• 한국해안·해양공학회논문집
• /
• 제23권4호
• /
• pp.292-303
• /
• 2011

본 연구에서는 현재 전 세계적으로 해안선 회복공법의 주류가 된 연성방어 중 하나인 샌드바이패싱을 위한 새로운 시스템을 제안하고자 한다. 검증을 위하여 경제성을 고려한 연구장비를 설계 및 제작하였다. 본 장비의 모래 토출율 예측은 일반적인 하천준설 시스템에 적용시켜 정류상태에서 시간당 토출된 물과 토사 무게를 측정 분석하는 방법으로 수행했다. 자료의 분석 결과, 본 시스템은 이론치에 약 9.6% 차이로 근접한 618 ton/hr의 토출율을 나타냈다. 본 토사류는 고밀도 흐름으로 가정했을 때 비교적 높은 수준으로 예측이 가능함을 알았다. 현장실험에 의한 토출율을 기초로 모래의 토출부피를 예측하였다. 본 시스템과 동일한 400 HP 엔진, 흡입 파이프 300 mm (12 inch), 토출 파이프 250 mm(10 inch)인 미국 플로리다 South Lake Worth Inlet에 설치되어 있는 고정식 샌드바이패싱 장비는 함미비가 20% 수준이며 토사 토출율이 $110\;m^3/hr$이다. 본 연구에서 제안된 장비의 펌핑 능력은 함미비가 동일할 때, 플로리다 설비와 거의 유사한 토사 효율이 $103\;m^3/hr$로 예측된다. 본 장비는 플로리다에 설치된 고정식이 아니며 친수성을 고려한 이동식 형태이다. 플로리다 South Lake Worth Inlet 설비의 샌드바이패싱 단가는 미화 8~9 달러/$m^3$이다(Brunn, 1993). 본 시스템은 모래량이 적은 경우에 적절하며 이동을 위한 별도의 장비가 필요하지 않으므로 경제적이고 운행을 위해 25~30 l/hr의 경유가 소모된다. 많은 양의 모래이동을 위해 다수의 소형장비를 동시에 운영하는 시스템은 추후 연구대상이 될 것으로 기대된다.

• 한국세라믹학회지
• /
• 제34권3호
• /
• pp.225-232
• /
• 1997

고율 방전용 Li/SOCl2전지의 성능은 카본 양극에 의해 크게 영향을 받는다. 전지가 방전되는 동안 SOCl2의 환원은 다공성 카본 양극에서 일어나고 기공내에 방전반응 생성물-주로 LiCl-이 석출된다. 이러한 현상으로 양극 표면이 부동화되어 전지의 성능이 제한된다. 양극이 성능을 향상시키기 위해 양극이 표면밀도와 두께를 각각 변화시켜 양극 반쪽셀 정전류 방전실험(50mA/$\textrm{cm}^2$)을 행하였다. 실험 결과 0.04g/$\textrm{cm}^2$, 두께 1.4mm의 양극이 가장 좋은 특성을 보였다. 표면 밀도가 0.04 g/$\textrm{cm}^2$로 일정하고 두께가 0.8mm, 1.4mm의 양극에서 분극현상은 두께가 두꺼운 1.4mm양극에서 감소하였으며 방전경과시간과 방전용량(Ah/$\textrm{cm}^2$)이 증가하였다. 두 양극에 대한 기공률 측정 결과 두께 1.4mm양극이 두께 0.8mm양극보다 전체 기공부피가 크고 전지성능과 연관되는 mesopore(0.05 $\mu$m~0.5$\mu$m)와 macropore(>0.5$\mu$m)부피가 더 증가하였다. 방전 후 카본 양극의 표면분석 결과 등방결정과 판상구조 집합체 형태의 LiCl과 소량의 S를 확인하였다.

• 조명전기설비학회논문지
• /
• 제30권1호
• /
• pp.72-78
• /
• 2016

In terms of power components which use environmentally-friendly dry air that can substitute SF6, there have been studies on the electrical properties of the solid insulation "spacer" for the purpose of securing dielectric strength as they become smaller. This study laminated solid insulation to keep the creeping distance the same in the dry air and investigated vertical surface discharge characteristics by shape. The three sheets of disk-type solid insulation(Bakelite) were laminated in a manner to keep the creeping distance the same. The lamination was categorized as follows: "Type A" in which the insulations with the same disk diameter were laminated; "Type B" in which the insulations whose middle disk diameter was large were laminated; and "Type C" in which the ones whose middle disk diameter was small were laminated. For a vertical surface discharge experiment, dry air was injected into the test chamber depending on the shape of the laminated solid insulation, and chamber pressure was adjusted in a range of 0.1-0.6MPa. As volume decreased, surface discharging voltage by unit volume increased. This was because of dielectric polarization according to the structural characteristics of the shape of lamination. The highest surface discharging voltage was found in "Type C."

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 D
• /
• pp.1786-1788
• /
• 1999

In this paper, we studied Surface Discharge Type Flat Fluorescent Lamp with High Luminance for LCD Backlighting, Liquid Crystal display(LCDs) demand the use of fluorescent lamp as the backlighting source. This lamp is Surface Discharge Type structure with a pair of Sodalime glass, insulator layer, phosphor layer, and Xe gas gap. In spite of its simple structure, the lamp has uniform and stable discharge over entire volume. Till now, we measured the current-voltage(V-I), Firing Voltage, Sustain Voltage for 0.5mm, 1mm electrode gap. In experiment result, long gap cell structure cause high firing voltage. The rising in firing voltage in long gap structure could not be explained by paschen's law because of non-uniform electric field.

