• Plant Journal
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• v.17 no.2
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• pp.32-41
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• 2021

Recently, air environmental issues such as fine dust have rapidly emerged as national issues, and intensive environmental regulations are being applied to coal-fired power plants. This study introduces the case of improving the performance of desulfurization facilities for removing sulfur oxides and dust, which are the main air pollutant emitters of coal-fired power plants, and conducted four case studies to improve the performance of 1,000 MW power plants currently in operation and carried out construction. Liquid ratio was increased by remodeling the absorption tower of desulfurization facilities, and vaporization reaction was promoted by increasing the flow rate of oxidized air. In addition, the gas heater leakage rate was improved to improve the efficiency of final desulfurization facilities. It is expected that performance improvement work considering harmony with existing facilities will satisfy the regulations(25ppm of sulfur oxides, 5mg/Sm³) that will be applied from 2023, and can be referred to other thermal power plants for review and application.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.6
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• pp.357-365
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• 2022

Refrigerant mischarging is one of the most frequently occurring failure modes in air conditioners, and both undercharging and overcharging degrade cooling performance. Therefore, it is important to accurately determine the amount of charged refrigerant. In this study, a support vector machine (SVM) model was developed to multi-classify the refrigerant mischarge through steady-state identification via fuzzy clustering techniques. For steady-state identification, a fuzzy clustering algorithm was applied to the air conditioner operation data using the difference between moving averages. The identification results using the proposed method were compared with those using existing steady-state determination techniques studied through the inversed Fisher's discriminant ratio (IFDR). Subsequently, the main features were selected using minimum redundancy maximum relevance (mRMR) considering the correlation among candidate features, and an SVM multi-classification model was devised using the derived features. The proposed method achieves satisfactory accuracy and robustness from test data collected in the new domain.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.153-160
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• 2012

Various social problems such as traffic congestion, car accidents and environmental problems(air pollution, noises etc.) have been happening in the Seoul metropolitan area that has the car oriented traffic system providing cars continuously. Along with this, the financial burden caused by current oil price anxiety made paradigm shift from caroriented to public transportation-oriented. Its typical example is an arterial branch bus system changing(bus lane through the center of main road) started in Seoul in July, 2004. But study on safety analysis of bus lane and characteristic of accidents are not sufficient enough to now. The bus lanes are expanded to provide roads for better traffic operation and accidents between buses and pedestrians or ordinary vehicles are considered main problems. This study divided each bus route of median bus lane(bus-only lane through the center of main roads) and bus lane at roadside by intersection and collected and analysed data about influence variables of bus accidents chosen in each section. We constructed a logistic model using collected data. As a result, bus lane at roadside are used by both buses and other kinds of vehicles differently from median bus lane and showed such characteristic in accident influence. Therefore access management to factors causing conflict and improvement of operation management are required. In case of median bus lane, the more buses moving general vehicle lane and traffic volume of section were, the more accidents happened. In case that stop line of center lane is not backward, view blocking of vehicles turning left caused accidents.

• Journal of Energy Engineering
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• v.11 no.2
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• pp.90-98
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• 2002

The effects of swirl and combustion parameters on the performance and emission in a turbo-charged D.I. diesel engine of the displacement 9.4L were studied experimentally in this paper. Generally the swirl in the combustion process of diesel engine promotes mixing of the injection fuel and the intake air. It is a major factor to improve the engine performance because the fuel consumption and NO$_{x}$ is trade-off according to the high temperature and high pressure of combustion gas in a turbocharged D.I. diesel engine, it's necessary to thinking over the intake and exhaust system, the design of combustion bowl and so on. In order to choose a turbocharger of appropriate capacity. As a result of steady flow test, when the swirl ratio is increased, the mean flow coefficient is decreased, whereas the gulf factor is increased. Also, through engine test its can be expected to meet performance and emissions by optimizing the main parameter's; the swirl ratio is 2.43, injection timing is BTDC 13$^{\circ}$ CA, compression ratio is 16, combustion bowl is re-entrant 5$^{\circ}$, nozzle hole diameter is $\Phi$0.28*6, turbocharger is GT40 model which are compressor A/R 0.58 and turbine A/R 1.19.

