• 천문학회보
• /
• 제44권2호
• /
• pp.56.2-56.2
• /
• 2019

Recently, women astronomers have played increasingly important roles in the International Astronomical Union (IAU). Although only 18% are women across the entire membership of the IAU, currently one half of the IAU Executive Committee members are female. In fact, the previous, current, and next presidents of the IAU and many of the Division presidents are women. I will review a variety of efforts that the IAU has carried out to pursue equality and diversity in Astronomy. Also I will share my personal experience and thoughts on meritocracy as a guiding principle that governs academic integrity and scholarly power system in scientific communities in Korea.

• Nuclear Engineering and Technology
• /
• 제52권12호
• /
• pp.2847-2851
• /
• 2020

A simple water level measurement method based on wavelength division multiplexing (WDM) is proposed and demonstrated. The measurement principle is based on the change of Fresnel reflection occurring at the end facet of the optical fiber tip (OFT). To increase the spatial resolution of water level sensing, a broadband light source (BLS) and an arrayed waveguide grating (AWG) are employed. The OFTs are multiplexed with the dedicated wavelength channels of AWG. By measuring all of the reflection powers reflected at the OFTs with a proposed on-site reflectometer, the water level can be monitored continuously for a fast emergency response. Moreover, it can be implemented easily with the commercially available optical components and devices with the simple configuration.

• 한국유체기계학회 논문집
• /
• 제18권3호
• /
• pp.53-59
• /
• 2015

Tidal turbine, which is relatively similar to wind turbine in term of operational principle, has become a potential solution for the sustainable development of global energy. This paper introduces author's work on tidal turbine which aims to improve the power efficiency by the adaption of counter-rotating concept. The turbine system is modelled and analyzed using computational simulation commercial code. Compared with other works, the counter-rotating tidal turbine presented here is expected to operate stably with high performance throughout a wide range of tip-speed-ratio. Moreover, the equability of individual performance of each rotor is an advantage.

• 조명전기설비학회논문지
• /
• 제26권12호
• /
• pp.56-61
• /
• 2012

There have been a lot of reports about the effects of geomagnetically induced current(GIC) on the power grids. However there has been little domestic efforts made in this relatively urgent area which include academic research or risk assessments on GIC. There still exist a claim that domestic power grids might be in the safe state from GIC since our geomagnetic latitude is low and our power grid is relatively small scale. However it has been already demonstrated that GIC has an effect on power grids located at all latitudes. In this study, we have reviewed the transpiratory principle of the GIC, case studies of the major damage in various regions and we have calculated the GIC that can occur in domestic power grids. This paper presents some of the fundamental information about the risk assessment of domestic power grids from GIC although more thorough investigation should be made to ensure the safe operation of nationwide electric power infrastructure.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
• /
• pp.304-308
• /
• 2001

This paper presents a novel prototype of ZCS-PFM high frequency series resonant inverter using IGBT power module for electromagnetic induction eddy current-heated roller in copy and printing machines. The operating principle and unique features of this voltage source half bridge inverter with two additional soft commutation inductor snubber are presented including the transformer modeling of induction heated rolling drum. This soft switching inverter can achieve stable zero current soft commutation under a discontinuous and continuous resonant load current for a widely specified power regulation processing. The experimental results and computer-aided analysis of this inverter are discussed from a practical point of view.

• 한국콘텐츠학회논문지
• /
• 제5권4호
• /
• pp.54-61
• /
• 2005

우리 경찰이 창설 된지도 올해로 60년이 됐다. 그동안 경찰수사권 독립과 관련된 논의는 창경(創警)이래 지금까지 계속 되고 있는데, 역대 정권들에서 대선 공약의 하나로서 경찰수사권 독립 문제를 거론하였으며, 특히 참여정부의 탄생 과정에서 또 다시 수면 위로 떠올라 큰 이슈가 되고 있다. 수사권과 관련된 문제는 1954년 검찰과 경찰의 지휘관계를 규정한 형사소송법이 '수사의 주재자는 검사(현행 형소법 제195조)' 이며, '경찰은 검사의 수사 지휘를 받아야 한다(현행 형소법 제196조)'는 규정에서 비롯된 것으로 최근 노무현 대통령이 언론사와의 인터뷰를 통해 '대통령이 직접 나서서라도 수사권 문제를 매듭짓겠다'라고 발언한 이래 급물살을 타고 있다. 본 논문에서는 우리나라의 경찰수사권 독립논의의 합리적인 해결책을 모색하기 위하여 대륙법계와 영미법계의 대표적 국가들의 수사권 체제에 관해 살펴보고 인권보장과 권력분립의 원칙에 입각한 보다 비교타당한 수사권 체제에 대해 검토해본다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
• /
• pp.217-221
• /
• 2001

This paper presents a new prototype of soft-switching DC-DC power converter with a high frequency transformer link which has two active power controlled switches in full bridge rectifier with capacitor input type smoothing filter. In this DC-DC converter, ZVS of the inverter in transformer primary side and ZCS of active rectifier area in secondary side can be completely achieved by taking advantage of parasitic inductor component of high-frequency transformer and loss less snubbing capacitors. Its operation principle and salient features are described. The steady-state operating characteristics of the proposed DC-DC power converter are illustrated and discussed on the basis of the simulation results in addition to the experimental ones obtained by 2kw-40kHz power converter breadboard set up.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2008년도 하계학술대회 논문집
• /
• pp.544-546
• /
• 2008

An improved dual-path energy recovery circuit (ERC) using a current source and a voltage source for plasma display panel (PDP) is proposed. The proposed ERC uses the voltage source to charge a panel and the current source to discharge the panel. Thus, the proposed circuit can make the panel charge to $V_S$ and discharge to 0V, fully and it is possible to achieve zero voltage switching (ZVS) of all switches in H-bridge inverter and zero current switching (ZCS) of all switches in the ERC. Moreover, it has less conduction and switching loss in ERC devices by the dual energy recovery paths for charging and discharging the panel. Furthermore, it has features of canceling the gas discharge current, high performance and the low cost ERC components. The operation principle and features of the proposed ERC are presented in detail and verified with 42-inch SD PDP.

• 한국기계가공학회지
• /
• 제19권8호
• /
• pp.73-80
• /
• 2020

The 3D printing of electronics has been a major application topics in additive manufacturing technology for a decade. In this paper, wireless power transfer (WPT) technology for 3D electronics is studied to supply electric power to its inner circuit. The principle of WPT is that electric power is induced at the recipient antenna coil under an alternating magnetic field. Importantly, the efficiency of WPT does rely on the design of the antenna coil shape. In 3D printed electronics, a flat antenna that can be placed on the printed plane within a layer of a 3D printed part is used, but provided a different antenna response compared to that of a conventional PCB antenna for NFC. This paper investigates the WPT response characteristics of a WPT antenna for 3D printed electronics associated with changes in its design elements. The effects of changing the antenna curvature and the gap between the wires were analyzed through experimental tests.

• 전력전자학회논문지
• /
• 제20권6호
• /
• pp.509-516
• /
• 2015

The overmodulation characteristics of a carrier-based medium vector pulse width modulation (CBMVPWM) are examined in this study. CBMVPWM can completely eliminate leakage currents in a three-phase, three-level inverter using only the switching states with the same common mode voltage even in an overmodulation operation. The analytic equations for the magnitude of the output voltage and the switching frequency are derived for overmodulation operation, and the effect of dead time on the leakage current is demonstrated. This study presents the operating principle of CBMVPWM, basic overmodulation features, and simulations and experiments for operating verification.