• 한국해안해양공학회:학술대회논문집
• /
• 한국해안해양공학회 2002년도 한국해안해양공학발표논문집 Proceedings of Coastal and Ocean Engineering in Korea
• /
• pp.208-211
• /
• 2002

The Kyunggi Bay (125-l28E, 36-38N) is a macro-tidal bay in the western central port of Korean Peninsula(Fig. 1). The Bay characterizes its feature as wide tidal flats, deep tidal channels and tidal sand ridges running in parallel to tidal flows. The macro-tidal range (up to approximately 8.6m) and consequent strong tidal currents erode the bottom sediment and selectively transport to the low-energy area forming tidal ridges or tidal flats. (omitted)

• Applied Science and Convergence Technology
• /
• 제25권1호
• /
• pp.7-14
• /
• 2016

Nanoplasmonics is a developing field that offers attractive optical, electrical, and thermal properties for a wide range of potential applications. Based on the compelling characteristics of this field, researchers have shed light on the possibilities of integrated photonics and biosensing platforms using nanoplasmonic principles. Single and unique nanostructures with plasmons can act as individual transducers that convert desired information into measurable and readable signals. In this review, we will discuss nanoplasmonic sensors, especially those in relation to photodetectors for future optical interconnects, and bioinformation sensing platforms based on nanoplasmonics, thus providing a viable approach by which to create sensors corresponding to target applications. In addition, we also discuss scalable fabrication processes for the creation of unconventional nanoplasmonic devices, which will enable next-generation plasmonic devices for wearable, flexible, and biocompatible systems.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제10권2호
• /
• pp.143-151
• /
• 2010

In this work, we propose a single electron memory 'SEM' design which consist of two key blocs: A memory bloc, with a voltage source $V_{Mem}$, a pure capacitor connected to a tunnel junction through a metallic memory node coupled to the second bloc which is a Single Electron Transistor "SET" through a coupling capacitance. The "SET" detects the potential variation of the memory node by the injection of electrons one by one in which the drainsource current is presented during the memory charge and discharge phases. We verify the design of the SET/SEM cell by the SIMON tool. Finally, we have developed a MAPLE code to predict the retention time and nonvolatility of various SEM structures with a wide operating temperature range.

• 한국진공학회지
• /
• 제5권1호
• /
• pp.85-92
• /
• 1996

The external electricla characteristics of helicon wave plasmas were measured over a wide range of RF power and magnetic filed. External parameters. such as antenna voltage , current, phase shift, and interanl parameter, electron density were measured at 7MHz, 1mTorr Ar discharge . The equivalent discharge resistance and reactance, and the power transfer efficiency were calculated through these measurements. There are a helicon mode which produces high density plasma by helicon wave and a lowmode which produces low density plasma by capaictive electric field. In case of the helicon mode, the anternna voltage and current were lower than those of the low-mode. The phase difference between voltage and current decreased suddenly at the transition point from the low-mode to the helicon mode. Equivalent resistance and power efficiency increased and reactance decreased suddenly at the transition point. These results mean that the power transperred to plasma and the nutual coupling between the antenna and plasma increase as the mode changes from the low-mode to the helicon mode.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제25권4호
• /
• pp.312-326
• /
• 2021

The prey-predator model is one of the most influential mathematical models in ecology and evolutionary biology. In this study, we considered a modified prey-predator model, which describes the rate of change for each species. The effects of modifications to the classical prey-predator model are investigated here. The conditions required for the existence of the first integral and the stability of the fixed points are studied. In particular, it is shown that the first integral exists only for a subset of the model parameters, and the phase portraits around the fixed points exhibit physically relevant phenomena over a wide range of the parameter space. The results show that adding coupling terms to the classical model widely expands the dynamics with great potential for applicability in real-world phenomena.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2019년도 전력전자학술대회
• /
• pp.352-353
• /
• 2019

자기유도 무선전력 전송 (Inductive Power Transfer, IPT) 시스템에서 송 수신패드의 결합계수 k는 송신패드와 수신패드의 이격거리에 따라 가변된다. 송 수신패드의 결합계수에 따라 IPT 컨버터의 동작특성이 바뀌기 때문에, 일반적인 스위칭 주파수 제어 방법으로는 IPT 컨버터의 정상 동작 영역이 제한된다. 본 논문에서는 송 수신패드의 결합계수 계수에 따라 풀브릿지 구조의 IPT 컨버터 1차 측을 풀브릿지 또는 하프브릿지로 제어하여 동작 가능한 결합계수 범위를 확장할 수 있는 제어 방법을 제안하고, LCCL-S 구조의 IPT 컨버터에 적용하여 실험을 통하여 제어 방법의 타당성을 검증한다.

