• Journal of the Korean Institute of Gas
• /
• v.15 no.2
• /
• pp.63-68
• /
• 2011

As an effective utilization of biomass, organic wastes and coal, attention has been made to use syngas to a reciprocating engine to generate power. However, significant component variation of syngas depending upon origin and gasification conditions, and its lower heating value than that of LPG and CNG can create difficulties in stable engine operation. Thus it is necessary to address these issues in order to successfully develop power generation engines. As a primary step to resolve these problems, effects of H2 content variation in syngas on engine performance and emission characteristics were discussed in this study. The results show that as H2 % in syngas increases, more stable combustion was achieved with retarded MBT spark timing and engine efficiency becomes maximum with syngas of 10% H2. In addition, NOx emission increased while THC emission decreased as H2 % rises in the syngas.

• Korean Chemical Engineering Research
• /
• v.50 no.3
• /
• pp.479-491
• /
• 2012

In this paper we performed evaluation of the economics of a district heating system (DHS) consisting of energy suppliers and consumers, heat generation and storage facilities and power transmission lines in the capital region, as well as identification of optimal operating conditions. The optimization problem is formulated as a mixed integer linear programming (MILP) problem where the objective is to minimize the overall operating cost of DHS while satisfying heat demand during 1 week and operating limits on DHS facilities. This paper also propose a new forecasting model of the system marginal price (SMP) using past data on power supply and demand as well as past cost data. In the optimization, both the forecasted SMP and actual SMP are used and the results are analyzed. The salient feature of the proposed approach is that it exhibits excellent predicting performance to give improved energy efficiency in the integrated DHS.

• Journal of Korea Society of Industrial Information Systems
• /
• v.10 no.2
• /
• pp.76-81
• /
• 2005

This research approached electrical characteristics of organic light emitting diodes getting into the spotlight by next generation display device. Basic mechanism of OLED's emitting is known as that electron by cathode of lower work function and hole by anode of higher work function are driven and recombine exciton-state being flowed in emitting material layer passing carrier transport layer In order to make many electron-hole pairs, we must manufacture device in multi-layer structure. There are Carrier Injection Layer(CIL), Carrier Transport Layer(CTL) and Emitting Material Layer(EML) in multi-layer structure. It is important that regulate thickness of layer for high luminescence efficiency and set mobility of hole and electron.

• Journal of the Korean Institute of Gas
• /
• v.4 no.3 s.11
• /
• pp.26-32
• /
• 2000

Because of the continuous growth of energy consumption, and also the tendency to site power lines and pipelines along the same routes, the close proximity of high voltage structures and metallic pipelines has become more and more frequent. Moreover, normal steady state and fault currents become higher as electric networks increase in size and power Therefore, there has been and still is a growing concern(safety of people marking contact with pipeline, risk of damage to the pipeline coating, the metal and equipment connected to pipeline, especially cathodic protection system) about possible hazards resulting from the influence of high voltage power system on metallic structures(gas pipeline, oil pipeline and water pipeline etc.). Therefore, we analyze the interference problems when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about interference mechanism, AC corrosion limitation of safety voltage and analysis of induction voltage.

• Journal of Sensor Science and Technology
• /
• v.6 no.4
• /
• pp.290-297
• /
• 1997

In this study, the radiation monitoring system using CsI(TI) scintillation counter is developed for the measurement of radiation distribution in the field of high dose level. When the inner diameter of collimator is 8 mm, we have realized the optimum detecting efficiency and spatial resolution. At that time, the position resolution was 10 cm at 1 m from the system. And experimental results indicated that the energy resolution of the system were 10 % for 662 keV of Cs-137, 7.6 % for 1.17 MeV of Co-60, and 5.8 % for 1.33 MeV of Co-60. Also, we have shown that the real radiation distribution images may be obtained by our measurement system.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.209.1-209.1
• /
• 2013

