• 한국인터넷방송통신학회논문지
• /
• 제18권6호
• /
• pp.207-212
• /
• 2018

태양광발전시스템에 대한 시험인증 기술력 향상을 위한 표준화를 위하여 기 구축된 분야에 대한 국가표준(안)을 제안 및 개정하고, 기업이 수출시 상대국이 인정하는 적합성평가(CB인증)가 국내에서 지원하는 것이 필수적이다. 이를 위하여 국제공인 적합성평가 기관으로서의 능력을 향상시켜 IECEE-CB 제도에 의한 인증기관(NCB-NREC) 및 시험기관으로의 위상 강화를 추진하여 국내기업이 수출장벽을 타개하고 외국에서 시험인증 받기 위한 기간을 단축하고 경비를 대폭 절감하여 수출의 증대 및 대외 경쟁력 확보가 필요하다. 또한 정부가 추진 중인 FTA에 교역시 기술장벽(TBT) 해소를 위한 상호인정 협정에 대비하기 위하여도 국내 시험인증기관의 능력향상이 필수적이다. 현재 태양광모듈 및 인버터의 안전성 평가는 유럽 및 일본에서 강제로 채택하여 국내업체 수출시 외국인증기관을 이용하고 있는 실정으로서 태양광모듈의 안전성 평가에 대한 CBTL를 취득함으로서 국내외 경쟁력 강화 및 태양광 발전 사업을 수출산업으로 육성지원 하는데 기여할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제15권11호
• /
• pp.4244-4274
• /
• 2021

The utilization of UAVs in various fields has led to the development of flying ad hoc network (FANET) technology. In a network environment with highly dynamic topology and frequent link changes, the traditional routing technology of FANET cannot satisfy the new communication demands. Traditional routing algorithm, based on geographic location, can "fall" into a routing hole. In view of this problem, we propose a geolocation routing protocol based on multi-agent reinforcement learning, which decreases the packet loss rate and routing cost of the routing protocol. The protocol views each node as an intelligent agent and evaluates the value of its neighbor nodes through the local information. In the value function, nodes consider information such as link quality, residual energy and queue length, which reduces the possibility of a routing hole. The protocol uses global rewards to enable individual nodes to collaborate in transmitting data. The performance of the protocol is experimentally analyzed for UAVs under extreme conditions such as topology changes and energy constraints. Simulation results show that our proposed QLGR-S protocol has advantages in performance parameters such as throughput, end-to-end delay, and energy consumption compared with the traditional GPSR protocol. QLGR-S provides more reliable connectivity for UAV networking technology, safeguards the communication requirements between UAVs, and further promotes the development of UAV technology.

• Nuclear Engineering and Technology
• /
• 제56권1호
• /
• pp.301-308
• /
• 2024

Ceramic materials are being explored as alternatives to toxic lead sheets for radiation shielding due to their favorable properties like durability, thermal stability, and aesthetic appeal. However, crafting effective ceramics for radiation shielding entails complex processes, raising production costs. To investigate local viability, this study evaluated Malaysian ceramic tiles for shielding in diagnostic X-ray rooms. Different ceramics in terms of density and thickness were selected from local manufacturers. Energy Dispersive X-ray Fluorescence (EDXRF) and X-ray Fluorescence (XRF) characterized ceramic compositions, while Monte Carlo Particle and Heavy Ion Transport code System (MC PHITS) simulations determined Linear Attenuation Coefficient (LAC), Half-value Layer (HVL), Mass Attenuation Coefficient (MAC), and Mean Free Path (MFP) within the 40-150 kV energy range. Comparative analysis between MC PHITS simulations and real setups was conducted. The C3-S9 ceramic sample, known for homogeneous full-color structure, showcased superior shielding attributes, attributed to its high density and iron content. Notably, energy levels considerably impacted radiation penetration. Overall, C3-S9 demonstrated strong shielding performance, underlining Malaysia's potential ceramic tile resources for X-ray room radiation shielding.

