• Proceedings of the KSR Conference
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• 2003.10c
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• pp.493-499
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• 2003

Railroad, a superior mode of public transportation provides safe, efficient, speedy, comfortable and economical service, has fundamentally different characteristics from airplanes, ships and cars. Among the unique characteristics of a railroad is the fact that it operates on fixed track with multiple car trains. The subway system was first selected as the best solution to difficult automobile traffic conditions and environmental problems. Seoul subway no.1line (Jongno line) was opened for service on August 15, 1974. Seoul city has completed and now operates eight subway lines (286.7km) since 1974. At present the subways operate in Busan, Daegu and Incheon city, and are under construction in Gwangju and Daejeon city. The power source for subway trains has been electricity since 1896, and power supply systems are the third rail type and/or the catenary system. The typical catenary system is the rigid bar type. R-bar and T-bar are used in the rigid bar type of catenary system, and the two types of R-bar and T-bar are uesd in Korea also. R-bar is used only for AC 25kV power supply and T-bar for DC 1,500V. From 30 years of subway experience I would like to suggest the most economic catenary system to ensure of safety, reliability and expediency for the railway lines to be constructed and the forthcoming replacement due to the life cycle after studying and analysing the characteristics, advantages and disadvantages of R-bar and T-bar.

• Journal of Pharmaceutical Investigation
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• v.27 no.3
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• pp.207-212
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• 1997

The bioequivalence of two nabumetone tablets was evaluated in 16 normal male volunteers $(age\;21{\sim}30\;yrs)$ following oral administration. Test product was 'Nacton tablet' made by Jin Yang Pharmaceutical Co. and reference product was 'Unimeton tablet' made by Dong Kwang Pharmaceutical Co.. After one tablet containing 500 mg of nabumetone was administered, blood was taken at predetermined time intervals and the concentration of 6-methoxy-2-naphthylacetic acid, active metabolite of nabumetone, in plasma was determined with an HPLC method using fluorescence detector. AUC, $C_{max}$ and $T_{max}$ were calculated and statistically analyzed for the bioequivalence of the two products. The results showed that the differences in AUC, $C_{max}$ and $T_{max}$ between two products were 3.66%, 6.87% and 1.85%, respectively. The powers$(1-{\beta})$ for AUC, $C_{max}$ and $T_{max}$ were 91.4%, 88.9% and 81.1%, respectively. Detectable differences$({\Delta})$ and confidence intervals were all less than 20%. All of these parameters met the criteria of FDA for bioequivalence, indicating that "Nacton tablet" is bioequivalent to 'Unimeton tablet'.

• Korean Journal of Environmental Agriculture
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• v.42 no.2
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• pp.152-158
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• 2023

This study was conducted to evaluate the effects on soil chemical properties and plant growth after applying soldier fly compost (SFC). Treatments were as follows. No fertilizer (NF), control, SFC1 (SFC 250 kg/10a), SFC2 (SFC 500 kg/10a) and SFC3 (SFC 1,000 kg/10a). As compared to control in the pot test, organic matter (OM) and exchangeable sodium (Ex-Na) of SFC3 treatment were increased, and growth and nutrient uptake of young radish were not significantly different. Correlation coefficient between soil chemical factors like total nitrogen (T-N), OM, and CEC and uptake of nitrogen (N) and phosphorus (P) was significantly positive (p≤0.05). Compared to control in the field test, electrical conductivity, T-N, OM, Av.-P₂O₅, and CEC was increased, and lettuce growth was not significantly different. Correlation coefficient between application amount of SFC and T-N, OM, and Av.-P₂O₅ was significant positively (p≤0.05). These results indicated that the application of SFC improved nutrient availability of soil by increasing OM and CEC.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.31 no.2
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• pp.11-23
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• 2018

목적 : 본 연구에서는 $TNF-{\alpha}$와 $IFN-{\gamma}$로 자극한 인간피부각질형성세포 (HaCaT keratinocytes) 모델을 사용하여 지모가 피부장벽 기능에 미치는 영향을 알아보고자 하였다. 방법 : MTT assay를 통하여 지모 주정(70% 에탄올) 추출물 (EAA)이 HaCaT keratinocytes의 세포생존율에 미치는 영향을 확인하였으며 wound healing assay를 통해 EAA가 HaCaT 세포의 이주 능력에 영향을 주는지 관찰하였다. 또한 western blot analysis와 qRT-PCR을 통하여 EAA가 $TNF-{\alpha}/IFN-{\gamma}$로 자극한 HaCaT 세포에서 iNOS의 단백질 발현 및 IL-4, IL-13, IL-6의 mRNA 발현, filaggrin의 단백질과 mRNA 발현에 미치는 영향을 조사하였다. 결과 : EAA는 처리 농도 $500{\mu}g/ml$까지 HaCaT keratinocytes의 세포생존율에 영향을 미치지 않았다. EAA는 wound healing assay에서 HaCaT 세포의 이주 능력을 증가시켰으며, $TNF-{\alpha}/IFN-{\gamma}$로 자극한 HaCaT 세포에서 iNOS의 단백질 수준을 감소시켰다. 또한 EAA가 IL-4, IL-13, IL-6의 mRNA 발현을 억제하는 것 역시 확인할 수 있었다. 뿐만 아니라 EAA는 $TNF-{\alpha}/IFN-{\gamma}$ 자극에 의해 감소했던 filaggrin을 단백질과 mRNA 수준에서 회복시켰다. 결론 : EAA가 HaCaT 세포에서 Th2 type cytokines, pro-inflammatory cytokine의 억제와 filaggrin 회복을 통해 피부장벽 기능 손상에 대한 억제활성을 갖는 것을 확인하였으며, 이를 통해 EAA가 염증으로 인해 손상된 피부장벽 기능 개선에 효과적일 것으로 사료된다.

