• Weed & Turfgrass Science
• /
• 제4권4호
• /
• pp.360-367
• /
• 2015

This study was performed to determine the effects of silicon on zoysiagrass after the application of drought stress. The daily amount of water or scilicon solution was 150 ml per a pot. For 14 days, plants were treated with 0.1 and 1.0 mM silicon (Si) and with distilled water for control and the drought only-treatment. Afterward, the plants in Si and drought treatment were exposed to a 21-day under drought stress condition but the plants in control received water. The results indicated that the growth and the moisture and chlorophyll contents decreased in the drought only-treatment and 0.1 mM Si compared to the control. However, 1.0 mM Si showed an increase in the growth with a significant increase of water and chlorophyll contents. The MDA and $H_2O_2$ concentrations and electrolyte leakage decreased, while the radical scavenging capacity increased in 1.0 mM Si. 1.0 mM Si showed little to no differences in the growth and no differences in water and chlorophyll contents, electrolyte leakage, MDA and $H_2O_2$ concentrations and antioxidant capacity compared to the control. These results suggested that application of silicon is useful for drought tolerance improvement of zoysiagrass under drought that is occurring in turf fields.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 C
• /
• pp.2098-2100
• /
• 2000

We propose pulsed $CO_2$ laser below 30W by the AC(60Hz) switching control of leakage transformer primary which has some advantage of cost and size compared to a typical pulsed power supply. Pulse repetition rate is adjusted from 5Hz to 60Hz to control laser output. In this laser, a low voltage open loop control for high voltage discharge circuit is employed to avoid the HV sampling or switching and high voltage leakage transformer is used to convert rectified low voltage pulse to high voltage one. A ZCS(Zero Cross Switch) circuit and a PIC one-chip microprocessor are used to control gate signal of SCR precisely. The pulse repetition rate is limited by 60Hz due to the frequency of AC line and a high leakage inductance. The maximum laser output was obtained about 23W at pulse repetition rate of 60Hz, total gas mixture of $CO_{2}/N_{2}$/He = 1/9/15, SCR gate trigger angle 90$^{\circ}$, and total pressure of 18Torr.

• 한국정보통신학회논문지
• /
• 제13권12호
• /
• pp.2685-2692
• /
• 2009

펄스형 자기자극장치를 누설변압기의 1차측 스위칭 제어로 교류(60hz) 스위칭 제어를 하여 비용과 크기면에서 기존의 전원장치로 구성된 것보다 약30w의 소용량으로 구성을 할 수가 있었다. 펄스반복률은 자기자극장치의 출력제어를 5-60hz로 적절하게 조절하였다. 이 자석 자극에서는, 고전압 출력 회로를 위한 낮은 전압 열리는 반복 통제가 고전압 표본 추출을 피하기 위하여 채택되며, 또는 스위칭제어와 고전압 누설 변압기는 고전압 하나로 조정된 낮은 전압 펄스를 개조하기 위하여 사용된다. ZCS (영전류스위칭) 회로 및 DSP & FPGA는 SCR의 게이트 신호를 정확하게 통제하기 위하여 사용된다. 펄스 반복 비율은 AC 선과 높은 누설 유도자의 주파수 때문에 60Hz에 의해 제한된다. 최대 자석자극장치의 출력은6 0Hz, 각각 40, 80, 120, $160^{\circ}$, SCR 게이트의 펄스반복 비율로 33W에 관하여 트리거 각 $90^{\circ}$에 대한 전체적인 출력으로 얻어졌다.

• 정보보호학회논문지
• /
• 제22권6호
• /
• pp.1271-1282
• /
• 2012

최근 기업의 기밀정보 및 개인정보의 대량 유출에 따른 보안사고가 지속적으로 발생하고 있다. 이에 내부 정보 유출 방지를 위한 인증 강화와 접근통제 관련 보안 기술이 주목받고 있다. 특히 사용자의 현재 위치정보를 인증 요소로 활용하는 위치기반인증은 접근을 시도하는 사용자의 물리적 통제와 더욱 강력한 인증을 제공하고 내부 정보 유출 경로를 원천적으로 차단할 수 있다는 장점을 가지고 있어 다양한 형태로 제안되고 있다. 그러나 위치정보는 또 하나의 개인 식별 정보로써 인증 수행 시 안전하게 처리되어야 하며, 사용자 위치정보의 특성을 이용하여 유연한 물리적 통제를 수행할 수 있어야 한다. 본 논문에서 제안한 위치기반 인증 기법은 기존 관련 위치기반인증 프로토콜과 비교하여 위치정보 처리 과정의 안정성을 높이고, 최종 사용자 인증에 일회용 패스워드를 사용하여 사용자 인증을 강화한다. 제안된 기법은 내부 정보 유출 방지를 위해 인증 수행과 함께 사용자의 물리적 접근 통제의 개념을 접목시켜 기존 연구보다 높은 보안성을 제공함과 동시에 낮은 통신비용을 보장한다.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1999년도 제29회 춘계학술대회
• /
• pp.197-202
• /
• 1999