• Structural Monitoring and Maintenance
• /
• 제11권2호
• /
• pp.149-171
• /
• 2024

Drive-by monitoring (also known as indirect monitoring or mobile sensing) of bridges has obvious advantages when compared to other approaches of Structural Health Monitoring. The underlying concept involves leveraging the coupling between the vertical vibrations of the bridge and those generated in the passing vehicle. In this scenario, the vehicle serves as both the initiator and recipient of the vibrations, which can provide information on the structural condition of the bridge. In the literature, a wide range of methods has been proposed, primarily focused on highway bridges. However, limited research has been published to assess the suitability of indirect methods for monitoring railway bridges, bounded to numerical studies based on theoretical simulations and, rarely, on experimental investigations. The aim of this work is to contribute to filling this gap and explore the feasibility of implementing drive-by monitoring for railway bridges using in-service vehicles and discuss its potential applicability, from theoretical and practical point of view, with illustration through real case studies from the Moroccan railway network.

• Journal of Electrical Engineering and Technology
• /
• 제11권6호
• /
• pp.1656-1663
• /
• 2016

A capacitive wireless power transfer (C-WPT) system uses an electric field to transmit power through a physical isolation barrier which forms a pair of ac link capacitors between the metal plates. However, the physical dimension and low dielectric constant of the interface medium severely limit the effective link capacitance to a level comparable to the main switch output capacitance of the transmitting circuit, which thus narrows the soft-switching range in the light load condition. Moreover, by fundamental limit analysis, it can be proved that such a low link capacitance increases operating frequency and capacitor voltage stress in the full load condition. In order to handle these problems, this paper investigates optimal design of double matching transformer networks for C-WPT. Using mathematical analysis with fundamental harmonic approximation, a design guideline is presented to avoid unnecessarily high frequency operation, to suppress the voltage stress on the link capacitors, and to achieve wide ZVS range even with low link capacitance. Simulation and hardware implementation are performed on a 5-W prototype system equipped with a 256-pF link capacitance and a 200-pF switch output capacitance. Results show that the proposed scheme ensures zero-voltage-switching from full load to 10% load, and the switching frequency and the link capacitor voltage stress are kept below 250 kHz and 452 V, respectively, in the full load condition.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2009년도 춘계학술대회 논문집
• /
• pp.107-110
• /
• 2009

연소불안정현상은 주로 음향파와 열방출률 섭동간의 상호작용에 의해 발생한다고 알려져 있다. 이러한 현상은 헬름홀츠 공진기와 같은 수동제어기를 사용하여 감소시킬 수 있다. 그러나 헬름홀츠 공진기는 일반적으로 좁은 주파수대역에 대해서만 효과가 있는 단점을 가진다. 따라서 본 연구에서는 다양한 작동 범위에서 효과를 가질 수 있도록 피스톤을 사용하여 헬름홀츠 공진기의 부피를 변화시켜가며 연소불안정현상에 적용하였다. 그 결과 피스톤을 최적위치에 동조시킴으로써 연소 불안정 모드의 진폭을 감소시킬 수 있었다. 또한 이러한 결과를 바탕으로 능동적으로 동조되는 수동제어방식의 가능성에 대해서 알아보고자 한다.

• 대한전자공학회논문지SD
• /
• 제37권4호
• /
• pp.53-59
• /
• 2000

광섬유-평면도파로 결합기의 편광선택성을 이용한 새로운 구조의 광섬유형 편광기를 설계 및 제작하였다. 금속클래드-평면도파로의 높은 복굴절을 이용함으로서 동작 파장범위를 증가시킬 수 있었다. 평면도파로의 코어층으로 폴리머를, 클래딩으로 금(Au)을 각각 사용하였다. 실험결과는 평면도파로의 두께를 조절하여 TE편광 혹은 TM 편광이 만들어 질 수 있음을 보인다. 16㏈ 이상의 편광소멸비를 만족하는 파장범위는 130nm 이상으로 나타났고 삽입손실은 0.5㏈ 정도였다.