• 한국농림기상학회지
• /
• 제21권4호
• /
• pp.347-357
• /
• 2019

GIS 기반의 농업 기후 자료의 처리 및 분석 체계의 유용성은 클라우드, 온프레미스, 하이브리드 구조와 같은 컴퓨팅 인프라의 신뢰성, 가용성에 영향을 받는다. 현재는 정보 기술 산업에서 클라우드 컴퓨팅의 시대라고 할 수 있을 만큼 클라우드와 관련된 기술이 확산되어 있으나, 장기간의 운영 경험으로 누적된 다양한 참조 사례를 볼 때 온프레미스 기술이 클라우드 기술 보다 유리한 경우도 있다. 또한 클라우드 환경의 경우 초기 비용이 온프레미스와 비교하여 저렴하지만 사용 방법에 따라 매우 높은 비용이 부과될 가능성이 있다. 따라서 각 시스템의 특성에 맞는 적절한 구성법이 고려될 필요가 있다. 본 연구에서는 농업 기후 자료 처리 및 분석 체계에 이용가능한 일반적인 컴퓨팅 플랫폼 4개를 소개하고 대량의 자료 처리 및 저장의 특성을 갖는 응용 시스템을 적용하여 각 플랫폼의 장단점을 비교 분석하였다. 현재로서는 대량의 농업 기상 및 기후 데이터를 필요로 하는 시스템은 비용상의 이유로 퍼블릭 클라우드로의 이주가 불가능함을 확인하였다. 향후 참조될 가능성이 높지 않은 대용량 자료를 클라우드 상에 유지해야 하는 점이 주요 원인이다. 따라서 가장 높은 비용의 저장 및 백업 부분을 클라우드 대신 온프레미스에서 운용하고, 자료의 분석 및 처리 그리고 표출 부분과 같이 유연성이 요구되는 부분은 클라우드에서 운용하는 것이 합리적이다.

• IEIE Transactions on Smart Processing and Computing
• /
• 제6권1호
• /
• pp.1-9
• /
• 2017

This paper proposes to improve the performance of a strap down inertial navigation system using a foot-mounted low-cost inertial measurement unit/magnetometer by configuring an attitude and heading reference system. To track position accurately and for attitude estimations, considering different dynamic constraints, magnetic measurement and a zero velocity update technique is used. A conventional strap down method based on integrating angular rate to determine attitude will inevitably induce long-term drift, while magnetometers are subject to short-term orientation errors. To eliminate this accumulative error, and thus, use the navigation system for a long-duration mission, a hybrid configuration by integrating a miniature micro electromechanical system (MEMS)-based attitude and heading detector with the conventional navigation system is proposed in this paper. The attitude and heading detector is composed of three-axis MEMS accelerometers and three-axis MEMS magnetometers. With an absolute algorithm based on gravity and Earth's magnetic field, rather than an integral algorithm, the attitude detector can obtain an absolute attitude and heading estimation without drift errors, so it can be used to adjust the attitude and orientation of the strap down system. Finally, we verify (by both formula analysis and from test results) that the accumulative errors are effectively eliminated via this hybrid scheme.

• 한국시스템다이내믹스연구
• /
• 제13권4호
• /
• pp.33-55
• /
• 2012

The research is to identify important diffusion factors and their effects on green car diffusion process using system dynamics perspectives and a causal-loop analysis. Through a deep review on previous research, we have found the important factors of green car diffusion process. Price, driving range, network effect, recharge system, fuel cost had important facilitation on consumer attraction and green car diffusion. Based on the review, we have constructed a causal loop diagram explaining hybrid car diffusion process. We have found 3 important reinforcing loops in the causal loop diagram. Loop for learning & economies of scale(supply side), loop for network effect(consumer side), and loop for battery development(technology side) had most significant roles in the whole diffusion process. Through a deliberate analysis on the 3 causal loops, we have found meaningful results. First, there seems to exist a critical mass in the diffusion. Second, of the 3 loops, the battery technology had most significant role. Third, not consumer installed base but sales must be a standard to decide whether the critical mass is achieved or not. Based on these findings, several meaningful implications are suggested for the government and corporations related to the green car industries.