• 한국멀티미디어학회논문지
• /
• 제8권3호
• /
• pp.336-344
• /
• 2005

본 논문에서는 개선된 동적 윤곽선 모델을 이용하여 높은 시간 해상도를 가진 EBT 폐 영상에서 폐실질 영역을 검출하였다. 기존의 동적 윤곽선 모델에서 물체의 경계선을 얻기 위한 방법은 에너지 최소화 형태로서 내부에너지와 외부에너지를 조절함으로써 검출되어 질 수 있다. 그러나 이 방법에서는 초기화 지정 문제나 내부 에너지의 탄성과 구부러짐의 특성 때문에 요면 영역에 대하여 빈약한 수렴성 등의 문제점들을 가지고 있다. 본 논문에서는 이러한 요면 문제들을 해결하면서 폐실질 영역으로 수렴시키기 위해 윤곽선 상에 있는 제어 점들을 이웃 점들과 함께 각각 수직 이등분선 상의 한점에 이동시킴으로써 내부 에너지를 조절하고, 입력받은 영상의 에너지를 나타내는 외부에너지와 함께 에너지를 최소화시킴으로써 원하는 폐실질 영역에 윤곽선이 수렴할 수 있도록 하였다. 요면 영역에 대한 수렴은 이런 내부에너지에 의해 효과적으로 구현 될 수 있었고, 하나의 초기 윤곽선에서 다중 물체들도 검출될 수 있어서 의료 영상에서의 폐실질 영역 검출에 효과적으로 적용될 수 있음을 확인할 수 있었다.

• 한국정밀공학회지
• /
• 제27권11호
• /
• pp.46-56
• /
• 2010

The present research works investigated into the low velocity impact characteristics of DP 780 high strength steel sheet with 1.7 mm in thickness subjected to free boundary condition using three-dimensional finite element analysis. Finite element analysis was carried out via ABAQUS explicit code. Hyper-elastic model and the damping factor were introduced to improve an accuracy of the FE analysis. An appropriate FE model was obtained via the comparison of the results of the FE analyses and those of the impact tests. The influence of the impact energy and nose diameter of the impact head on the force-deflection curves, impact time, absorption characteristics of the impact energy, deformation behaviours, and stress-strain distributions was quantitatively examined using the results of FE analysis. The results of the FE analysis showed that the absorption rate of impact energy lies in the range of the 70.7-77.5 %. In addition, it was noted that the absorption rate of impact energy decreases when the impact energy increases and the nose diameter of the impact head decreases. The local deformation of the impacted region was rapidly increased when the impact energy was larger than 76.2 J and the nose diameter was 20 mm. A critical impact energy, which occur the instability of the DP780, was estimated using the relationship between the plastic strain and the impact energy. Finally, characteristics of the plastic energy dissipation and the strain energy density were discussed.

• Asian-Australasian Journal of Animal Sciences
• /
• 제17권1호
• /
• pp.53-62
• /
• 2004

The aim of this study was to predict the energy value and dynamic degradation of roughage in Taiwan using the $Daisy^{(R)}$. in vitro fermentation method to provide information on one of the very important nutrients for ration formulation. The second objective was to study the effects of Aspergillus oryzae (AFE) inclusion on nutrient utilization. Three ruminal fistulated dry dairy cows were used for rumen fluid and fifteen conventional forages used in dairy cattle were collected around this island. The degradability of these feedstuffs with and without AFE ($Amaferm^{(R)}$.) treatment was measured using the $Daisy^{(R)}$. in vitro method. The roughage energy values, including TDN and NEL, were calculated according to Robinson (2000). Results from the 30 h in vitro neutral detergent fiber (NDF) degradability and predicted energy evaluations showed that alfalfa (among the forages) contained the highest degradability and energy values, Bermuda straw having the lowest. Peanut vines and corn silage contained higher energy values and the lowest value found in Pangola and Napier grasses among the locally produced forages. Pangola and Napier grasses had lower values than most imported forages except Bermuda straw. Among the by-products, wheat middling contained the highest NDF degradability, while rice bran contained the richest energy value due to its high oil content. From the dynamic dry matter (DM), organic matter (OM), acid detergent fiber (ADF) and neutral detergent fiber (NDF) degradation, corn silage contained the highest effective degradation among the local forages; wheat middling (among the by-products) degraded the fastest in DM, OM, ADF and NDF and showed the highest effective degradability. AFE inclusion was inconsistent among the forages. Alfalfa hay showed significantly increased 30 h NDF degradability and energy values, Pangola hay, Napier grass and brewer's grains showed decreased degradability and energy values. AFE inclusion increased the DM, OM and NDF degradation rate in most forage, but only increased the DM degradation rate in sorghum distiller's grains, the OM degradation rate in bean curd pomace and the NDF and ADF degradation rates in soy pomace (among the by-products).

