• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.2
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• pp.135-146
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• 2020

To define an interface in a conventional level-set method, an analytical function must be revealed for an interfacial geometry. However, it is not always possible to define a functional form of level sets when interfaces become complex in a Cartesian coordinate system. To overcome this difficulty, we have developed a new level-set formalism that discriminates the interior from the exterior of a CAD modeled interface by parameterizing the stereolithography (STL) file format. The work outlined here confirms the accuracy and scalability of the hydrodynamic reactive solver that utilizes the new level set concept through a series of tests. In particular, the complex interaction between shock and geometrical confinements towards deflagration-to-detonation transition is numerically investigated. Also, a process of flame spreading and damages caused by point source detonation in a real-sized plant facility have been simulated to confirm the validity of the new method built for reactive hydrodynamic simulation in any complex three-dimensional geometries.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.3
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• pp.121-129
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• 2014

This study was carried out to research the locations and comprehensive functions of Chinese unique Banwoldang(half-moon shaped pond) appeared at the traditional Chinese villages. Based on the research, the time of Banwoldang being introduced into Chinese traditional culture could date back to Yuan Dynasty and villages that have Banwoldang mainly distributed in the south of the Yangtze River of China where wealthy and high class have lived. Bamwoldangs were mostly built at the front of the village clan halls for the prosperity of the whole clan, The main reason of Banwoldang construction was to complete Feng Shui functions and its goal from the point of Feng Shui in Chinese ancient villages was replenishing the power of location, including increasing the probability of passing the imperial examination for villagers, multiplying riches, minimizing the fire accident and perfecting the geomantic pattern 'leaning against the hill and facing the water(背山臨水)' of villages. Other functions of Banwoldang were found as the place for the community meeting, fish farming and protection of village from enemy. In this research, the reasons of Banwoldang location and values of its various functions were found. But Banwoldang is disappearing rapidly at the Chinese modern villages because there is no interest in traditional culture. Banwoldang is one of unique elements of Chinese culture that must be preserved, so its meaning and value should be lasted well as the Chinese traditional cultures.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.588-596
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• 1996

The optimum conditions of the 1st and 2nd distillation had been investigated to obtaine a high quality monomeric MDI and fire reactive polymeric MDI by purification of crude MDI. Effect of additives on the monomeric MDI's color change, dimerization and the reactivity of polymeric MDI with standard polyol system has been tested. When the monomeric MDI yield is approximately 32%, 4,4'-MDI content is above 98% in the monomeric MDI at the 1st distillation. When the separation ratio of initial portion and residue percentage, reflux ratio are set at respectively, approximately 20wt%, 9wt%, above 2 in order to minimize the content of 2,4'-MDI in monomeric MDI, the freezing point of final distilled monomeric MDI is above $38.4^{\circ}C$. Since the monomeric MDI is inherently unstable in the room condition, monomeric MDI easily changes it's color and conducts self-polymerization reaction. To increase the stability of monomeric MDI, the composition of antioxidant, which is composed of phenolic 1st antioxidant, phosphorus 2nd antioxidant, UV absorbent and Hindered amine light stabilizer are used, and benzoyl chloride as antipolymerization agent test are that APHA color is less than 20, dimer content is remained less than 0.36wt% after 45 days storage of monomeric MDI.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.2
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• pp.201-207
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• 2010

Recently, about 600 cases of marine accidents occur annually in Korea. According to many studies and analyses on occurrence of marine accidents, 70~80% of marine accidents were caused by human factors. Among the human factors, navigation officers' fatigue is very important factor. Although navigation officers' fatigue serves as an important role in marine accidents, there is no method to exactly examine the degree of officers' fatigue. Accordingly, this study analyzed human factors according to types of marine accidents and extracted important five factors affecting navigation officers' fatigue through the questionnaire survey by means of literatures and 5-point scale. In addition, evaluation factors of marine accident risks caused by fatigue factors were divided and structured by using ISM. Lastly, it found out the importance of each fatigue factor drawn by AHP and decided marine accidents that were most highly caused by navigation officers' fatigue in order. At the result, weights were high as sleep time 0.385, stress 0.302, health condition 0.139, rest time 0.099, alcohol and drug 0.074 in fatigue factors, and death and injury 0.328, collision 0.308, grounding 0.195, sinking 0.094, fire accident 0.075 in evaluation factors of marine accident risks. Therefore, the control plan to lower marine accident risks should be prepared on the basis of high weight factors.

• Journal of Acupuncture Research
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• v.18 no.6
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• pp.240-249
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• 2001

Obejective : Based on ${\ll}$sixty-ninth Nan${\gg}$ (${\ll}$難經${\cdot}$六十九難${\gg}$) the interpromoting of the five element's balance method to discuss following 'when deficiency than should strengthen mother and when excessive than eliminate son' theories. Method : This strengthening and eliminating method is based on Jang-bu organ's balance method when 'east is excessive (liver excessive (肝實 )) and west is deficiency (lung deficiency (肺虛))' then 'eliminate the south and strengthen the north's method. Results : The seventy-fifth Nan (${\ll}$難經${\cdot}$七十五難${\gg}$) explains' son effects mother's excessive and mother effects son's deficiency' theory where it balance method of the inter-overacting five elements controlling Jang-bu organ's differentiations. The eighty-first Nan (${\ll}$難經${\cdot}$八十一難${\gg}$) explains strengthening-eliminating method of 'lung excessive and liver deficiency.' Since there are two different perspective of seventy-fifth and eighty-first Nan, we must compare and discuss to make right point of view. Conclusion : the treatment method in ${\ll}$Nan kyoung sixty ninth nan${\gg}$ could be understood as a view of five element constitutional theory (五行體質理論), the treatment method in ${\ll}$Nan kyoung seventyty-fifth nan${\gg}$ of eleminating fire and strengthning water in case of liver excess and lung defficiency and the treatment method in ${\ll}$Nan kyoung eighty-first nan${\gg}$ of strengthning liver and eleminating lung in case of lung excess and liver defficiency could be understood as a view of the yin-yan constitutional theory (陰陽體質理論).