• Journal of Environmental Health Sciences
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• v.24 no.2
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• pp.1-8
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• 1998

This study was carried out to investigate the distribution of PAHs in atmosphere and soil, and their relationship, accumulation tendency in soil, and its contain burden ratio (%) the PM$_{10}$ and soil were sampled adjacent to a roadside and analysed by HPLC from August 25th 1996 to September 22nd 1996 in Seoul and Kunggido area. The main results are summarized below 1. The concentration of PM$_{10}$ in the ambient air was showed in order of industrial region ($142.70\pm 21.77 \mu g/m^3$), commercial region ($136.51\pm 31.62 \mu g/m^3$), residential region ($110.12\pm 14.98 \mu g/m^3$), greenbelt region ($77.44\pm 12.12 \mu g/m^3$), respectively. 2. Distribution of PAHs concentration level in PM$_{10}$ and soil was showed in order of industrial region, commercial region, residential region, greenbelt region, respectively in all components. 3. The contain burden ratio (%) in PM$_{10}$ was attested that BbF was the highest contain burden component (21.7-32%) and An was the lowest contain burden component (0.35-1.95%) in all region. 4. The contain burden ratio (%) in soil was attested that Pb (20.5%) was the highest and An (0.8%) was the lowest contain burden component in industrial region and BbF (21.9%) and An (0.45%) were the same tendency in commercial region and Py (21.6%) and BkF (3.5%) were in residential region, Py (29%) and An (2.6%) were in greenbelt region. 5. The relationship between concentration of PAHs in PM$_{10}$ and soil was attested that the component of BbF (r=0.514) was very highly correlated, and there were significant in Fl and BaA in soil between industrial region and commercial region (P<0.05).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.12
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• pp.1004-1012
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• 2014

In this study, blowoff was investigated in a ducted combustor with the bluff body when acoustic excitation was forced. To observe the flame structure, OH radical chemiluminescence was used and the image was analyzed by using POD (Proper Orthogonal Decomposition) algorithm. Natural gas mainly composed of methane was used as fuel. Blowoff occurred when the equivalence ratio was reduced. Equivalence ratio causing blowoff was measured by changing air flow rate, excitation frequency and sound pressure. Blowoff equivalence ratio was varied depending on the experimental conditions. Vortex frequency behind the bluff body and resonance effect in combustor are the main factors that affect the blowoff equivalence ratios with the excitation.

• Korean Journal of Plant Resources
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• v.20 no.4
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• pp.309-311
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• 2007

This study was conducted to select the most suitable fertilizer level on nursery of mat rush for good quality and high yield. $N-P_{2}O_{5}-K_{2}O=60-30-60$ (kg/10a), fertilizer level on nursery of mat rush showed relatively superior values for all yield components and quality with 57g in fresh weight, 12g in dry weight, 23% in air drying ratio for per plant at the nursery and 125cm in stem length, 150 numbers in stem number, 4,082kg/10a in fresh stem yield, 345kg/10a in long stem yield, 996kg/10a in medium stem yield, 1,421kg/l0a in total stem yield, 34% in dry stem ratio and 30% in long stem ratio at the main paddy field. The results indicate that fertilizer level, $N-P_{2}O_{5}-K_{2}O=60-30-60kg/10a$ in nursery shows different adaptabilities to a particular fertilizer level and 60-30-60 (kg/10a) seems to be the most suitable fertilizer level of mat rush for good quality and high yield.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.688-694
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• 2018

