• Journal of IKEEE
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• v.26 no.1
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• pp.77-82
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• 2022

The effect of the bias network on the performance of the W-band power amplifier(PA) was investigated. The performances of the typical RC and radial stub networks were examined, and a hybrid network was proposed for W-band application and its performance was confirmed. To verify this, a W-band PA was designed using a 60-nm GaN pHEMT process. When hybrid networks were applied, the PA had improved stability in all frequency bands, secured about 9 dB of power gain at operating frequencies 87 GHz to 93 GHz, and the maximum PAE was found to be about 12.3% at output power of 26.7 dBm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.6
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• pp.719-725
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• 2019

We propose a 2.4-GHz CMOS power amplifier (PA) with a bypass structure to improve the power-added efficiency (PAE) in the low-power region. The primary winding of the output transformer is split into two parts. One of the primary windings is connected to the output of the power stage for high-power mode. The other primary winding is connected to the output of the driver stage for low-power mode. Operation of the high power mode is similar to conventional PAs. On the other hand, the output power of the driver stage becomes the output power of the overall PA in the low power mode. Owing to a turning-off of the power stage, the power consumption is decreased in low-power mode. We designed the CMOS PA using a 180-nm RFCMOS process. The measured maximum output power is 27.78 dBm with a PAE of 20.5%. At a measured output power of 16 dBm, the PAE is improved from 2.5% to 12.7%.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.99-102
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• 2008

In terms of operation profiles and building characteristics, Schools, as public facilities, are one of the most suitable buildings for small scale Renewable energy systems since they have its energy demand on daytime mostly and large open area, roof surface available for the installation of Renewable energy systems such as solar collectors or Photovoltaic pannels. This paper presents a methodology of the feasibility test for Renewable energy systems to be intalled at schools. The methodology is based on the analysis of the demand/supply profiles dynamic matching. a case study is also presented to test the applicability of the proposed assessment methodology.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.270-278
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• 2013

This paper proposes a control method for high voltage direct current(HVDC) with modular multilevel converter (MMC) under unbalanced voltage conditions considering the submodule(SM)'s current capacity and circulating current. It is aimed to propose a control method in which the current peak value does not exceed the maximum value of HVDC-MMC by considering the current capacity of the SM under unbalance voltage conditions. And it analyzes the effect of the unbalanced voltage on circulating currents in MMC and then proposes a control method considering each component of circulating currents under unbalanced voltages. The effectiveness of the proposed controlling method is verified through simulation results using PSCAD/EMTDC.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.91-96
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• 2005

In this paper, describes the design and performance of a 1.5 kW solid-state pulsed power amplifier, operating over 2.7-2.9 GHz at a duty of 10% and with a pulse width of 100 us for radar application. The solid-state pulsed power amplifier configures a series of 8-stage cascaded power amplifier with different RF output power levels. Low loss Wilkinson combiners are used to combine output powers of six 300W high power solid state modules. Tests show peak output power of 1.61 kW, corresponding to PAE of 26.2% over 2.7-2.9 GHz with pulse width of 100 us and a PRF of 1 kHz.

• The Plant Pathology Journal
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• v.20 no.4
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• pp.277-282
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• 2004

Amendments of a recirculating nutrient solution with potassium silicate were evaluated as a means to control Phytophthora capsici infections on pepper plant(Capsicum annuum L.). Supplying the solutions with 100 or 200 ppm of silicate significantly reduced motility, root decay, and yield losses attributed to infection of P. capsici. Treating inoculated plants with potassium silicate increased root dry weights and number of fruit, especially high-grade fruit. Results were slightly superior to non-inoculated controls. The two varieties, PBC 137 and PBC 602, responded similarly to the treatments. No significant differences were observed between the 100- and 200 ppm silicate treatments. Results were better when greenhouse conditions favored the spread of P. capsici. Silicon alone did not increase pepper yield, suggesting that it acts as a disease suppression agent rather than as a fertilizer, The phenomena by which silicon confers protection against P. capsici infection and disease development are not fully understood, but our results indicate that mechanisms other than a mechanical barrier to fungal penetration are involved.

