• Childhood Kidney Diseases
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• v.15 no.1
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• pp.58-65
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• 2011

Purpose: Some hormonal and electrolyte abnormalities have been reported in pediatric patients with urinary tract infection (UTI). This study aimed to investigate the relationships between the imbalance of electrolytes and the severity of infection and associated urologic anomalies in children with febrile UTI. Methods: We retrospectively reviewed 267 patients with febrile UTI who were admitted to Korea University Guro Hospital during the period from January, 2007 until February, 2010. According to the presence of hyponatremia or hyperkalemia, clinical parameters and associated renal anomalies, such as hydronephrosis, cortical defects and vesicoureteral reflux, were compared. Results: 42.7% of all patients had decreased concentration of serum sodium. In patients with decreased concentration of serum sodium, cortical defects were significantly increased compared to normal patients (40.4% vs. 14.4%, P <0.05). White blood cell (WBC) counts ($15,721{\pm}6,553/uL$ vs. $12,885{\pm}5,367/uL$, P <0.05), C-reactive protein (CRP) ($61.8{\pm}56.1$ mg/L, vs. $29.9{\pm}39.8$ mg/L, P <0.05), and erythrocyte sedimentation rate (ESR) ($43.9{\pm}34.3$ mm/hr vs. $27.4{\pm}26.8$ mm/hr, P <0.05) in peripheral blood showed significant increases in the group with decreased concentration of serum sodium. Duration of fever, presence of gastrointestinal symptom, the incidence of hydronephrosis and vesicoureteral reflux did not differ between the two groups. None of the patients had significant hyperkalemia. Conclusion : We suggest that decreased concentration of serum sodium in febrile UTI might be a helpful marker for leukocytosis and increased CRP and ESR in peripheral blood, and acute pyelonephritis.

• The Journal of Dong Guk Oriental Medicine
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• v.6 no.1
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• pp.177-203
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• 1997

Various kinds of medicinal herbs and prescribed herb medicines which have usually been used for treatment of reducing fever, purging intense heat, and detoxication were secreened for antibacterial activity against Proteus vulgaris, S. aureus, and E. faecalis which causing puerperal infection. Minimal inhibitory concentrations of water and ethanol-soluble extracts of Hwangyon(C. japonica), Omae(P. mume), and Omiza(S. chinensis) were determined and using thin-layer chromatography the extracts of Hwangyon and Omiza were separated. The results obtained were as follow : 1. The water-soluble extracts of Keumeunhwa(L. japonica), Chiza(G. jasminoides), Hwangyon(C. japonica), Dansam(S. miltiorrhiza), Omae(P. mume) and Omiza(S. chinensis) showed antibacterial activities against P. vulgaris ; among them, the extracts of Hwangyon, Omae, and Omiza showed high antibacterial activities. The water-soluble extracts of Keumeunhwa(L. japonica), Hwangyon(C. japonica), Hwangkeum(S. baicalensis), Hwangbaek(P. amurense), Dansam(S. miltiorrhiza), Daehwang(R. coreanum), Omae(P. mume), Omiza(S. chinensis), Gingseng(P. ginseng), and Gamcho(G. uralensis) showed antibacterial activities against S. aureus : among them, the extracts of Hwangyon and Omiza showed high antibacterial activities. The water-soluble extracts of Banggi(C. trilobus), Daehwang(R. coreanum), Omae(P. mume), Omiza(S. chinensis), and Gamcho(G. uralensis) inhibited the cell growth of E. faecalis : among them, Omae and Omiza showed high antibacterial activities. The extract of Hwangyon(C. Japonica) and Omae(P. mume) showed no inhibition against E. coli. However, the extract of Omiza(S. chinensis) inhibited cell growth of both E. coli and B. subtilis. 2. The water- and ethanol-soluble extract of Hwangyon(C. Japonica) showed antibacterial activities against P. vulgaris and S. aureus, those of Omae(P. mume) against P. vulgaris and E. faecalis, and those of Omiza(S. chinensis) against all species tested, P. vulgaris, S. aureus, and E. faecalis. With the exception that ethanol-soluble extract of Hwangyon(C. japonica) showed much higher antibacterial activity against S. aureus than water-soluble one, antibacterial activities of both water-and ethanol-soluble ones were similar to each other of other two medicinal herbs. 3. When the prescribed herb medicines were tested, Sambohwan showed antibacterial activities against P. vulgaris and S. aureus. No prescribed herb medicine inhibitied the cell growth of E. faecalis. 4. Minimal inhibitory concentrations(MICs) of both water- and ethanol-soluble extracts of Hwangyon(C. japonica), Omae(P. mume), and Omiza(S. chinensis) against P. vulgaris were $2.5mg/m{\ell}$, $10mm{\ell}$, and $20mg/m{\ell}$, respectively. Those of both Hwangyon(C. japonica) and Omiza(S. chinensis) against S. aureus were $1.25mg/m{\ell}$ and $10mg/m{\ell}$, respectively. MICs of water-soluble extracts of Omae(P. mume) and Omiza(S. chinensis) against E. faecalis were $2.5m{\ell}$ and $5m{\ell}$, and those of ethanol-soluble extracts were $5m{\ell}$ and $10m{\ell}$, respectively Except for those of E. faecalis the cell growth of P. vulgaris and S. aureus were inhibited by much lower concentration of ethanol-soluble extracts used. As a result, the antibacterial compounds against P. vulgaris S. aureus, and E. aecalis are contained in the extracts of Hwangyon(C. japonica), Omae(P. mume), Omiza(S. chinensis), the prescribed herb medicine, Sambohwan, and might be used for treatment of puerperal infection. Further study should be carried out to identify which compounds affect the cell growth inhibition of P. vulgaris S. aureus, and E. faecalis.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.447-453
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• 2006

