• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.1047-1049
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• 2001

The displacemant current measuring system used for detecting the dynamic behavior of monolayers at the air-water interface is described. It basically consists of a film balance, a pair of electrodes connected to each other through a sensitive ammeter. Here, one electrode is suspended in air and the other electrode is placed in the water. With Maxwell-displacement-current-measuring method, the phase transitions of Poly-${\gamma}$ -benzyl D-glutamate(PBDG) on a water surface were detected. Measured surface pressure, displacement current and dipole moment of monolayers of PBDG on the water surface. We measured analyzed displacement current that occur when differed temperature. Could know that displacement current is proportional in increase of temperature and great as experiment result.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1530-1532
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• 2001

The displacement current measuring system used for detecting the dynamic behavior of monolayers at the air-water interface is described. It basically consists of a film balance, a pair of electrodes connected to each other through a sensitive ammeter. Here, one electrode is suspended in air and the other electrode is placed in the water. With Maxwell-displacement-current-measuring method, the phase transitons of Poly-$\gamma$-benzyl p-glutamate (PBDG) on a water surface were detected. Measured surface pressure, displacement current and dipole moment of monolayers of PBDG on the water surface. Also, we measured that compression velocity(30, 40, 50[mm/min]) when the sample spread volume was about 400[ul]. From the result, it is known that current is generated in the range of high surface pressures as compression velocity become faster.

• 대한기계학회논문집B
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• 제21권6호
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• pp.779-792
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• 1997

Flow characteristics are numerically investigated when a packet of waves consisting of a Tollmien-Schlichting wave and a pair of Squire waves evolves in a flat-plate laminar boundary layer using a large eddy simulation with a dynamic subgrid-scale model. Characteristics of early stage transitional boundary layer flow such as the .LAMBDA. vortex, variation of the skin friction and backscatter are predicted. Smagorinsky constants and the eddy viscosity obtained from the dynamic subgrid-scale model significantly change as the flow evolves. Far Field noise radiated from the transitional boundary layer shows the dipole and quadrupole characteristics owing to the wall shear stress and the Reynolds stresses, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1413-1415
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• 2002

The Displacement current measurement system used in this experiment because detecting the dynamic behavior of monolayers at the air-water interface is possible. It basically consists of a film balance, a pair of electrodes connected to each other through a sensitive ammeter. Here, one electrode is suspended in air and the other electrode is placed in the water. PBLG phase transformation measured by Maxwell-displacement-current-measurement method in surface of the water. Measured (surfacc pressure, displacement current and dipole moment) of monolayers of PBLG on the water surface. We measured displacement current that occur when changed temperature(15, 20, 25$^{\circ}$ ) and the compression speed(30, 40, 50(mm/min)). From the result, it is known that curren generated in the range of high surface pressur compression velocity and temperature become faste.

• Bulletin of the Korean Chemical Society
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• 제10권2호
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• pp.155-158
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• 1989

The rates of complexation of the 18-C-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) with $K^+,\;Ca^{2+},\;Sr^{2+},\;and\;Ba^{2+}$ in methanol solution have been determined at 25$^{\circ}C$ by a pressure-jump technique. The Eigen Winkler mechanism has been applied to interprete the kinetic data. The results suggest that the rate determining step of the complexation in methanol is the rearrangement of the ligand in the outer sphere ion-dipole pair to form a stable encapsulated complex of the metal ion by the crown ether.

• ETRI Journal
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• 제45권2호
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• pp.203-212
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• 2023

In this study, we developed a co-located and space-shared multiple-input multiple-output (MIMO) antenna module with a modular design and high integration level. The proposed antenna pair includes a half-wavelength loop antenna and a dipole-type antenna printed on the front and back sides of a compact modular board. Owing to their modal orthogonality, these two independent antenna elements are highly self-isolated and free of additional decoupling components, even though they are assembled at the same location and within the same space. Thus, the proposed antenna is attractive in 5G MIMO systems. Furthermore, the proposed co-located and space-shared MIMO antenna module was employed in a 5G smartphone to verify their radiation and diversity performances. A 12 × 12 MIMO antenna system was simulated and fabricated using the proposed module. Based on the results, the proposed module can be employed in large-scale MIMO antenna systems for current and future terminal devices owing to its high integration, compactness, simple implementation, and inherent isolation.

