• 폴리머
• /
• 제34권4호
• /
• pp.306-312
• /
• 2010

Triphenylvinylsilane (TPVS) containing vinyl acetate (VAc), butyl acrylate (BA), and Nmethylolacrylamide (NMA) copolymers were prepared by emulsion polymerization. The polymerization was performed at $80^{\circ}C$ in the presence of auxiliary agents and ammonium peroxodisulfate (APS) as the initiator. Sodium dodecyl sulphate (SDS) and Arkupal N-300 were used as anionic and nonionic emulsifiers, respectively. The resulting copolymers were characterized by using Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and dynamic light scattering (DLS). Thermal properties of the copolymers were studied by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology of copolymers was also investigated by scanning electron microscopy (SEM) and then the effects of silicone concentrations on the properties of the TPVS-containing VAc-acrylic emulsion copolymers were discussed. The obtained copolymers have high solid content (50%) and can be used in weather resistant emulsion paints as a binder.

• 대한방사선치료학회지
• /
• 제18권2호
• /
• pp.89-96
• /
• 2006

목 적: 방사선치료를 목적으로 촬영된 CT영상을 이용하여 조직내 불균질 물질 및 체위고정 기구에 대한 보정이 선량계산 결과에 미치는 영향을 알아보고자 한다. 대상 빛 방법: 체내불균질 물질의 다양한 사례를 알아보기 위하여 본원에서 제작한 물팬텀($250{\times}250{\times}250mm^3$) 내부에 (1) 뼈 (2) 금속 (3) 조영제 (4) 고정기구(Head holder/Vac-lok) 등 CT Number를 변화시킬 수 있는 물질을 삽입하여 CT촬영을 시행 하였다. 각기 다른 형태의 불균질 CT영상을 전산화치료계획장치(RTP)에 입력하여 동일한 조건(SAD=100 cm 조사야=$10{\times}10cm^2$, 깊이=10cm, 1문조사)으로 에너지별(4, 6, 10 MV X-선) 처방선량 100 cGy를 얻기 위한 선량계산(MU)을 시행하여 비교, 분석하였다. 결 과: 물로만 구성된 팬텀을 기준값으로, 불균질 보정계수 차이는 뼈조직 상태인 경우는 $2.7{\sim}5.3%$, 금속물질인 경우 $2.7{\sim}3.8%$, 조영제인 경우 $0.9{\sim}2.3%$, Head holder $0.9{\sim}2.3%$, Head holder와 Pillow인 경우 $3.5{\sim}6.9%$, 그리고 Vac-lok인 경우 $0.9{\sim}1.5%$의 차이로 나타났다. 결 론: 체내의 불균질 보정계수 차이는 임상적으로 그 적용 형태가 다양하고, 일관성을 보이지 않으며, 조사문수가 증가함에 따라 그 차이가 1%미만으로 허용 가능할 것이나, 고정 기구등에 의한 불균질 보정은 충분히 고려하여 선량계산의 부정확도를 최소화 시켜야 할 것으로 사료된다.

• 폴리머
• /
• 제34권6호
• /
• pp.491-494
• /
• 2010

무유화 에멀젼 공중합법을 이용하여 180~200 nm의 지름을 가지는 단분산성 폴리(스티렌/디비닐벤젠/비닐 아세테이트) [poly(ST-co-DVB-co-VAc)] 고분자 나노입자를 합성하였으며, 제조된 단분산성 고분자 나노입자의 표면을 비누화반응을 통하여 개질하여 단분산성 폴리(스티렌/디비닐벤젠/비닐알코올) [poly(ST-co-DVB-co-VA)] 나노입자를 제조하였다. 합성된 입자를 반응염료와 반응시켜 적색과 청색 단분산성 폴리(스티렌/디비닐벤젠/비닐알코올) 나노입자를 제조하였으며, 입자의 형태, 분산성 및 표면전하를 전자현미경, 시차열분석기, UV/Vis 흡광기 및 제타 전하 측정장치를 이용하여 규명하였다.

• 한국정밀공학회지
• /
• 제29권11호
• /
• pp.1214-1220
• /
• 2012

Vibration assisted cutting (VAC) is one of the promising methods for precision machining, which has been normally equipped with piezoelectric materials. In this paper, a feasibility of applying magnetostrictive materials to VAC as a cutting device instead of piezoelectric materials was studied. For this, the vibrational characteristics of a magnetostrictive material was investigated with respect to a coil design, a preload, and the effects of a biasing and an exciting magnetic fields. The output strain of a magnetostrictive material is restricted due to an increasing inductive impedance as the exciting frequency increases and the heat of coil, etc. Through the experimental results, it was found that the biasing and the exciting magnetic field affected the output performance significantly but not the preload. In conclusion, the magnetostrictive material could be used only in the low frequency range but not a good candidate for high frequency actuating application.