This paper proposes that 5 phase step motor drive system has high performance utilizing a micro step control with a current controller. Also this paper proposes an analog current controller to minimize size of the 5 phase step motor drive system. It has better advantages of cost and noise and heating than commercial products. As a result, Applying this system to position control robot the validity of suggested analog current controller and driver system is verified.

• Tribology and Lubricants
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• v.6 no.2
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• pp.60-67
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• 1990

최근 전자 및 광학 분야에 있어서의 눈부신 발전은 다면경 가공기나 초정밀 연삭기와 같은 초정밀 가공기계의 개발과 실용화에 힘입은 바 크다. 이러한 초정밀 가공기의 성능을 좌우하는 핵심 요소로서 추축계를 들수 있으며, 비교적 소형 경량의 공박물을 가공하는 기계의 주축용 베어링으로는 오일 베어링을 대신하여 공기 베어링이 점차 널리 사용되고 있다. 이러한 가공기에 많이 사용되는 외부 가압 공기 베어링은 동압 공기 베어링과는 달리, 외부에서 가압된 압축공기에 의하여 공기막을 형성하므로, 시동과 정지시 마멸이 없고 저속에서도 비교적 높은 하중 지지력을 얻을 수 있으며, 오일 베어링과 비교하여서는 발열이 적고 윤활제의 유출에 의한 오염의 위험이 없다는 특성외에 공기막에 의한 평균화 효과에 의하여 고정도의 운전이 가능하다는 장점이 있다. 본 연구에서는 점급기원의 가정하게 직접 수치해법을 사용하는 해석 프로그램을 작성하여, 무차원화된 설계 변수들에 대한 외부가압 공기베어링의 정$\cdot$동특성수들을 구하고자 한다.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.152-154
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• 2006

많은 자동화기기를 사용하는 산업현장에서 모터로부터의 하모닉 발생은 필연적이다. 또한 초정밀 고속제어를 함에 있어서는 더욱더 많은 하모닉이 발생하게 된다. 이러한 하모닉은 내부 코일에 발열을 증가시키며 정상상태 전류정격을 감소시키고 부품의 열화로 제품의 수명을 감소시킨다. 본 논문에서는 고강성 제어기를 사용함으로써 나타나는 하모닉을 주파수 분석을 통하여 연구하였다. 주파수 영역을 분석하는 방법으로 하드웨어 계산능력을 고려하여 FFT기법을 적용하였으며 시스템에 따라 하모닉의 크기와 주파수가 달라지므로 시스템에 따라 적절히 주파수 대역을 바꿀 수 있는 프로그램을 개발하였다. 본 연구실에서 Simulink 모델로 이미 개발되어 있는 고강성 제어기에 대하여 개발된 프로그램을 적용함으로써 고강성 제어기의 하모닉 특성을 Simulink로 분석하였다.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1264-1266
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• 2000

본 논문에서 비교하는 두 시스템은 모두 전력계통에서 발생할 수 있는 고조파 전류를 효과적으로 보상할 수 있는 시스템이다. 전력계통에서 고조파전류는 계통전압에 장해를 주기 때문에, 프릿카나 각종 전력용기기의 발열 진동, 소음 혹은 유도잡음 장해등의 원인이 된다. 따라서, 이에 대한 대책이 중요한 문제가 되고 있다. 본 논문은 이러한 고조파보상 시스템의 새로운 형태로써, 플라이휠에 의해서 만들어지는 에너지 저장시스템에, 전압형 PWM 인버터를 병용하여 순시제어가 가능한 시스템을 설계하는 것이다. 그리고 여기에 사용되는 회전기로 각각 권선형과 농형을 사용하여 시스템을 구성하고 그 특징과 장/단점을 비교 분석하였다.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1015-1020
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• 2012