• Journal of Korean Medicine Rehabilitation
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• v.28 no.2
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• pp.61-72
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• 2018

Objectives The purpose of this experiment is to evaluate 4 weeks DRF (Dose Rate Finding) and single oral dose toxicity of ChondroT in rats. Methods In 4-week DRF, male and female Sprague-Dawely rats were treated with ChondroT at oral dose of 0, 500, 1000, and 2000 mg/kg. clinical signs, body weight, food consumption, necropsy findings, organ weight, hematological and blood-chemical parameters, and histological findings were monitored for 4 weeks. Also, after single oral administration of ChondroT, mortality, clinical signs, body weight, and necropsy findings were minitored for 2 weeks. Results In 4-week DRF and single dose oral toxicity study of ChondroT in sprague-Dawley rats, ChondroT did not exhibit any toxicity under the study conditions employed. Conclusions The results suggested a no-observed adverse effects level (NOAEL) was over 2,000 mg/kg/day in SD rats after oral administration, this study could be used as basic study of the repeated dose 13-week oral toxicity study of ChondroT.

• Korean Journal of Materials Research
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• v.32 no.5
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• pp.264-269
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• 2022

Ti₃C₂T_x MXene, which is a representative of the two-dimensional MXene family, is attracting considerable attention due to its remarkable physicochemical and mechanical properties. Despite its strengths, however, it is known to be vulnerable to oxidation. Many researchers have investigated the oxidation behaviors of the material, but most researches were conducted at high temperatures above 500 ℃ in an oxidation-retarding environment. In this research, we studied changes in the structural and electrical properties of Ti₃C₂T_x MXene induced by low-temperature heat treatments in ambient conditions. It was found that a number of TiO₂ particles were formed on the MXene surface when it was mildly heated to 200 ℃. Heating the material to higher temperatures, up to 400 ℃, the phase transformation of Ti₃C₂T_x MXene to TiO₂ was accelerated, resulting in a TiO₂/Ti₃C₂T_x hybrid. Consequently, the metallic nature of pure Ti₃C₂T_x MXene was transformed to semiconductive behavior upon heat-treating at ≥ 200 ℃. The results of this research clearly demonstrate that Ti₃C₂T_x MXene may be easily oxidized even at low temperatures once it is exposed to air.

• Progress in Medical Physics
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• v.12 no.2
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• pp.113-124
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• 2001

For veterinary imaging diagnosis, we obtained MR images of the canine brain, spine, kidney and pelvis from 3T MRI system which was equipped with the world first 3T active shield magnet. Spin echo (SE) and fast Spin Echo (FSE) images were obtained from the canine brain, spine, kidney and pelvis of normal and sick dogs using a homemade birdcage and transverse electromagnetic (TEM) resonators operating in quadrature and tuned to 128 MHz. In addition, we employed a homemade saddle shaped RF coil. Typical common acquisition parameters were as follows: matrix=512$\times$512, field of view (FOV)=20cm, slice thickness=3 w, number of excitations (NEX)=1. For T1-weighted MR images, we used TR=500 ms, TE=10 or 17.4 ms. For T2-weighted MR images, we used TR=4000 ms, TE=108 ms. Signal to noise ratio (SNR) of 3T system was measured 2.7 times greater than that of prevalent 1.57 system. The high resolution images acquired in this study represent more than a 4-fold increase in in-plane resolution relative to conventional images obtained with a 20 cm field of view and a 5 mm slice thickness. MR images obtained from 3T system revealed numerous small venous structures throughout the image plane and provided reasonable delineation between gray and white matter The present results demonstrate that the MR images from 3T system could provide better diagnostic quality of resolution and sensitivity than those of 1.5T system. The elevated SNR observed in the 3T high field magnetic resonance imaging can be utilized to acquire images with a level of resolution approaching the microscopic structural level under in vivo conditions. These images represent a significant advance in our ability to examine small anatomical features with noninvasive imaging methods. Moreover, MRI technique could begin to apply for veterinary medicine in Korea.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.165-170
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• 2001

AIC$_3$:$^{t}$ BuNH$_2$단일 전구체를 이용하여 MOCVD방법에 의해 상압하에서 1$\mu\textrm{m}$의 두께로 증착하였다. 증착된 AIN 박막을 XRD, SEM, RBS 그리고 AES로 분석했으며 IDT전극을 형성하기 위해 1500＋ 의 두께로 증착했다. 중심주파수 1.5GHz를 갖고 입출력 개수가 각각 500개이며 IDT선폭이 l$\mu\textrm{m}$인 전송형의 SAW filter를 제작하고자 하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.456-459
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• 2008

The 10t/d pyrolysis demonstration plant for waste tire recycling have been constructed and operated for commissioning of the plant. The plant have the tube reactor with chain conveyer attached disk. The reactor temperature is 500$\sim$600deg.C and pressure is -80$\sim$-100mmHg. Non-condensable gas is used as fuel for pyrolysis heat source.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.141-144
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• 2000

Recently DC-DC converters significantly increase the total losses as rising switching frequency. Traditional soft switching technique for reducing switching losses even increase voltage/current stress of switch. In this paper Resonant circuit for soft switching is connected in parallel with power stage and only operates just before turn-on of the main operates just before turn-on of the main switch, Therefore This doesn't affect the total circuit operation. ZNT-PWM converter designed with 170-260V input 4--V 5A output and 100kHz switching frequency is tested respectively with 500W. 1kW, 1.5kW, and 2kW loads.