• 한국소음진동공학회논문집
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• 제17권9호
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• pp.826-834
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• 2007

A 7K60MC-S low speed diesel engine in a power plant has frequently experienced high vibration since the unit completed construction works. Up to date, no fundamental vibration solutions were reached. Hence, several vibration tests and analyses were conducted to identify the root cause of this high vibration and to suggest the optimal countermeasures for diesel engine. The 9.25 Hz and 25.4 Hz vibrations have been observed on main body during operation. The magnitude of engine upper structural vibration is generally similar in horizontal transverse direction. However, differences in the 'Fore' and 'After' vibration magnitude with the same vibration phase angle at 9.25 Hz occur due to the explosion pulsations of 7 cylinders and the Inertia momentum added by the SCR (selective catalytic reduction) duct system. It was analyzed that the excess structural vibration occurred when the natural frequency of engine body is affected by the exciting sources due to the explosion pressure and the discharge pulsation of the seven cylinders in resonance range.

• KIEAE Journal
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• 제4권2호
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• pp.49-56
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• 2004

This study intends to propose the fundamentals of 'Ecovillage' design by researching into the cycle system of material of 'Crystalwaters' which is having been in charge of a leading role of GEN since 1996 (GEN was formed in 1996) as Ecovillage in Australia. First, to secure the water resources, we can store up rain and the water of valley, and dam. Second, we are able to use the natural filter apparatus, do tree-planting of roof to gain better quality of water. Third, it is to save the energy as supplying water. For it, we make the best of a gravity that is one of the cycle principle of water. Forth, to build a Dam can make a site of scenic beauty, do the role of recreation place and provide against emergencies (a fire, drought) as well as make a mild climate. Fifth, it can reduce the environment load because of sewage and garbage as making it compost. This is possible by treating biologically using composting apparatus of the dry or wet process. Sixth, it is to reduce the environmental pollution as to discharge seperating a recycable waste, an organic matter being able to make it compost. Finally, first of all, environmentally friendly inhabitant consciousness from lifestyle and production style plays an importent part for water cycle and the ecological cycle of waste and sewage.

• 한국동물위생학회지
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• 제33권1호
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• pp.1-6
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• 2010

Monoclonal antibody (mAb)-based enzyme immune-slide assay (EISA) was used for the detection of Peste des petits ruminants (PPR) virus from field samples collected from a natural outbreak. The clinicopathological study was undertaken to diagnose the case primarily of PPR. Antigen was detected from discharges and faeces of infected goats and swabs of postmortem lesions prepared on glass slide or glass plate using acetone fixation. Nasal discharge collected at the early stage of disease course or lung is an appropriate ante- or postmortem sample for this technique, respectively. Convalescent polyclonal sera collected from recovered animals which were diagnosed as PPR by EISA showed high antibody titer against PPR by C-ELISA, demonstrating the satisfactory specificity of the test. Therefore, EISA is a sensitive and specific assay to confirm PPR infection both in field and laboratory conditions and especially suitable for developing country.

• 상하수도학회지
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• 제21권1호
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• pp.101-112
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• 2007

This study has used RMA2 model and RMA4 model, which are depth-averaged two-dimensional flow and water-quality prediction models, to analyze the variation of the water-quality by the gates operation in the Seonakdong River. Sensitivity analysis is performed to get the Manning coefficient and the coefficient of eddy viscosity for RMA2 model, and to get the diffusion coefficient for RMA4 model. Since the numerical simulation using RMA2 and RMA4 models did not consider tributary pollutant load except for that of Joman River, it could make a little difference from the natural phenomenon. Nevertheless, the numerical simulation shows that the discharge of $30m^3/s$, which is the continuous inflow from the Daedong-gate, can make it possible to achieve the target water-quality (BOD 4.3mg/L) of Nakbon-N watershed about 10 days later if the Daejeo-gate could remain opened in connection with the Noksan-gate operation.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.477-483
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• 2000

Fly ash is the unburned residue resulting from the combustion of coal in utility and industrial boilers such as thermal power plants. Annually about 5 million tons of fly ash is being produced in korea. Less than 25 percent of total volume of fly ash is currently being used effectively for some ways. In the future, the volume of fly ash discharge from thermal power stations will be increasing more and more, and the development of the utilization of high volume fly ash is required. Fly ash has a lower compacted density and specific gravity than coarse grained natural aggregates but equivalent strength properties indicating that the fly ash could be used as a structural fill materials. So, clay-fly ash mixtures can be used as a fill material in the construction of embankments. Laboratory tests have been carried out to determine the physical, chemical, and geotechnical characteristics of the clay and fly ash. The fly ash is mixed with the clay in different proportions and the geotechnical characteristics of the mixtures have been studied also. In this study describes the results of the experimental study. The implications of the use of clay and clay-fly ash mixtures on the stability of embankments are discussed.