• 대한의용생체공학회:의공학회지
• /
• 제26권6호
• /
• pp.357-363
• /
• 2005

Active contour models have been extensively used to segment, match, and track objects of interest in computer vision and image processing applications, particularly to locate object boundaries. With conventional methods an object boundary can be extracted by controlling the internal energy and external energy based on energy minimization. However, this still leaves a number of problems, such as initialization and poor convergence in concave regions. In particular, a contour is unable to enter a concave region based on the stretching and bending characteristic of the internal energy. Therefore, this study proposes a method that controls the internal energy by moving the local perpendicular bisector point of each control point on the contour, and determines the object boundary by minimizing the energy relative to the external energy. Convergence at a concave region can then be effectively implemented as regards the feature of interest using the internal energy, plus several objects can be detected using a multi-detection method based on the initial contour. The proposed method is compared with other conventional methods through objective validation and subjective consideration. As a result, it is anticipated that the proposed method can be efficiently applied to the detection of the pulmonary parenchyma region in medical images.

• 한국태양에너지학회 논문집
• /
• 제40권5호
• /
• pp.13-22
• /
• 2020

Day ahead forecast is necessary for the electricity market to stabilize the electricity penetration. Numerical weather prediction is usually employed to produce the solar irradiance as well as electric power forecast for longer than 12 hours forecast horizon. Korea Meteorological Administration operates the UM-LDAPS model to produce the 36 hours forecast of hourly total irradiance 4 times a day. This study interpolates the hourly total irradiance into 15 minute instantaneous irradiance and then compare them with observed solar irradiance at four ground stations at 1 minute resolution. Numerical weather prediction model employed here was produced at 00 UTC or 18 UTC from January to December, 2018. To compare the statistical model for the forecast horizon less than 3 hours, smart persistent model is used as a reference model. Relative root mean square error of 15 minute instantaneous irradiance are averaged over all ground stations as being 18.4% and 19.6% initialized at 18 and 00 UTC, respectively. Numerical weather prediction is better than smart persistent model at 1 hour after simulation began.

• 국제초고층학회논문집
• /
• 제8권2호
• /
• pp.101-106
• /
• 2019

Assessing the energy performance of supertall buildings often does not consider variations in energy consumption due to the change of environmental conditions such as temperature, pressure, and wind speed associated with differing elevations. Some modelers account for these changing conditions by using a conventional temperature lapse rate, but not many studies confirm to the appropriateness of applying it to tall buildings. This paper presents and discusses simulated annual energy consumption results from a 600 m tall skyscraper floor plate located in Dubai, UAE, assessed using ground level weather data, a conventional temperature lapse rate of $6.5^{\circ}C/km$, and more accurate simulated 600 m weather data. A typical office floorplate, with ASHRAE 90.1-2010 standards and systems applied, was evaluated using the EnergyPlus engine through the OpenStudio graphical user interface. The results presented in this paper indicate that by using ground level weather data, energy consumption at the top of the building can be overestimated by upwards of 4%. Furthermore, by only using a lapse rate, heating energy is overestimated by up to 96% due to local weather phenomenon such as temperature inversion, which can only be conveyed using simulated weather data. In addition, sizing and energy consumption of fans, which are dependent both on wind and atmospheric pressure, are not accurately captured using a temperature lapse rate. These results show that that it is important, with the ever increasing construction of supertall buildings, to be able to account for variations in climatic conditions along the height of the building. Adequately modeling these conditions using simulated weather data will help designers and engineers correctly size mechanical systems, potentially decreasing overall building energy consumption, and ensuring that these systems are able to provide the necessary indoor conditions to maintain occupant comfort levels.

• Current Photovoltaic Research
• /
• 제9권2호
• /
• pp.59-73
• /
• 2021

The purpose of this study is to develop a business model that efficiently converts diesel power generation systems to renewable energy microgrids (MG) in large-scale islands. Most of the previous studies on the conversion of renewable energy MG in islands had limitations dealing with efficiency from the perspective of suppliers. However, the microgrid has the characteristic of getting benefits through the interaction between the consumer and the supplier. In addition, the efficient MG business model from the perspective of new institutional economics is a structure in which consumers and suppliers jointly participate. Therefore, this study assumed that the MG business model in which the supplier's MG and the consumer's community solar participated would benefit all participants, and verified the assumptions using domestic island data. In terms of supplier investment, the cost of power supply (LCOE) of assumed model was calculated to be 14.0% lower than that of the diesel model and 3.7% lower than that of the supplier-only MG model. From the perspective of consumer investment, electricity bills are expected to be reduced by more than 200,000 won per household per year through self-generation of solar power. Social benefits are expected to reduce external environmental costs. The CO₂ emissions of the assumed model were calculated to be 39.5% lower than the diesel model and 1.5% lower than the supplier-only MG model. Therefore, the MG business model with consumer participation proposed in this study is expected to be an efficient alternative to renewable energy MG conversion in domestic islands, and is meaningful as an energy plan that improves the benefits of local residents.