• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.794-797
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• 2004

The object of investigation is represented by PbxSrl-xTiO3(PST) thin films, which were fabricated by the alkoxide-based sol-gel method on Pt/Ti/SiO2/Si substrate. We have investigated both structural and dielectric properties of PST thin films aimed to tunable microwave device applications as a function of Pb/Sr ratio. PST thin films showedtypical polycrystalline structure with a dense microstructure without secondary phase formation. Dielectric properties of PST films were found as strongly dependent on Pb/Sr composition ratio. Increasing of Pb content leads to simultaneous increasing of both dielectric constant and dielectric loss characteristics of PST films. The figure of merit (FOM) Parameter (FOM : (%) tunability / tan (%)) reached a maximal value of 27.5 corresponding to Pb/Sr ratio of 40/60. The tunability increased with increasing Pb content. The dielectric constants, dielectric loss and tunability of the PST thin films at Pb/sr ratio of 40/60 measured at 100 kHz were 335, 0.0174 and 47.89 %, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.809-812
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• 2004

(Pb,Sr)TiO3 (PST) thin films were fabricated by using the alkoxide-based sol-gel method. The PST stock solution was made and then spin-coated onto a PUTi/SiO2/Si substrate. The coating and drying procedures were repeated several times, and the PST thin films were sintered at 450-650 C for 1 h. All PST thin films showed dense and homogeneous structures without the presence of any rosette structure. The thicknesses of the PST thin films were approximately 200 nm. The dielectric constant and the dielectric loss of the PST thin films sintered at 550 C were about 404 and 0.0023, respectively. The leakage current density of the PST thin film sintered at 550 C was 3.13 x 10-8 A/cm2 at 1 V.

• IMMUNE NETWORK
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• 제23권6호
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• pp.47.1-47.16
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• 2023

Scrub typhus, a mite-borne infectious disease, is caused by Orientia tsutsugamushi. Despite many attempts to develop a protective strategy, an effective preventive vaccine has not been developed. The identification of appropriate Ags that cover diverse antigenic strains and provide long-lasting immunity is a fundamental challenge in the development of a scrub typhus vaccine. We investigated whether this limitation could be overcome by harnessing the nanoparticle-forming polysorbitol transporter (PST) for an O. tsutsugamushi vaccine strategy. Two target proteins, 56-kDa type-specific Ag (TSA56) and surface cell Ag A (ScaA) were used as vaccine candidates. PST formed stable nano-size complexes with TSA56 (TSA56-PST) and ScaA (ScaA-PST); neither exhibited cytotoxicity. The formation of Ag-specific IgG2a, IgG2b, and IgA in mice was enhanced by intranasal vaccination with TSA56-PST or ScaA-PST. The vaccines containing PST induced Ag-specific proliferation of CD8⁺ and CD4⁺ T cells. Furthermore, the vaccines containing PST improved the mouse survival against O. tsutsugamushi infection. Collectively, the present study indicated that PST could enhance both Ag-specific humoral immunity and T cell response, which are essential to effectively confer protective immunity against O. tsutsugamushi infection. These findings suggest that PST has potential for use in an intranasal vaccination strategy.

• 대한수의학회지
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• 제38권1호
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• pp.43-52
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• 1998

서방형 돼지성장호르몬(sustained-release formulation of porcine somatotropin, PST-SR)을 1주 간격으로 6차례 피하 및 근육주사하고 혈액과 조직중의 돼지 성장호르몬(PST)과 insulin-like growth factor 1(IGF-1)의 농도를 측정하여 다음과 같은 결과를 얻었다. 대조군의 혈중 PST와 IGF-1의 농도는 각각 2.41과 95.2 ng/ml 이었다. 1. PST-SR을 투여한 후 PST의 혈중농도는 8시간만에 최대에 도달하여(30 ng/ml) 곧 감소하였다. 혈중농도 반감기(decay half life)는 91~227시간이었다. IGF-1의 혈중농도는 투여후 12시간에 최대에 도달하였으며(165 ng/ml), 이후 서서히 감소되었고 반감기는 77~99시간이었다. 2. 혈중 PST농도-시간의 자료는 제재에서 PST가 유리되는 과정에는 두단계 즉, 투여후 24시간까지의 유리속도가 빠른 단계와 그 이후의 유리속도가 느린 단계가 있음을 보여주었다. 3. 여섯번의 반복투여기간에는 PST의 혈중농도는 투여직후 증가하여 24시간 이후 다음 투여전까지 지속적으로 감소되는 패턴이 반복되었고, 최종투여후 1주일경에는 정상수준으로 회복되었다. 반면에 투여가 반복됨에 따라 매 투여직후의 PST의 혈중 최고치는 다소 증가되는 경향을 보였다(20~40 ng/ml). IGF-1의 혈중농도는 투여가 반복됨에 따라 누적적인 증가현상이 뚜렷하였으며, 이후 2주일후 까지도 정상농도보다 높게 유지되었다(200ng/ml). 임상용량 투여군에서 PST 및 IGF-1의 혈중농도는 투여경로에 따른 차이는 나타나지 않았다. 4. 최종(6번째) 투여후 6, 8, 10, 14일에 조사한 간장, 신장, 소장, 근육, 지방 및 주사부위의 조직중의 PST 농도는 6일째에 이미 대조군 수준으로 회복되었다. IGF-1의 경우 최종투여후 6일에는 간장, 신장, 소장, 지방조직에서 정상보다 높은 농도로 잔류하나 이후 14일까지 모두 대조군 수준으로 감소되었다. 5. 이상의 결과는 본 실험에서 사용된 서방형 PST제제는 최소 1주간 유효성이 유지되며, 동시에 PST는 투여 6일째에, IGF-1은 투여후 14일에 정상수준으로 회복됨을 보여주고 있다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
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• pp.78-81
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• 2002