• 산업기술연구
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• 제29권A호
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• pp.9-17
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• 2009

The main purpose of this work is to analyse damages caused by debris flows during the heavy rainfall at Inje province in Kangwondo, Korea. A series of site investigations have been performed to survey the characteristics of debris flows occurred during the summer season of 2006. It has been found that major losses and costs are triggered by discharge of soil and rock fragments from landslides. During the rainfall unexpectedly high precipitation rate of 113.5mm/hour and 355mm/day was recorded, which could happen at a 80-500 year period. Comparing the period of the rainfall with the time of the landslides, it has been found that the occurrence of the landslides is directly related to heavy rainfalls. At present, several debris barriers have been built at the valleys and natural slopes have been protected by the seed spray method. It is intended to propose an appropriate solutions of restoration of landslide damages and maintenance based on findings from the current study.

• 전기화학회지
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• 제5권4호
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• pp.178-182
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• 2002

The electrochemical behavior of binder-free carbon anode, comprising of only artificial and natural graphite (AG and NG) particles, for intercalation and deintercalation of lithium ion $(Li^+)$ in aluminum chloride (AICI_3)-I-ethyl­3-methylimidazolium chloride (EMIC)-lithium chloride (LiCl)-thionyl chloride $(SOCI_2)$ room-temperature molten salt (RTMS) was studied. Binder-free carbon electrodes were fabricated using electrophoretic deposition (EPD) method. The binder-free carbon anodes provided a relatively flat charge and discharge potentials $(0\;to\;0.2V\;vs.\;Li/Li^+)$ and current capabilities $(250-340mAh{\cdot}g^{-1})$ for the intercalation and deintercalation of $Li^+$. Stability of the binder-free carbon anodes for intercalation and deintercalation of 50 cycles was confirmed.

• 혜화의학회지
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• 제18권1호
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• pp.67-81
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• 2009

1. According to causes of attack and symptoms, tinnitus is divided into two categories; deficiency and excess. Causes of excess syndrome of tinnitus were wind fire in the liver and gallbladder, phlegm fire, blood stagnation, and heat in meridian system and the causes of deficiency syndrome of tinnitus were qi deficiency or blood deficiency after an illness or delivery, yin deficiency of liver and kidney, and deficiency of sea of the marrow. 2. Tinnitus was related to the vicera and bowels, especially to liver, gallbladder and urinary bladder. 3. In regard of method of treatment, tonify kidney, nourish heart, clear the liver and discharge heat are used according to visera and bowel theory. Clear phlegm and downbear fire are used for phlegm fire. Tonify spleen and kidney is used for ancestral vessel deficiency. Dispel wind and dissipate fire can be used according to theory of five elements' motion and six kinds of natural factors. 4. The basal meridian of acupuncture and moxibustion treatment were the channels of Shaoyang.. 5. Regarding neuropsychiatric aspect of tinnitus, sudden anger and depression of mind were the main mechanism of disease and liver fire was the main cause. The prescriptions for neuropsychiatric tinnitus were Dangguiyonghuehwan, and Yongdamsagantang.

• 한국물환경학회지
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• 제37권5호
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• pp.335-343
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• 2021

Water quality prediction is essential for the proper management of water supply systems. Increased suspended sediment concentration (SSC) has various effects on water supply systems such as increased treatment cost and consequently, there have been various efforts to develop a model for predicting SSC. However, SSC is affected by both the natural and anthropogenic environment, making it challenging to predict SSC. Recently, advanced machine learning models have increasingly been used for water quality prediction. This study developed an ensemble machine learning model to predict SSC using the XGBoost (XGB) algorithm. The observed discharge (Q) and SSC in two fields monitoring stations were used to develop the model. The input variables were clustered in two groups with low and high ranges of Q using the k-means clustering algorithm. Then each group of data was separately used to optimize XGB (Model 1). The model performance was compared with that of the XGB model using the entire data (Model 2). The models were evaluated by mean squared error-ob servation standard deviation ratio (RSR) and root mean squared error. The RSR were 0.51 and 0.57 in the two monitoring stations for Model 2, respectively, while the model performance improved to RSR 0.46 and 0.55, respectively, for Model 1.

• 한국가시화정보학회지
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• 제21권2호
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• pp.34-45
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• 2023

When lithium-ion batteries operate out of the proper temperature range, their performance can be significantly degraded and safety issues such as thermal runaway can occur. Therefore, battery thermal management systems are widely researched to maintain the temperature of Li-ion battery cells within the proper temperature range during the charging and discharging process. This study investigates the cooling performance and isothermal maintenance of cooling materials by measuring the surface temperature of a battery cell with or without cooling materials, such as silicone oil, thermal adhesive, and phase change materials during discharge process of battery by the experimental and numerical analysis. As a result of the experiment, the battery pack filled with phase change material showed a temperature reduction of 47.4 ℃ compared to the case of natural convection. It proves the advanced utility of the cooling unit using phase change material that is suitable for use in battery thermal management systems.