• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.4
• /
• pp.1474-1479
• /
• 2012

Rotational smart lighting control system provides artificial light to plants on planting board by rotational lighting system. As the lighting system of existing plant factory has high cost problem due to the installation for many lighting equipments, the lighting system was developed to rotate less number of lighting equipments to reduce cost. In this paper, the illuminance, luminous flux and photosynthetic photon flux density(PPFD) that plants need to grow were calculated. And the light intensity at each measured location considering the rotational speed of blade were analyzed by the simulation and the experiment.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2004.05b
• /
• pp.932-936
• /
• 2004

수제는 하천에서의 흐름 방향과 유속을 제어하여 하안 또는 제방을 유수에 의한 침식작용으로부터 보호하기 위해 호안 또는 하안 전면부에 설치하는 구조물이다. 수제를 설치하는 목적은 하안 및 제방의 보호, 유로의 제어, 그리고 수환경의 개선 등을 들 수 있다. 국내에는 해방 이후 수제의 시공 사례가 거의 없었으나, 최근 들어 자연형 하천파 하천생태계 복원에 대한 관심이 점증하면서 수제에 대한 관심이 커지고 있다. 그러나 현재 국내에는 수제설계에 대한 실증적인 지침이 미비하고 국외의 기준을 검증 없이 소개하는 수준이어서 현장의 설계단계에서 수제공의 채택을 망설이게 하는 원인이 되고 있다. 이 연구에서는 국내${\cdot}$외 수제의 현황과 기술 동향을 파악하여 수제의 기하학적 특성인 수제길이, 수제길이, 그리고 설치각도의 3가지 설계인자를 조합하여 실험을 실시하였다. LSPIV 기법을 적용하여 측정한 유속자료를 분석한 결과 수제역 내 평균유속이 유입부 유속에 비해 $40\%$ 이하로 감소하는 것을 관찰할 수 있었다. 유속성분을 통하여 수제역 내 와도 및 사분면 검토를 실시한 결과 수제역 내에서는 비교적 안정적인 수치를 보이고 있어 호안침식방지에 유리한 것으로 보인다. 수제의 길이가 하폭의 $15\%$ 이하인 경우 상향 또는 하향수제가, $20\%$ 이상인 경우 직각수제가 유리한 것으로 나타났다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.237-237
• /
• 2019

현재 한반도에서는 대규모 하천정비가 지속적으로 진행되고 있다. 그 결과 하천은 평형상태를 맞추기 위하여 여러 가지 현상들이 발생하는데, 대표적인 현상 중 하나는 세굴현상이 있다. 이는 하천의 호안, 교각, 교대 등에 일어나 구조물의 안전성을 떨어뜨리고 큰 피해를 발생시킬 수 있다. 이러한 문제를 해결하기 위해서 설치 할 수 있는 구조물이 날개공이다. 본 연구에서는 곡선수로의 연속식, 흐름 방향의 운동방정식 및 와도 방정식을 수치모의기법을 통해서 날개공의 위치 및 개수, 크기, 각도, 간격 등에 따라 유속의 변화를 살펴보고 그에 따른 외안부근에서의 하상변화를 분석하였다. 분석 결과 날개공을 일정 간격별로 설치 하였을 때 개수에 따라 각각 날개공으로 인한 유속 및 수면유속의 감소가 크게 일어났고, 유속감소로 인해 하천의 횡단 방향하상 단면의 변화가 줄어들어 세굴현상이 감소되는 결과가 나왔다. 또한 날개공의 크기 및 모형에 따라서도 유속 및 수면 유속등의 큰 차이가 생겨 이에 따라 세굴 현상이 감소되는 결과가 나왔다. 본 연구 결과를 발전시켜 실제 하천에 적용할 수 있는 날개공 설치의 가이드라인을 제시한다면 현재 대규모하천정비에 따른 많은 문제점들을 해결할 수 있을 것이다.

• Journal of the Institute of Convergence Signal Processing
• /
• v.14 no.2
• /
• pp.99-104
• /
• 2013

Replacement of sensor nodes for monitoring a wide range area such as mountains and forests needs a lot of time and cost. Using new and renewable energy around them can maximize the lifetime of wireless sensor networks, in which solar energy is infinite energy source that is available in 365 days. To design these sensor networks, solar energy model is essential and to estimate and analyze the overall photovoltaic energy. Using this, we can figure out important data such as the size and performance of solar panel needed. However, existing researches for solar energy harvesting consider parts of many factors to influence the quantity of solar energy gathered. In this paper, we suggest advanced solar energy harvesting model considering angular loss (solar cell panel), overheat loss (solar cell), rechargeable battery heat and cooling for each monthly properties. From our experimental results according to outdoor temperature, panel angle and the surface temperature of solar panel, we show these impact factors are correctly configured.