Ferroelectric thin film is a very attractive material for the tunable microwave device applications such as electronically tunable mixers, delay lines, filters and phase shifters. Thin films of $Pb_{x}Sr_{1-x}TiO3(PST)$ were fabricated onto Pt/Ti/SiO2/Si substrate by the sol-gel method. We have investigated the structural and dielectric properties of PST(50/50) thin films for tunable microwave device applications. The PST thin films show typical polycrystalline structure with a dense microstructure without secondary phase formation. Dielectric properties of PST films are strongly dependent on annealing temperature. The dielectric constants, loss and tunability of the PST (50/50) thin films were 404, 0.023 and 51.73 %, respectively.

• 드라이브 ㆍ 컨트롤
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• 제15권3호
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• pp.36-42
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• 2018

Agricultural tractors require frequent shifting to improve operation efficiency, and PST (Powershift Transmission) is considered as a suitable transmission. However, due to the inherent characteristics of the PST, shocks arise during shifting, which imparts a negative effect on the operator. Therefore, in order to improve the transmission performance of the tractor PST, researches on various methods including the hydraulic system circuit, the engine input speed control, and the mechanical system of the transmission are steadily being conducted. In this study, in order to reduce the impact of PST on a shift based on SimulationX software, we analyzed the characteristics of the input signal of PCV (Pressure Control Valve) through sensitivity analysis and verified the simulation model through actual vehicle test. Optimization was performed for minimizing the shift shock for some of the parameters of the input signal at constant temperature and RPM conditions.

• 한국전기전자재료학회논문지
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• 제16권4호
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• pp.286-291
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• 2003

(Pb,Sr)TiO$_3$(PST) thin films have attracted great interest as new dielectric materials of capacitors for Gbit dynamic random access memories. In this study, inductively coupled CF$_4$/Ar plasma was used to etch PST thin films. The maximum etch rate of PST thin films was 740 $\AA$/min at a CF$_4$(20 %)/Ar(80 %) 9as mixing ratio, an RF power of 800 W, a DC bias voltage of -200 V, a total gas flow of 20 sccm, and a chamber pressure of 15 mTorr. To clarify the etching mechanism, the residue on the surface of the etched PST thin films was investigated by X-ray photoelectron spectroscopy. It was found that Pb was mainly removed by physically assisted chemical etching. Sputter etching was effective in the etching of Sr than the chemical reaction of F with Sr, while Ti can almost removed by chemical reaction.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.187-190
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• 2004

In this study, PST thin films were etched with inductively coupled $Cl_2/(Cl_2+Ar)$ plasmas. The etch characteristics of PST thin films as a function of $Cl_2/(Cl_2+Ar)$ gasmixtures were analyzed by using quadrupole mass spectrometer (QMS). Systematic studies were carried out as a function of the etching parameters, including the RF power and the working pressure. The maximum PST film etch rate is 56.2 nm/min, because a small addition of $Cl_2$ to the $Cl_2/Ar$ mixture increased the chemical effect. It was proposed that sputter etching is the dominant etching mechanism while the contribution of chemical reaction is relatively low due to low volatility of etching products.

• 폴리머
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• 제31권1호
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• pp.80-85
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• 2007

Maleic anhydride (MA)와 ethylene-propylene-diene terpolymer(EPDM)를 용액중합으로 말레화 EPDM(MEPDM)을 제조하고 이를 quaternary ammonium silyl Polydimethylsiloxane-TCNQ adduct(PST)와 internal mixer(Rheomix 600P)를 사용하여 용융중합으로 MEPDM-g-PST 공중합체를 제조하였다. 고밀도 폴리에틸렌(HDPE)과 MEPDM-g-PST 공중합체 및 카본블랙 (5, 10, 15 및 20 phr)을 배합하여 MEPDM-g-PST/HDPE/CB 복합체(MPEC)를 제조하였고 HDPE와 카본블랙(5, 10, 15 및 20 phr)을 배합하여 HDPE/CB 복합체(PEC)를 각각 제조하였다. MEPDM-g-PDMS 공중합체의 구조는 FTIR을 이용하여 확인하였으며 MA의 최대 그래프트율은 2.35%이였다. 제조한 복합체의 열적 특성을 측정한 결과 MPEC와 PEC는 유사한 열분해 온도를 나타내었다. MPEC의 인장강도는 카본블랙의 함량이 5에서 20 phr로 증가함에 따라 240에서 372 MPa로 증가하였으며 모폴로지를 분석한 결과 PEC보다 MPEC의 경우에서 카본블랙의 분산이 보다 더 잘 이루어졌음을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.768-771
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• 2004

Pb0.5,Sr0.5TiO3(PST) thin films were deposited on Si with MgO (100) buffer layer by the alkoxide-based sol-gel method. Structural and dielectric properties of PST thin films for the tunable microwave device applications were investigated. For the MgO/Si buffer layer, the PST thin films exhibited highly (100) orientation. The MgO buffer layer affects the stress state of the (100)-oriented PST thin films. The dielectric constant, tunability, and FOM of the highly (100)-oriented PST thin film increased with increasing annealing temperature due to the decrease in lattice distortion. The differences in dielectric properties may be attributed to the change in the film stress. The dielectric constants, dielectric loss and tunability of the PST thin films deposited on the MgO/Si substrates measured at 10 kHz were 822, 0.025, and 80.1%, respectively.