• 대한미생물학회지
• /
• 제35권5_6호
• /
• pp.363-363
• /
• 2000

• Journal of Trauma and Injury
• /
• 제27권2호
• /
• pp.29-32
• /
• 2014

Pelvic bone fracture with hemodynamic instability is fatal and the mortality rate can range up to 40%. Despite the big advances in the treatment of massive bleeding and hemorrhagic shock, the mortality associated with hemodynamically unstable pelvic bone fractures remains high. The gold standard of treatment for pelvic bone fracture with hemodynamic instability has not yet been determined and is an issue of main discussion among many doctors. Retroperitoneal packing is not yet wide spread in Korea, but is a good modality for managing of massive bleeding from pelvic bone fractures when an angiography suite or an expert surgeon is not available. A vacuum-assisted closure (VAC) system can also be applied with retroperitoneal packing in the manner of damage control surgery and open abdomen surgery. We present the case of a 51-year-old male who had a pelvic bone fracture with massive bleeding. We performed retroperitoneal gauze packing with a VAC system for the first time. The postoperative vital signs of patient were immediately stable, the massive bleeding was easily and quickly controlled, and the amount of transfusion of blood components was reduced.

• Journal of the Korean Data and Information Science Society
• /
• 제22권4호
• /
• pp.735-740
• /
• 2011

최근 전자기기의 소형화, 인텔리전트화, 다기능화, 광대역화에 관심이 집중되어 많은 발전이 이루어졌으며, 이들 전자기기들에 이용되는 모듈형의 전원장치 (SMPS : Switching-mode power supply)도 소형화, 경량화, 고효율화, 고신뢰성화, 저노이즈화를 실현하고 있다. 85~265 볼트교류전압(VAC : Voltage alternating current) 상용 전원을 공급받아 DC 출력을 공급하는 전원장치인 파워모듈은 마이크로컨트롤러, 릴레이 등 전기, 전자 회로용 전원 공급기를 간단하고 쉽게 설계하도록 개발되고 있다. 이 모듈은 전원을 사용하는 장비에 광범위하게 적용할 수 있어 에너지 절감이라는 세계적인 대과제에 적합한 제품이기는 하나 제품의 품질과 성능에 대한 통계적분석이 필요한 바 적용제품의 부하별, 출력전압별 성능분석을 하여 그 문제점을 찾아보려고 한다.

• Journal of Power Electronics
• /
• 제18권6호
• /
• pp.1642-1649
• /
• 2018

A single-stage flyback LED AC-DC converter based on primary-side control under constant current mode is proposed in this study. The proposed converter features low total harmonic distortion (THD) and high power factor (PF). It also consists of a zero-crossing distortion compensation circuit and a variable duty ratio control compensation circuit to deal with the line current distortions caused by fixed duty ratio control. The system model and layout are built in Simplis and Cadence, respectively. The feasibility and performance of the proposed circuit is verified by designing and fabricating an IC controller in the HHNEC $0.35{\mu}m$ 5 V/40 V HVCMOS process. Experimental results show that the PF can reach a level in the range of 0.985-0.9965. Moreover, the average THD of the entire system is approximately 10%, with the minimum being 6.305%, as the input line voltage changes from 85 VAC to 265 VAC.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 D
• /
• pp.1563-1565
• /
• 1999

Linear and nonliear complex permittivities have been measured for amorphous copolymers of vinylidene cyanide (VDCN) with vinyl acetate (VAc), vinyl propionate (VPr), vinyl benzoate (VBz), styrene (St) and methyl methacrylate (MMA). It is found that the third order permittivity ${\varepsilon}_3$ depends upon frequency according to a function ${\Delta}_{{\varepsilon}_3}/(1+i{\omega}{\tau}_^3)$ while the linear permittivity obeys a Debye function ${\Delta}_{{\varepsilon}_1}/(1+i{\omega}{\tau}_1)$. Experimental results are well fitted by the above predicted functions except at low frequencies where dc conduction dominates. The ${\tau}_1$ and ${\tau}_3$ are nearly equal, and depend upon temperature according to a WLF form. The relaxation strength ${\Delta}_{{\varepsilon}_1}$ depends upon comonomers ranging from $130_{{\varepsilon}_0}$(VAc) to $20{{\varepsilon}_0}$(MMA). The ${\Delta}_{{\varepsilon}_3}$ is negative and depends more strongly upon comonomers. Combined knowledge about linear and nonlinear permittivities predicts very large correlation factors which indicates strongly cooperative dipolar motions in those amorphous copolymers.

• Journal of Electrical Engineering and Technology
• /
• 제8권1호
• /
• pp.137-143
• /
• 2013

This paper presents development of variable speed generation (VSG) system with energy saving function. The rubber tyred gantry crane (RTGC) requires the power from diesel-engine. Significant fuel savings by reducing the engine speed can be achieved, because all of operation modes except hoisting are required lower power than rated value of engine. When low speed operation output voltage of generator is decrease until acceptable range of motor driver inverters and auxiliary load supplier. According to power demand engine speed is varying from 20 to 60Hz, and voltage is varying between 210Vac and 480Vac. When idle mode or low power operation dc/dc converter operates by constant output voltage control and inverters dc site voltage is compensated by it. This paper proposed 3-phase interleaved boost converter which has the same structure as the commercially available 3-phase inverter and current sharing capability. 400kW interleaved converter is designed and a performance of converter is evaluated through several experiments with a RTGC system. Energy saving VSG system can cut down fuel consumption by 36% and 21.3% at idle and unidirectional load operations.