The mixture ratio of two-component liquid silicone is important for the inherent physical characteristics of the finished product. Therefore, it is necessary to uniformly control the ratio of the main material and the sub-material. In this paper, a mixing-ratio control system was designed, which consists of a digital flow meter and a flow control system to measure the flow rate of the raw materials and a pumping system to maintain constant pressure and transfer of the raw materials. In addition, a program was developed to control the organic interlocking and mixing ratio. For the verification of the developed system, we compared the actual weight of raw material with the value measured by the flow meter during pumping, and we measured the physical properties of the mixed material by making test samples with and without the application of the mixing-ratio improvement algorithm. The measured value was close to the reference value with a hardness range of 46-47 and tensile strength of 9.3-9.5 MPa. These results show that the mixing ratio of the liquid silicone is controlled within an error range of ${\pm}0.5%$.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.9
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• pp.1278-1284
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• 2000

An experiment was performed to evaluate different methods for preserving shrimp by-products and to determine their chemical composition. In the first experiment three ratios of shrimp by-product (SBP) to molasses (6:1, 4:1 and 3:1, wet weight), and to cassava root meal (3:1, 2:1 and 1:1, wet weight of shrimp by-product and air-dry weight of cassava root meal) were investigated. The pH of the SBP ensiled with molasses at a ratio of 3:1, and with cassava root meal at a ratio of 1:1, decreased during the first week to below 4.5 and remained low up to day 56 of ensiling, whereas the pH of the mixtures with higher ratios of SBP remained above 7.0, and the material deteriorated rapidly. The dry matter decreased initially in all treatments but then increased slightly from day 28 in the treatment where shrimp by-product was ensiled with cassava root meal at a ratio of 1:1. The crude protein (CP) and ammonia-N $(NH_3-N)$ contents of the preserved shrimp by-product material ensiled with molasses at a ratio of 3:1 increased significantly one week after ensiling. The CP content then remained constant, while the $NH_3-N$ concentration continued to increase up to 56 days after ensiling. When SBP was ensiled with cassava root meal at a ratio of 1:1 the CP content of the silage increased significantly up to 21 days after ensiling and then decreased back to the original level after 56 days, whereas $NH_3-N$ increased markedly up to 14 days and then remained fairly constant up to 56 days. However, the $NH_3-N$ content was significantly higher when SBP was ensiled with cassava root meal than with molasses. A balance experiment was carried out, arranged as a double Latin-square and including 6 F1 (Large White ${\times}$ Mong Cai) castrates fed randomly one of three diets based on cassava root meal, rice bran, and fish meal (FM) or shrimp by-product ensiled with molasses (SBEMO) or with cassava root meal (SBECA) as the main protein source. Apparent organic matter and CP digestibilities were significantly (p<0.001) higher for the fish meal diet than for the two shrimp by-product diets, although CP digestibility in SBEMO and SBECA was similar (p>0.05). N-retention was significantly higher for the fish meal diet than for the SBEMO diet, which in turn was significantly higher than for the SBECA diet (p<0.01). It can be concluded that shrimp by-product can be preserved by ensiling with molasses at a ratio of 3:1 or with cassava root meal at a ratio of 1:1. Nutrient digestibility and N-retention of diets based on these shrimp by-product silages were lower than for similar diets based on fish meal, probably due to their high chitin content and inferior amino acid balance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8386-8393
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• 2015

This study is to investigate the needs for the cool motorcycle helmet and the factors affecting the purchasing intention of cool helmet. The convenient sampling from motorcycle clubs were conducted during 5/20/2014~5/28/2014 on Google DAX. As a result, 197 participants were surveyed. The main reasons of sensing unpleasant feeling wearing helmet were identified as 'hot and uncomfortable feeling' and 'it ruins hair style'. The mean score expressed in terms of five point scale showed that the needs for cool helmet was 3.9 and the purchasing intention of cool helmet was 3.6, respectively. The significant factors influencing the purchasing intention of cool helmet were identified as 'the needs for cool helmet' (odds ratio=6.52) and 'extra paying intention for cool helmet' (odds ratio=1.77). The main reasons of sensing unpleasant feeling wearing helmet were similar to the previous research. However, we can expect that the initial target market for cool helmet would be the low end (less than \40,000 of extra paying intention) or the high end (more than \100,000 of extra paying intention). The main contribution of this study is dealing with the topics related to the purchasing intention of the cool helmet.