• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.126-129
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• 2003

자동 음성 인식(ASR) 시스템에, 끝점 추출과 에너지 정규화는 중요한 역할을 하게 된다 그러나 낮은 SNR이나 nonstationary 환경에서, 기존 방법은 끝점 추출과 에너지 정규화에 있어서 자주 실패하게 되며, ASR을 급격히 열화시키곤 한다. ASR을 수행하기 위해, 최적의 필터에 3상태 천이도를 사용하고, 필터는 정확성과 강인함을 확실히 하기 위해 여러 이론들을 이용하여 설계하였고 여러 가지 잡음이 있는 음성 신호환경에서 거의 일정한 응답을 주었다. 검출된 끝점은 곧바로 에너지 정규화에 적용된다. 실험 결과는 제안된 알고리즘이 낮은 SNR에서 에러율을 크게 감소시키고 있다는 것을 보여준다.

• Journal of Powder Materials
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• v.30 no.5
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• pp.436-441
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• 2023

Molybdenum-tungsten (Mo-W) alloy sputtering targets are widely utilized in fields like electronics, nanotechnology, sensors, and as gate electrodes for TFT-LCDs, owing to their superior properties such as high-temperature stability, low thermal expansion coefficient, electrical conductivity, and corrosion resistance. To achieve optimal performance in application, these targets' purity, relative density, and grain size of these targets must becarefully controlled. We utilized nanopowders, prepared via the Pechini method, to obtain uniform and fine powders, then carried out spark plasma sintering (SPS) to densify these powders. Our studies revealed that the sintered compacts made from these nanopowders exhibited outstanding features, such as a high relative density of more than 99%, consistent grain size of 3.43 ㎛, and shape, absence of preferred orientation.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.935-940
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• 2023

Digital-twin technology is emerging as an innovative solution for all industries, including manufacturing and production lines. Therefore, this paper optimizes all the energy used in a biomass plant based on unused resources. We will then implement a digital-twin prototype for biomass plants and evaluate its performance in order to improve the efficiency of plant operations. The proposed digital-twin prototype applies a standard communication platform between the framework and the gateway and is implemented to enable real-time collaboration. and, define the message sequence between the client server and the gateway. Therefore, an interface is implemented to enable communication with the host server. In order to verify the performance of the proposed prototype, we set up a virtual environment to collect data from the server and perform a data collection evaluation. As a result, it was confirmed that the proposed framework can contribute to energy optimization and improvement of operational efficiency when applied to biomass plants.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.803-809
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• 2023

This paper analyzes and evaluates to optimally build a data collection system essential for factory energy management systems on an edge-based lightweight platform. A "Sensor/OPC-UA simulator" was developed based on sensors in an actual food factory and used to evaluate the storage engine of edge devices. The performance of storage engines in edge devices was evaluated to suggest the optimal storage engine. The experimental results show that when using the RocksDB storage engine, it has less than half the memory and database size compared to using InnoDB, and has a 3.01 times faster processing time. This study enables the selection of advantageous storage engines for managing time-series data on devices with limited resources and contributes to further research in this field through the sensor/OPC simulator.

• Journal of Climate Change Research
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• v.8 no.3
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• pp.231-237
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• 2017

In this study, the $N_2O$ emission factor of the facility was developed by measuring the kiln type pyrolysis melting facility. This used PAS (Photoacoustic Spectroscopy) method and measured the $N_2O$ emission concentration. From March 2016 to April 2016, it was measured over a total of two times and $N_2O$ concentrations were measured continuously for 24 hours using a 24 hour continuous measuring instrument (LSE-4405). The measured $N_2O$ emission concentration of the pyrolysis melting facility was 0.263 ppm on average and the emission concentration distribution in the range of 0.013~0.733 ppm was obtained. Therefore, the $N_2O$ emission factor of the kiln-type pyrolysis melting facility was estimated to be $0.829gN_2O/ton$-Waste. As a result of comparing the $N_2O$ emission factor of the thermal kiln type pyrolysis melting facility and the previous study, previous studies were about 18 times higher. It is estimated that this is due to the difference of furnace temperature, oxygen concentration and denitrification facilities. It is considered that the study of the emission factor of pyrolysis melting facility is an important factor in improving the credibility of greenhouse gas inventory in waste incineration sector.