GaP는 가시광선 발광다이오드을 얻을 수 있는 적절한 재료중의 하나로 해당영역의 파장에 대하여 높은 양자효율을 얻을 수 있고, 깊은 준위 재결합이 없기 때문에 GaP 녹색 및 As 첨가한 GaAsP 적색 LED 에 적용할 수 있습니다. 또한, 상온에서 2.2 eV 에 해당하는 넓은 에너지 밴드갭을 가지고 있으므로, 소음이 없는 자외선 검출기에도 적합합니다. 이 물질에 대한 소자들은 기존에 GaP 기판을 사용하였습니다. 최근, GaP 와 격자상수가 비슷한 Si 기판을 활용하여 그 위에 성장하는 방법에 대한 관심이 많아졌습니다. Si는 물리적 및 화학적으로 안정하고 딱딱한 소재이며 대면적 기판을 쉽게 얻을 수 있어 전자 기기 및 대규모 집적 회로의 좋은 소재입니다. Si 와 대조적으로 GaP은 깨지기 쉬운 재료이며 GaP 기판은 Si와 같은 대면적 기판을 얻을 수 없습니다. 이러한 문제의 한 가지 해결책은 Si 기판위에 GaP 층의 성장입니다. GaP 과 Si의 조합은 현재의 광전소자 들에 더하여 더 많은 응용프로그램들을 가능하게 할 것입니다. 그러나, Si 기판위에 GaP 성장 시 삼차원적 성장 및 역위상 경계면과 같은 문제점들이 발생하므로 질이 높고 균일한 결정의 GaP 를 얻기가 어렵습니다. 따라서, Si 에 GaP 의 성장시 초기 단계를 제어하는 성장 기술이 필요합니다. 본 연구에서는, 유기금속화학증착법을 이용하여 Si 기판위에 양질의 GaP를 얻을 수 있는 최적의 성장조건을 얻고자 합니다. 실험 조건은 Si에 GaP의 에피택셜 성장의 초기 단계에 영향을 주는 V/III 비율, 성장압력, 기판방향 등을 가변하는 조건으로 진행하였습니다. V/III 비율은 100~6400, 성장 압력은 76~380 Torr로 진행하였고, Si 기판은 just(001)과 2~6도 기울어진 (001) 기판을 사용하였습니다.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.4
• /
• pp.538-549
• /
• 2021

In this study, a trim tab on the stern hull of a small high-speed vessel of approximately 10 m length sailing at a Froude number of 1.0 was designed for energy efficiency. The running attitude and resistance performance of the bare hull and trim tab hull at several angles to the base line were analyzed for model and full scale ships using computational fluid dynamics, and compared to investigate the scale effect. The analysis results for the bare hull were quite similar, but a difference in the attitude control under same conditions of the trim tab was observed, resulting in the total resistance error. However, there was no significant difference in tendency of the variation in the resistance with the attitude. Thus, the optimum running attitude could be determined from the tendency despite the scale effect, but a full scale analysis is required to analyze the control of the attitude by the trim tab and flow characteristics near the full scale ship.

• Journal of IKEEE
• /
• v.26 no.4
• /
• pp.537-544
• /
• 2022

This paper analyzes the occurrence and cause of bond wires fusing used in the manufacture of pulsed high power amplifiers. Recently GaN HEMT has been spotlight in the fields of electronic warfare, radar, base station and satellite communication. In order to produce the maximum output power, which is the main performance of the high-power amplifier, optimal impedance matching is required. And the material, diameter and number of bond wires must be determined in consideration of not only the rated current but also the heat generated by the transient current. In particular, it was confirmed that compound semiconductor with a wide energy band gap such as GaN trigger fusing of the bond wire due to an increase in thermal resistance when the design efficiency is low or the heat dissipation is insufficient. This data has been simulated for exothermic conditions, and it is expected to be used as a reference for applications using GaN devices as verified through IR microscope.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.19 no.1
• /
• pp.109-117
• /
• 2017

In the production of organic Panax ginseng, the morphological changes were confirmed by providing general water and microbubble water, respectively. Analysis of seedling ginseng treated with general water and bubbles water revealed that many seedlings were formed in the seedling treated with bubble water, and about 15% weight increase occurred in the growing period. The growth rate of stem, leaf, and root was about 15% higher than that of all. Taken together, the growth of seedling cultivation using bubble water was about 15% overall. In order to process ginseng, the dried ginseng was higher in dry weight than the general water seedling seedlings grown in bubble water. This suggests that more processed products will be produced per unit weight at the time of producing the processed products at the farm, which can directly increase the farm income.

• The Transactions of the Korea Information Processing Society
• /
• v.13 no.2
• /
• pp.1-12
• /
• 2024

Modern cities are actively adopting smart city services to address various urban challenges. Geospatial information acts as the foundational infrastructure of smart cities, promoting the sustainable development of urban areas. Consequently, as the standardization and utilization of geospatial information increase, the efficiency and sustainability of smart city operations improve. To achieve this, collaboration among diverse stakeholders is crucial for delivering optimal smart city services based on geospatial information. This paper defines smart city services, focusing on transportation and building-energy domains, based on the life cycle of geospatial information technology. Emphasis is placed on the importance of applying and utilizing geospatial information standards. Additionally, this paper proposes the Smart City based on Geospatial Information standards (SCGI) framework to provide insights into standardizing smart city services mapped to geospatial information standards. This research suggests a new paradigm for standardizing smart city services using geospatial information standards to offer customized solutions, thereby discussing the future development possibilities of smart cities.