• Journal of Korean Society of Transportation
• /
• v.26 no.1
• /
• pp.203-213
• /
• 2008

U-Turn offers convenience to drivers. U-Turn increases efficiency of traffic flow. But Standard of U-Turn is not clear. It caused many problems of traffic flow and traffic safety. This study estimate length between U-Turn location with front intersection based on stopping sight distance and left-turn vehicle's queue length. Variables are used traffic volume and operation speed. This study Analysis of U-Turn vehicle's behaviors and classification of conflict form by investigation. U-Turn length estimating based on relationship analysis between conflict with U-Turn length. Variables are used lane changing angles and operation speed. This study estimates length between U-Turn location with back intersection based on gap acceptance theory. Variables are used traffic volume, operation speed and lane changing angles. So, U-Turn location and length estimated considering traffic flow and traffic safety.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.2
• /
• pp.672-680
• /
• 2017

A solar photovoltaic system is composed of a module mounting structure, supporting trunk, and a control unit that supplies generated electrical power to an external power grid or a load. The efficiency of the system depends on the incident solar light, so the mounting structure is installed to face the sun. However, because the sun always moves, systems that track the sun have better efficiency than fixed systems. The structure experiences wind pressure, snow load, seismic load, and structure weight. The wind pressure has the most serious effect on the structure. The pressure was obtained using finite element method for various gaps between modules and angles between the panel and the ground. The wind pressure is lowest when the gap is zero, and it increases with the inclination angle. Based on the results, a mounting structure module was designed.

• Journal of the Korean Solar Energy Society
• /
• v.27 no.4
• /
• pp.121-128
• /
• 2007

Convective heat loss from solar tower receiver is experimentally investigated in wind tunnel with tilt angles and operating conditions. In order to simulate the receiver, an electric heater, which is made of aluminum (width : 100 mm, height : 100mm) is used and installed in the wind tunnel. The convective heat loss from the receiver is dependent on the direction and the velocity of the wind and the surface temperature of the receiver. The tilt angle and surface temperature of the receiver are varied from 0o (cavity facing straight down) and 90o(cavity aligned horizontally) and from $150^{\circ}C$ to $250^{\circ}C$, respectively. Also, the wind speed is changed from 0 to 4m/s. The convective heat loss is obtained by measuring consumed power to the heater to maintain the desired surface temperature. It is concluded that Nusselt number increases with increasing wind speed for all cases. Especially, it is showed that Nusselt number can be maximized when the tilt angle is 30o.

• Journal of the Korean GEO-environmental Society
• /
• v.8 no.2
• /
• pp.29-39
• /
• 2007

In this study, the centrifugal tests were fulfilled to analyze the displacement characteristics caused by the embankment construction on soft ground. Embankment of height, undrained shear strength and with or without geotextile were selected to evaluate the displacement characteristics of soft ground by embankment. As a result, the replacement section without geotextile showed the parabola shape. The replacement section with geotextile showed the trapezoidal shape which represents the uniform settlements. The replacement angle is increasing nearly lineally with increasing the height of embankment and G-level. The position, where the maximum horizontal displacement occurred, was between $0.24H_0$ and $0.35H_0$ and was at $0.3H_0$ on the average. In the case of with and without geotextile, the relationship between the maximum settlement of ground(S) and maximum horizontal displacement(${\delta}_m$) was ${\delta}_m$ = 0.60S, ${\delta}_m$ = 0.54S, respectively.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.1
• /
• pp.63-70
• /
• 2019

The number of vehicle-to-barrier collisions has increased due to improved driving environments. In addition, it is reported that the number of accidents led to impact severity larger than current capacity of a median barrier has increased. It is required to develop a high performance median barrier in order to secure expressway safety. This paper aims at proposing impact loading model and locations for a high performance median barrier based on analysis of median-barrier-related accident history. The SB6 test level (Impact severity: 420 kJ, Mass: 25 ton, Impact speed: 80 km/h, Impact angle: $15^{\circ}$) was suggested for target impact severity based on statistical data analysis. The suitable locations also were proposed from investigation of driver behaviors for installation and rehabilitation of high performance median barrier.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.4
• /
• pp.195-200
• /
• 2015

The thermal performance in the channels with two-wall rectangular convergent/divergent cross-sectional areas along the axial distance was investigated experimentally. The ribbed rectangular convergent/divergent channels were manufactured with a fixed rib height (e) = 10 mm and the ratio of rib spacing (p) to height (e) = 10. Three different parallel angled ribs (a = $30^{\circ}$, $45^{\circ}$, and $60^{\circ}$) were each placed on the channel's one sided wall only. The convergent channel of $D_{ho}/D_{hi}=0.67$ and the divergent channel of $D_{ho}/D_{hi}=1.49$ were considered. The ribbed divergent channel produced better thermal performance than the ribbed convergent channel in three different restrictions; identical flow rate, identical pumping power, and identical pressure loss.