• 대한화학회지
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• 제29권2호
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• pp.104-110
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• 1985

Empirical force-field 방법을 중성자 회절 방법으로 분자구조가 밝혀진 D-sorbitol, CH_2OH\;(CHOH)_4\;CH_2OH$에 적용하여 비교 연구하였다. C-C결합 길이는 계산값과 실험값이 0.009${\AA}$ 내에서 C-O 결합 길이는 0. 023${\AA}$내에서 일치하는 좋은 결과를 얻었다. C-C-C 와 C-C-O 결합 각도는 각각 $2.3^{\circ}$와 $1.9^{\circ}$이내에서 일치하였으나 crystal packing force의 영향을 많이 받고 있는 torsion angle은 상당한 차이가 있었다. C(1)-C(2)-C(3)-C(4) torsion angle을 규칙적으로 변화시키면서 steric 에너지를 연구한 결과 분자의 최저 에너지는 ${\phi}$=+$90^{\circ}$부근에서 나타나 회절법에 의한 결정 구조와는 다른 결과를 얻었다. 그러나 C-O, O-H, O-lone-pair dipole들 간의 상호작용을 무시하면 ${\phi}$=-$60^{\circ}$부근에서 최저에너지를 나타내어 결정구조와 일치 하였다. Empirical force-field 방법의 dipole 상호작용에 관한 에너지항을 개선하면 더 좋은 결과를 얻을 수 있을 것으로 예측 한다.

• 한국분말재료학회지
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• 제27권3호
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• pp.247-255
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• 2020

Recently, interest in technology for eco-friendly energy harvesting has been increasing. Polyvinylidene fluoride (PVDF) is one of the most fascinating materials that has been used in energy harvesting technology as well as micro-filters by utilizing an electrostatic effect. To enhance the performance of the electrostatic effect-based nanogenerator, most studies have focused on enlarging the contact surface area of the pair of materials with different triboelectric series. For this reason, one-dimensional nanofibers have been widely used recently. In order to realize practical energy-harvesting applications, PVDF nanofibers are modified by enlarging their contact surface area, modulating the microstructure of the surface, and maximizing the fraction of the ν-phase by incorporating additives or forming composites with inorganic nanoparticles. Among them, nanocomposite structures incorporating various nanoparticles have been widely investigated to increase the β-phase through strong hydrogen bonding or ion-dipole interactions with -CF₂/CH₂- of PVDF as well as to enhance the mechanical strength. In this study, we report the recent advances in the nanocomposite structure of PVDF nanofibers and inorganic nanopowders.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.61-62
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• 2015

본 논문에서는 분할 링 공진기(SRR; split-ring resonator)를 이용한 소형 이중 대역 슬롯 안테나에 대한 설계 방법을 연구하였다. 제안된 슬롯 안테나는 이중 대역 동작을 위해 SRR 도체를 직사각형 슬롯 내에 장하되었다. SRR 도체와 슬롯 사이의 간격, SRR 도체의 폭의 변화에 따른 입력 반사계수와 이득 특성을 분석하여 최종 설계 변수를 도출하였다. 2.45 GHz WLAN 대역과 3.40-5.35 GHz 대역에서 동작하는 이중 대역 슬롯 안테나를 FR4 기판 상에 $30mm{\times}30mm$ 크기로 설계하였다.

• 한국전자파학회논문지
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• 제21권9호
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• pp.1023-1029
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• 2010

본 논문에서는 PCS, WCDMA, 그리고 WiBro 대역에서 동작하는 이동 통신 기지국용 광대역 편파 다이버시티 안테나를 제안하였다. 본 안테나는 정사각 루프 형태의 다이폴 안테나와 마이크로스트립 급전 구조를 결합하여 설계하였다. 추가적으로 광대역 동작 시 반사판 구조에 의해 발생할 수 있는 방사 패턴 왜곡 현상을 초크(choke) 상자를 이용하여 개선하였다. 설계를 위한 모의 실험은 CST사의 MWS로 해석하였으며, 제작은 비유전율 3.33인 테프론 기판을 이용하여 제작하였다. 측정 결과, 대역폭(VSWR<1.5)은 640 MHz(1.75~2.39 GHz)를 얻었으며, 각 방사체 사이의 격리도는 -25 dB 이하를 얻었다. 그리고 PCS, WCDMA, WiBro 대역에서 최대 이득은 각각 8.9 dBi, 8.2 dBi, 8.6 dBi이다.