• 한국진공학회지
• /
• 제15권2호
• /
• pp.117-138
• /
• 2006

지표면에서 플라즈마는 전기방전에 의하여 만들어낸다. 그래서 대부분의 플라즈마 발생은 1백만분의 1기압보다 더 낮은 기압에서 발생하고 있었다. 그러나 많은 플라즈마 응용은 고기압에서 발생한 플라즈마를 요구하고 있다. 진공펌프와 같은 고가의 장비를 피하기 위하여 과학자들은 1기압이나 그이상의 압력에서 플라즈마를 발생하는 연구를 하기 시작했다. 많은 량의 제료 공정, 환경보호와 개선, 그리고 고효율 에너지 창출과 이용 등의 분야에 플라즈마를 사용할 때에는 오직 더 많은 량의 플라즈마를 더욱 값싸게 만들 때에만 가능한 것이다. 우리는 따라서 고기압에서 플라즈마를 만들어내는 새로운 방법을 개발하고 이러한 플라즈마가 21세기 산업에 적용될 수 있는 새로운 기반을 구축하는 연구를 수행하고 있다. 이러한 기술은 미래의 재료 공정이나, 환경 그리고 에너지 분야에 지대한 영향을 미칠 것으로 생각한다.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2006년도 학술발표회 논문집
• /
• pp.1666-1670
• /
• 2006

The purpose of this study is to analyze how a downstream channel is affected in case of hypothetical dam failure. The object of it is Hwacheon dam basin within the basin of North Han river. This study has analyzed the influence on Pyeonghwa(Peace) dam and Hwacheon dam supposing that the Imnam dam in North Korea on the upper stream of North Han river is failed hypothetically at the MFWL(maximum flood water level) by a deluge of rain. The model applied at the main study is NWS(National Weather Service) FLDWAV(Flood Wave Routing Model). Dam breach characteristics data are analyzed by making nine hypothetical scenarios on the basis of other studies on the shape and size of dam breach, time of failure and so on. Expected peak discharge through the breach is verified to have the propriety in comparison with empirical function which is developed on the basis of the case of dam breach in the foreign countries and it is observed that peak discharge is more increasing, as the time of breach gets shorter and the breach width gets bigger. As a result of main study, even though the Imnam dam is hypothetically failed down, there has no influence on the Hwacheon dam of the downstream as the extended Pyeonghwa dam on the downstream controls the volume of discharge properly.

• 한국농공학회지
• /
• 제40권2호
• /
• pp.81-91
• /
• 1998

Water level of irrigation reservoir during the flood season could be kept to a certain level, so called, flood control level by releasing the flood inflow in advance in order to reduce the peak discharge of next coming flood and the damage of inundation. Concept of restriction intensity of water supply was introduced to evaluate the influence of flood control volume on the irrigation water supply. Restriction intensity can be calculated by multiplying the ratio of restriction to the days of restriction which are obtained from the operation rule curve and daily water level of irrigation reservoir and it has the dimension of % day. The method of restriction intensity was applied to the Yedang irrigation reservoir with the observed data of 30 years to review whether the present flood control volume is reasonable or not, and suggest the optimal flood control volume, if possible.

• 한국정밀공학회지
• /
• 제26권4호
• /
• pp.55-63
• /
• 2009

This paper reports on the theoretical and experimental study of the pressure ripples in a pressure unbalanced type vane pump which have widespread use in industry. Because they can infinitely vary the volume of the fluid pumped in the system by a control. Pressure ripples occur due to the flow ripples induced by geometry of side plate, leakage flow, reverse flow from the outlet volume produced by pressure difference between pumping chamber and outlet volume when the pumping chamber connected with the outlet volume. In this paper, we measured the pressure variation of a pumping chamber, reaction force on a cam ring, the mathematical model for analyzing the pressure ripples which included vane detachment and fluid inertia effects in notch area has been presented, and was applied to predict the level and the wave form of the pressure ripples according to operating conditions.

• 설비공학논문집
• /
• 제29권12호
• /
• pp.628-637
• /
• 2017

This study was conducted to present an effective control method for the common duct system to uniformly discharge volume flow rate exhausted from the kitchen and bathroom of each household in an apartment regardless of the position of household. Since the common duct system is installed vertically and the ventilator is installed in the terminal, the static pressure of each household decreases when vertical height increases. Therefore, the volume flow rate exhausted from each household is different. In order to improve such a phenomenon, a constant air volume damper shall be installed in a branch duct coupled with a common vertical duct system. The selected ventilator should also be able to handle the maximum volume flow rate considering diversity factor. Therefore, a uniform volume flow rate must be exhausted from all households where the hood is operated. This paper mainly focuses on suggestion of an optimum exhaust control method by comparing exhaust performance of each household according to the presence or absence of a constant air volume damper.

• 전기학회논문지
• /
• 제61권2호
• /
• pp.237-242
• /
• 2012

In this paper, we investigated effects of ITO electrode geometry and dielectric layer thickness on the discharge Characteristic of AC PDP. As the dielectric thickness is decreased ($30{\sim}12{\mu}m$), firing and sustain voltage is decreased. Luminance and discharge power increase with decreasing dielectric layer thickness because of increasing capacitance between plasma and electrodes. Reactive power decreases with dielectric thickness due to reduced capacitance between sustain electrodes. For the high Xe test panel with small ITO electrode, luminous efficacy as well as luminance increase with decreasing dielectric layer thickness. This result suggest that high power density and small plasma volume is beneficial for high efficacy discharge.