• Journal of the Korean Institute of Gas
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• v.10 no.4 s.33
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• pp.34-40
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• 2006

This paper provides a fusion technology between a district cooling energy system and an environment conservation policy based on the energy savings and reusable cold energy resources. The district heating and cooling systems are very effective ways for an energy saving, a cost reduction and a safety control. It is necessary to equalize the energy savings and an environmental preservation policy for an improved human lift. A gasification process of a liquefied natural gas, cooling water from deep seawater and an ice water thermal storage system may produce a cold energy. A district cooling system is used to cool an apartment, office buildings and factory facilities with a cooling energy supply pipeline. LNG cooling energy will switch a conventional air-conditioning system, which is operated by on electrical energy and a Freon refrigerant. Coincident with significant clean energy and operating cost savings, LNG cold energy system owen radical reductions in an air-borne pollutant, $CO_2$ and the release of environmentally harmful refrigerants compared with that of the conventional air-conditioning system. This study provides useful information on the fusion technology of a LNG cold energy usage and energy savings, and environmental conservation.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.817-823
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• 2023

Manufacturing plants face the challenge of reducing energy use in response to climate change. Reducing energy consumption can be seen as one of the most important issues, such as reducing production costs and improving efficiency. Among manufacturing industries, the increase in energy consumption in the food industry is gradually increasing along with the improvement of the standard of living and the increase in population. In order to save energy in food processing plants, it is important to identify and analyze energy consumption characteristics in energy-consuming processes. Prior to this, it is necessary to monitor and analyze existing energy consumption to derive reduction measures. In this study, a small and medium-sized food processing plant producing processed meat products was used as a case study to identify and analyze the energy consumption structure at typical cycle/stage level of the batch heating process. From this, we tried to establish realistic and quantitative goals that can be obtained under individual process operating conditions. The results of this study will be used as basic data for the development of diffusion and pervasive energy saving FEMS technology for common core processes of food factories of small and medium-sized enterprises in the future.

• Journal of Soil and Groundwater Environment
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• v.27 no.6
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• pp.37-46
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• 2022

As the amount of livestock wastewater increases, ammonia contamination in surface water and groundwater is also increasing, and its treatment is urgently needed. In this study, indigenous soil bacteria was utilized for ammonia removal in artificial wastewater and associated removal mechanisms and efficiencies were evaluated. Two batch reactors were configurated to contain natural soil and artificial wastewater at 1:10 mass ratio, and incubated for 84 and 168 hours, respectively. The results showed that ammonia was completely removed within 48 and 72 hours in the first and second reactors, respectively. There were no significant changes in ammonia concentrations in the control groups without soil. Nitrate was formed in the reactors, indicating that the main removal mechanism of ammonia was nitrification by nitrifying bacteria. Nitrate was further converted to nitrogen gas by denitrification in the anaerobic environment, which was caused by consumption of oxygen during the nitrification process.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.496-504
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• 2023

Countries worldwide are striving to find new sources of sustainable energy without carbon emission due to the increasing impact of global warming. With the advancement of the fourth industrial revolution on a global scale, there has been a substantial rise in energy demand. Simultaneously, there is a growing emphasis on utilizing energy sources with minimal or zero carbon content to ensure a stable power supply while reducing greenhouse gas emissions. In this comprehensive overview, a comparative analysis of carbon reduction policies of government was conducted. Based on international carbon neutrality scenarios and the presence of remaining thermal power generation, it can be categorized into two types: "Rapid" and "Safety". For the domestic scenario, the projected power demand and current greenhouse gas emissions in alignment with "The 10th Basic Plan for Electricity Supply and Demand" was examined. Considering all these factors, an overview of the current status of carbon neutrality technologies by focusing on the energy sector, encompassing transitions, hydrogen, transportation and carbon capture, utilization, and storage (CCUS) was offered followed by summarization of key technological trends and government-driven policies. Furthermore, the central aspects of the domestic carbon reduction strategy were proposed by taking account of current mega trends in the energy sector which are highlighted in international scenario analyses.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.3
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• pp.247-254
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• 2022

Slush hydrogen containing liquid and solid hydrogen is expected to achieve zero boil-off by suppressing boil-off gas because heat of fusion for solid absorbe the heat ingress from atmosphere. In this paper, quantitative analysis on storage cost considering specific energy consumption between 1,000 m³ class liquid hydrogen storage system with re-liquefaction and slush hydrogen storage system during equivalent zero boil off period. Even though approximately 50% of total storage capacity should be converted into solid phase during the initial cargo bunkering, total energy consumption to convert into slush hydrogen is relatively 25% less than re-liquefaction energy for boil off hydrogen during zero boil off period. That's because energy consumption of slush phase change take up only 1.8% of liquefaction energy. moreover, annual revenue requirement including CAPEX, OPEX and electric cost for slush hydrogen storage could be more reduced approximately 32.5% than those of liquid hydrogen storage and specific energy storage cost ($/kg-H₂) could also be lowered by about 41.7% compared with liquid hydrogen storage.