• The Journal of Internal Korean Medicine
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• v.12 no.2
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• pp.129-137
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• 1991

This study has been carried out to investigate the cause symptom and treatment of wind-coughing ( 風嗽 ) by referring to 38 literatures. The results were obtained as follows; 1. The factors causing wind-coughing ( 風嗽 ) is wind-air. The 1st factors are mistaking of transport lung-air ( 肺氣不宣 ) and cleaning lung (肺失淸肅). 2. The symptom of wind-coughing ( 風嗽 ) is as follows. Bi Saek Sung Jung ( 鼻塞聲重 ), Gu Gun Hu Yang ( 口乾喉痒 ), A Mi Kung I Hae ( 語未竟而咳 ), Maek Bu ( 脈浮 ), Jeang Han Jang Yul ( 憎寒壯熱 ), Ja Han OU Pung ( 自汗惡風 ), Bun Jo ( 煩躁 ), Bi Ryu Chung Chae ( 鼻流淸?), Ya Jung 11 Jyung ( 夜重日輕 ). 3. The treatment-method of wind-coughing ( 風嗽 ) is as follow. Bal San Bul Ga Ha ( 發散 不可下 ), So Pung San Han ( 疏風散寒 ), Chung Yul ( 淸熱 ), Sun Pae Ji Hae ( 宣肺止咳 ). 4. The treatment-herbs of wind-coughing ( 風嗽 ) is as follow. Kwan Dong Hwa San ( 款冬花散 ), Gun Bi Cho San ( 金沸草散 ), Sam Yo Tang ( 三拗湯 ), Ji Hae San ( 止嗽散 ), Hang So San ( 杏蘇散), Sang Kuk Yeam ( 桑菊飮).

• Journal of the Korean Society of Costume
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• v.55 no.5 s.95
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• pp.87-100
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• 2005

This study was to provide the fundamental data for a scientific and rational clothing construction by investigating the length variation of the upper body surface, using the method of surgical tape. The subjects were 15 early elementary schoolgirls in Busan area classified by three somatotypes, Arm-movements were consisted of 6 types. The statistical analyses used in this study were mean, standard deviation and the ANOVA and LSD procedure. The results of the analysis of the length of the upper body surface are as follows: By arm-movements, in the items of horizontal, front neck base girth, back upper bust girth, back bust girth and back under bust girth were increased and the other standard lines were apt to be decreased. In the items of vertical, all standard lines of front side and side seam length showed increased, the lines of bark side were apt to be decreased. The shoulder length represented the maximum rate of decrease($-36.59\%{\~}-48.98\%$) in M6($180^{\circ}$) and the side seam showed the maximum rate of increase($49.74\%{\~}59.22\%$) in the same movement.

• Herbal Formula Science
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• v.10 no.2
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• pp.189-197
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• 2002

The inhibitory effects of ethanol extract of Radex Angelica uchiyamana, on LPS- or IFN- plus LPS-induced production of NO, and $TNF-{\alpha}$, and expression of iNOS and COX-2 were investigated in the activated RAW 264.7 cells. This extract significantly inhibited the production of NO and $TNF-{\alpha}$, and suppressed the expression of iNOS and COX-2 in a dose-dependent manner. These results show that ethanol extract of Radex Angelica uchiyamana may explain some known biological activities including anti-inflammatory effect, and is of considerable benefit in the treatment for NO and pro-inflammatory cytokine overproduction related immunological diseases.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.813-818
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• 2008

In order to reduce energy consumption, this study presents a way to energy reduction through energy-feedback which enables a household to self-recognize the need for energy reduction and respond to. The effect of this energy-feedback has been reported as $10{\sim}15%$ in average, and been actively investigated in abroad from 1970's while study in korea has been in its first step. In this study, examination on the cases of abroad study is made as it shows the effectiveness and applicability of energy feedback. And paradigms to consider for application to korea will be suggested anticipating the change of actions through energy feedback.