Lignite of low rank coal and petroleum coke of high sulfur content can be high potential energy sources for coal gasification process because of their plentiful supply. The steam gasification of lignite, anthracite, and pet coke has been carried out in both an atmospheric thermobalance reactor and a lab-scale fludized bed reactor (0.02 m i.d. ${\times}$ 0.6 m height). The effects of gasification temperature ($600{\sim}900^{\circ}C$) and partial pressure of steam (0.15~0.95 atm) on the gasification rate and on the heating value of product gas have been investigated. The modified volumetric reaction model was applied to the experimental data to describe the behavior of carbon conversion, and to evaluate kinetic parameters of char gasification. The results shows that higher temperature bring more hydrogen in the product syngas, and thus increased gas heating value. The feed rate of steam is needed to be optimized because an excess steam input would lower the gasification temperature which results in a degradation of fuel quality. The rank of calorific value of the product gas was anthracite > lignite > pet coke. Their obtained calorific value at $900^{\circ}C$ with 95% steam feed were 10.0 > 6.9 > 5.7 $MJ/m^3$. This study indicates that lignite and pet coke has a potential in fuel gas production.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.1
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• pp.19-29
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• 2003

This paper proposes a CMOS readout circuit for uncooled micro-bolometer arrays adopting a four-point step calibration technique. The proposed readout circuit employing an 11b analog-to-digital converter (ADC), a 7b digital-to-analog converter (DAC), and an automatic gain control circuit (AGC) extracts minute infrared (IR) signals from the large output signals of uncooled micro-bolometer arrays including DC bias currents, inter-pixel process variations, and self-heating effects. Die area and Power consumption of the ADC are minimized with merged-capacitor switching (MCS) technique adopted. The current mirror with high linearity is proposed at the output stage of the DAC to calibrate inter-pixel process variations and self-heating effects. The prototype is fabricated on a double-poly double-metal 1.2 um CMOS process and the measured power consumption is 110 ㎽ from a 4.5 V supply. The measured differential nonlinearity (DNL) and integrat nonlinearity (INL) of the 11b ADC show $\pm$0.9 LSB and $\pm$1.8 LSB, while the DNL and INL of the 7b DAC show $\pm$0.1 LSB and $\pm$0.1 LSB.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.161-164
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• 2004

변압기는 권선방법에 따라 많은 특성의 변화를 나타내게 되는데 일반적인 동선의 권선법과 코일형태로 동판을 가공하여 사용하는 평면 권선방법, 그리고 고전류용 변압기에 이용되는 것으로 코어의 권선창 표면을 감싸는 형태의 관형 권선방법의 3가지의 코일 형태 또는 권선방법에 따른 변압기의 특성 변화와 컨버터에 채용되었을 때의 전력효율에 대하여 고찰하였다. 평면 코일을 이용한 변압기는 높은 코일간의 결합도로 인해 가장 낮은 누설인덕턴스와 가장 높은 성능지수 및 결합계수를 나타내었고, 관형코일을 이용한 변압기는 높은 누설특성으로 인해 가장 낮은 성능지수와 결합계수를 나타내었다. 그리고 이들을 DC-DC 컨버터에 채용하여 분석한 결과 평면변압기가 가장 높은 효율을 발휘하였다. 관형변압기는 저전력에서는 높은 누설량으로 인해 효율이 상대적으로 낮지만 출력전력이 증가할수록 상승하는 발열량에 대한 방열효과가 높아 효율의 감소폭이 작아서 고주파 또는 대전류용 변압기 응용이 기대된다.

• Pediatric Infection and Vaccine
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• v.6 no.2
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• pp.203-209
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• 1999

The beneficial effects of antibiotics in acute diarrhea of children were analysed 10 assess their effectiveness since many physicians use them to treat acute diarrhea. Searching 124 charts of patients admitted from August 1996 to July 1997, they were divided into two groups, an antibiotic negative (N) group of 28 patients and a positive (P) group of 96 patients. The admission period was significantly shorter in N group than P group (P=0.0057). Duration of fever and diarrhea were also shorter in N group (P=0.0328 and 0.0184 respectively). Although it was not statistically significant. duration of vomit and frequency of diarrheal episodes per day were lower in N group (P=0.7091 and 0.061, respectively). Age, sex, duration of diarrhea before the admission and CRP collected on the day of admission were not statistically different between the two groups (P=0.5866, 0.093, 0.3502 and 0.2628 respectively).