• 한국유체기계학회 논문집
• /
• 제15권4호
• /
• pp.50-54
• /
• 2012

Wind-power generation, which is recently drawing attention as one of renewable energies across the world, has been developed mainly by Europe. As the demand for the wind-power generation rose and the amount of wind-power generation increased, the studies on megawatt-class wind-power system have been active, and the use of composite with such properties as less weight, more strength, anti-corrosion and environment-friendliness has required gradually. In other word, wind turbine tower will be required to be lighter, more reliable and more consistent. Therefore it is necessary to lose weight of the wind turbine tower. This points squarely toward hybrid/composite tower production growing. It is important to note however that hybrid/composite tower production as it is today is flawed and that there are ways to improve greatly on the performance of these towers in manufacturing process and in their in-service performance. Through this, we have some detail on the current process and its advantage of cost and weight of towers.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.251.2-251.2
• /
• 2013

Natural photosynthesis utilizes two proteins, photosystem I and photosystem II, to efficiently oxidize water and reduce NADP+ to NADPH. Artificial photosynthesis which mimics this process achieve water splitting through a two-step Z-schematic water splitting process using man-made synthetic materials for hydrogen fuel production. In this study, Z-scheme system was achieved from the hybrid materials which composed of hydrogen production part as photosystem I protein and water oxidizing part as semiconductor BiVO4. Utilizing photosystem I as the hydrogen evolving part overcomes the problems of existing hydrogen evolving p-type semiconductors such as water instability, expensive cost, few available choices and poor red light (>600 nm) absorbance. Some problems of photosystem II, oxygen evolving part of natural photosynthesis, such as demanding isolation process and D1 photo-damage can also be solved by utilizing BiVO4 as the oxygen evolving part. Preceding research has not suggested any protein-inorganic-hybrid Z-scheme composed of both materials from natural photosynthesis and artificial photosynthesis. In this study, to realize this Z-schematic electron transfer, diffusion step of electron carrier, which usually degrades natural photosynthesis efficiency, was eliminated. Instead, BiVO4 and Pt-photosystem I were all linked together by the mediator gold. Synthesized all-solid-state hybrid materials show enhanced hydrogen evolution ability directly from water when illuminated with visible light.

• 한국기계가공학회지
• /
• 제20권3호
• /
• pp.53-59
• /
• 2021

In vibration-free vehicles such as limousine buses, the vibration is minimized by installing an air spring instead of the leaf spring used in the existing freight cars to prevent the damage to the loaded cargo from shocks generated during movement. In the existing vehicles, steel structures support the air spring system. This study was aimed at replacing the steel structures used in the Z-spring by carbon fiber and glass fiber reinforced plastics. In addition, the mechanical properties (elastic modulus, tensile strength, and shear strength) of carbon fiber and glass fiber prepreg were derived using specimens molded with the corresponding prepreg. The final goal was to develop a material lighter than the conventional steel material but with enhanced mechanical properties. Although the CF prepreg exhibited excellent mechanical properties, the production cost was extremely high. To overcome this limitation, hybrid composites with GF prepreg were examined, which are expected to be promising future materials.

