.

• Journal of Ginseng Research
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• v.33 no.2
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• pp.132-138
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• 2009

Previous studies suggest that even low-dose irradiation can lead to progressive cognitive decline and memory deficits, which implicates, in part, hippocampal dysfunction in both humans and experimental animals. In this study, whether red ginseng (RG) could attenuate memory impairment was investigated through a passive-avoidance and object recognition memory test, as well as the suppression of hippocampal neurogenesis, using the TUNEL assay and immunohistochemical detection with markers of neurogenesis (Ki-67 and doublecortin (DCX)) in adult mice treated with a relatively low-dose exposure to gamma radiation (0.5 or 2.0 Gy). RG was administered intraperitonially at a dosage of 50 mg/kg of body weight, at 36 and 12 h pre-irradiation and at 30 minutes post-irradiation, or orally at a dosage of 250 mg! kg of body weight/day for seven days before autopsy. In the passive-avoidance and object recognition memory test, the mice that were trained for one day after acute irradiation (2 Gy) showed significant memory deficits compared with the sham controls. The number of TUNEL-positive apoptotic nuclei in the dentate gyrus (DG) was increased 12 h after irradiation. In addition, the number of Ki-67- and DCX-positive cells was significantly decreased. RG treatment prior to irradiation attenuated the memory defect and blocked apoptotic death as well as a decrease in the Ki-67- and DCX-positive cells. RG may attenuate memory defect in a relatively low-dose exposure to radiation in adult mice, possibly by inhibiting the detrimental effect of irradiation on hippocampal neurogenesis.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.11 no.1
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• pp.40-53
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• 1998

Mast cells play an important role in the pathophysiologlcal changes observed in acute cutaneous and inflammatory diseases In order to see whether Kum-Hwang-San has an influence on mast cell- mediated immediate cutaneous reactions, the author has undertaken an animal study. Ears of mice were treated with a compound 48/80 solution topically at 30 min after the cutaneous application of Kum-Hwang-San. At each point, an ear swelling response was measured with a digimatic thickness micrometer. Ear swelling response induced by compound 48/80 was significantly suppressed dose-dependently by Kum-Hwang-San 30 min before topical application as compared with that in nonapplicated control mice, and the value returned to normal levels by 120 min. Compound 48/80- induced mast cell degranulation by Kum-Hwang-San was also remarkably decreased in accordance with the suppression in ear swelling response. Kum-Hwang-San dose-dependently inhibited histamine release from the rat peritoneal mast cells activated by compound 48/80. Another way to test acute cutaneous reaction is to induce passive cutaneous anaphylactic reaction. Kum-Hwang-San significantly inhibited passive cutaneous anaphylactic reaction activated by anti-dinitrophenyl IgE on both topical application and intradermal injection. Kum-Hwang-San also inhibited histamine release from the rat peritoneal mast cells induced by anti-DNP IgE. This study provides evidence that Kum-Hwang-San will be beneficial in the treatment of acute cutaneous diseases.