A mechanical face seal is a tribe-element intended to control the leakage of working fluid at the interface of a rotating shaft and its housing. The leakage of working fluid decreases as the seal surfaces get closer each other. But a very small seal clearance results in a drastic reduction of seal life because of high wear and heat generation. Therefore, in the design of mechanical face seals the compromise between low leakage and acceptable life is important and presents a difficult design problem. And the gap geometry of seal clearance affects seal performance very much and becomes an important design variable. In this study the Reynolds equation for the sealing dam of mechanical face seals is numerically analyzed using the Galerkin Finite Element Method, which can be readily applied to various seal geometries. The film pressures of the sealing dam are analyzed, including the effects of the seal face coning and tilt. Then, opening forces, restoring moments, leakages, and dynamic coefficients are calculated.

• 한국유체기계학회 논문집
• /
• 제2권3호
• /
• pp.52-58
• /
• 1999

The leakage and rotordynamic coefficients of see-through type gas labyrinth seals are determined using a two-control-volume-model analysis with Moody's wall-friction-factor formula which is defined with a large range of Reynolds number and relative roughness. Jet flow theory are used for the calculation of the recirculation velocity in the cavity. For the reaction force from the labyrinth seal, linearized zeroth-order and the first-order perturbation equations are developed for small motion about a centered position. The leakage and rotordynamic coefficient results of the present analysis are compared with Scharrer's theoretical analysis using Blasius' wall-friction-factor formula and Pelletti's experimental results. The comparison shows that the present analysis using Moody's wall-friction-factor formula and Scharrer's theoretical analysis using Blasius' wall-friction-factor formula give the same results for a smooth seal surface and the range of Reynolds number less than $10^5$.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.799-804
• /
• 2002

In this paper the leakage prediction and rotordynamic analysis of an annular seal with a smooth rotor and spiral-grooved stator are performed. For developing a theoretical model, the three-control-volume analysis of the circumferentially-grooved seal is expanded by considering pressure reduction due to the pumping effect of spiral groove and pressure flow through the spiral groove. Results by the present analysis are compared with available experimental data. For leakage the analysis results generally show a reasonable agreement to the experimental results. For rotordynamic coefficients the analysis results show the same trend as the experimental results for rotor speed with spiral angles, but their magnitudes show somewhat large deviations.

• 전력전자학회논문지
• /
• 제17권6호
• /
• pp.539-545
• /
• 2012

Due to merits cost and efficiency, the transformer-less type photovoltaic (PV) inverters have been popularized in the solar market. However, the leakage current flowing through a parasitic capacitor between PV array and ground can cause adverse effect in the transformer-less PV system. In this paper, a bi-directional PV inverter with high efficiency and low noise is proposed for the PV system with an energy storage device. The proposed inverter is a transformer-less type and performs the bi-directional power control between dc sources and grid with high efficiency. In addition, the proposed inverter can suppress the leakage current and obtain low noise characteristic. Finally, 3-kW prototype was implemented to confirm validity of the proposed inverter.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2017년도 추계 학술논문 발표대회
• /
• pp.217-218
• /
• 2017

Residential apartment underground structures are being utilized for many purposes such as parking lots, community centers, fitness centers, etc. for efficient use of space. However, there are increasing problems of leakage due to various environmental and deterioration conditions. This paper proposes the development of an information network system which can serve as a base to provide solutions, alternatives and technical information for leakage prevention and effective design at the beginning of the construction stage.

• 한국전자통신학회논문지
• /
• 제8권10호
• /
• pp.1515-1521
• /
• 2013

본 논문에서는 저항성 누설전류, 과전류, 대기전력 차단기능을 갖는 지능형 콘센트와 연동하는 안드로이드 운영체제의 전력관리 어플리케이션을 개발한다. 개발된 전력관리 어플리케이션을 이용하면 언제, 어디서나 콘센트에서 발생될 수 있는 누전으로 인한 전기화재 및 감전 등을 모니터링하고, 콘센트에 공급되는 전력을 제어하여 실내의 가전기기에 대한 ON/OFF 제어 및 낭비되고 있는 대기전력을 손쉽게 차단할 수 있도록 하였다.