• 한국수자원학회논문집
• /
• 제54권7호
• /
• pp.475-484
• /
• 2021

상수관망의 최적설계는 절점의 최소 요구 수압을 만족함뿐만 아니라 관로비용의 최소화 등을 목적으로 한다. 상수관망 설계안의 수는 다양한 관의 배치로 인해 기하급수적으로 증가한다. 상수관망 설계에서 최적화된 설계를 제안하기 위해 다양한 최적화 알고리즘들이 적용되었다. 본 연구에서는 상수관망 최적설계에 자가적응형 매개변수를 개선한 Modified Hybrid Vision Correction Algorithm (MHVCA)을 적용하였다. 기존 Hybrid Vision Correction Algorithm (HVCA)의 Hybrid Rate (HR)를 비선형적 HR로 수정하여 성능을 개선하였다. 제안된 MHVCA의 성능을 확인하기 위해 결정변수가 2개 및 30개로 구성된 수학문제와 제약조건이 있는 수학문제에 적용하였다. MHVCA의 적용결과를 검토하기 위해 Harmony Search (HS), Improved Harmony Search (IHS), Vision Correction Algorithm (VCA) 및 HVCA와 비교하였다. 최종적으로 MHVCA를 상수관망 최적설계 문제에 적용하여 결과를 다른 알고리즘들과 비교하였다. 수학문제 및 상수관망 설계 문제에서 MHVCA가 다른 알고리즘들에 비해 좋은 결과를 보여주었다. MHVCA는 본 연구에서 적용한 문제뿐만 아니라 다양한 수자원공학 문제에 적용하여 좋은 결과를 보여줄 수 있을 것이다.

• 동력기계공학회지
• /
• 제22권1호
• /
• pp.41-47
• /
• 2018

This paper analyzes the output characteristics of a self excited induction generator with isolated mode according to change of its speeds and loads for building a hybrid electric propulsion system in special purpose ships by using power take off. The induction generators are being considered as an alternative choice to the well-developed generators because of their lower unit cost, inherent ruggedness, operational and maintenance simplicity. However, the generator working by stand alone has a few problems that the reactive power is required to establish the air gap magnetic flux, and the induced voltage and magnetizing current fluctuate when the load is varied. In spite of its advantages, basic design data of the capacitor bank and behaviors of the output characteristics of the generator are not sufficient for the system. Based on the operating condition(speed range of main engine) of the target boat, a reduced experimental equipment system was constructed to analyze the output characteristics of the SEIG. And a suitable capacitor bank of a stand-alone generator and its output characteristics under various loads was investigated in detail through these experiments. According to the experimental result, it was confirmed that the capacitor bank should be $70{\mu}F{\sim}100{\mu}F$, and the proper SEIG induced voltage should be DC 80 V ~ 250 V in order to storage electrical energy into a battery.

• 한국건축시공학회지
• /
• 제12권5호
• /
• pp.518-527
• /
• 2012

This study uses a hybrid estimation tool for effective cost data management of building projects, and develops a realistic cost estimation model. The method makes use of newly available information as the project progresses, and project cost and percentage progress are analyzed and used as inputs for the developed system. For model development, case-based reasoning (CBR) is proposed, as it enables complex nonlinear mapping. This study also investigates analytic hierarchy process (AHP) for weight generation and applies them to a real project case. Real case studies are used to demonstrate and validate the benefits of the proposed approach. By using this method, an evaluation of actual project performance can be developed that appropriately considers the natural variability of construction costs.

• Environmental Engineering Research
• /
• 제23권1호
• /
• pp.114-119
• /
• 2018

Yarn dyed wastewater has to be treated prior to disposal into the water bodies due to its high content of harmful organic compounds. In this study, the performance of Chemical Oxygen Demand (COD) removal and kinetic rate constant are investigated via hybrid electrocoagulation-Fenton in a continuous system using wastewater discharged from a yarn dyed industry in Surabaya city. The wastewater was treated in a batch mode using electrocoagulation to reduce Total Suspended Solid, followed by Fenton method in a continuous system to reduce COD level. Various Fe(II) feeding modes, molar ratio of $Fe(II)/H_2O_2$, initial pH of wastewater, and flow rate are used in this study. The results show that COD removal process obeys a pseudo-first order kinetics. At $Fe(II)/H_2O_2$ ratio of 1:10, initial wastewater pH of 3.0, and feed flow rate of 30 mL/min, the COD removal efficiency was observed to be 80%, and the kinetic rate constant is $0.07046min^{-1}$. The chemical cost for the treatment estimated to be IDR 160 per L wastewater, which is cheaper than the previously reported batch system of IDR 256/L.