• Journal of Physiology & Pathology in Korean Medicine
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• v.26 no.1
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• pp.10-18
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• 2012

In this paper, to find out how different the treatment of special individuals named 'old people' is with that of ordinary cases, Dongeuibogam(東醫寶鑑) was chosen as the study material and some parts in it where the symptoms of old people in the same disease category were treated in different ways were excerpted to analyze the tendency of pathological symptoms and prescriptions in the physiological perspective. As the result of analysis on the parts in Dongeuibogam(東醫寶鑑) where the old people were treated in different ways, it turned out that 65 prescriptions were used in 24 pathological symptoms. The 24 symptoms are included mainly in chapters of 'inner view(內景)' and 'outer form(外形)'. They are including the pathological symptoms which had been presented as general geriatric symptoms and also seems to have added other symptoms which should be clinically reflected in the specialty of treatment for geriatric diseases. The 65 prescriptions are also recorded mainly in chapters of 'inner view(內景)' and 'outer form(外形)'. The herbs used for them were sweet and warm herbs such as Rehmannia glutinosa (Gaertner) Libosch(熟地黃), Angelica gigas Nakai(當歸), Panax ginseng C. A. Mey(人蔘) and Atractylodes macrocephala Koidz(白朮) that can support the essence blood of liver and kidney and the energy of spleen, lung and stomach. Those herbs could be added or subtracted according to the symptom. It seems to have resulted from the treatment method that old people was applied to old people in consideration of their physiological features. When the 24 symptoms and 65 prescriptions for geriatric diseases different from ordinary ones in Dongeuibogam(東醫寶鑑) were considered in the physiological view point, it could be seen that each pathological symptom was manifested as a exhaustion of kidney qi(腎氣枯渴) which was a characteristic physiologic state of old people. Through this, it could be seen that the use of prescriptions was also made to mitigate the body fluid deficiency(津液不足), the kidney yin inner heat(腎陰內熱), the heart spirit void and loss(心神虛損), the kidney yang deficiency(腎陽不足), the spleen failing in transportation(脾失健運), the spleen yang deficiency(脾陽不足), the liver fire inner movement(肝火內動) and the lung energy void and loss(肺氣虛寒).

• Journal of Korea Water Resources Association
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• v.54 no.5
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• pp.301-309
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• 2021

In this study, we tried to improve the performance of the existing U-net-based deep learning rainfall prediction model, which can weaken the meaning of time series order. For this, ConvLSTM2D U-Net structure model considering temporal consistency of data was applied, and we evaluated accuracy of the ConvLSTM2D U-Net model using a RainNet model and an extrapolation-based advection model. In addition, we tried to improve the uncertainty in the model training process by performing learning not only with a single model but also with 10 ensemble models. The trained neural network rainfall prediction model was optimized to generate 10-minute advance prediction data using four consecutive data of the past 30 minutes from the present. The results of deep learning rainfall prediction models are difficult to identify schematically distinct differences, but with ConvLSTM2D U-Net, the magnitude of the prediction error is the smallest and the location of rainfall is relatively accurate. In particular, the ensemble ConvLSTM2D U-Net showed high CSI, low MAE, and a narrow error range, and predicted rainfall more accurately and stable prediction performance than other models. However, the prediction performance for a specific point was very low compared to the prediction performance for the entire area, and the deep learning rainfall prediction model also had limitations. Through this study, it was confirmed that the ConvLSTM2D U-Net neural network structure to account for the change of time could increase the prediction accuracy, but there is still a limitation of the convolution deep neural network model due to spatial smoothing in the strong rainfall region or detailed rainfall prediction.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.54-59
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• 2022

This paper is a purpose to study and analyze the failure examples for timing belt, camshaft position sensor and ignition coil of LPG automotive engine. The first example, whe the service man install the front case bracket of engine, he excessively tightened up a 12mm bolt for being fixed of brackct. As a results, the bolt was separated from joint part so that it was put in between the crankshaft sprocket. Therefore the belt was broken off because of interference between timing belt and sprocket tooth. The second example, it verified the disharmony phenenomen of engine that the gap of the camshaft position sensor and camshaft senseing point assembled on cylinder head part was small more than iregular value so that the it was generated senseing damage phenomenon by pulse signal misconduct. The third example, it was found the engine disharmony phenomenon that the fire in the ignition coil was leaked by inner damage of Number 2 ignition coil.Therefore, the the manager of a car throughtly have to inspect not in order to arise the failure symptoms.

• Korean Journal of Materials Research
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• v.32 no.1
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• pp.9-13
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• 2022

Bullets flying with a light from the back are called "tracers". Tracers are ignited by the combustion gas of the propellant and emit bright light that allows the shooter to visually trace the flight path. Therefore, tracers mark the firing point for allies to assist shooters to hit target quickly and accurately. Conventional tracers are constructed with a mixture of an oxidizing agent, raw metal, and organic fuel. Upon ignition, the inside of the gun can be easily contaminated by the by-products, which can lead to firearm failure during long-term shooting. Moreover, there is a fire risk such as forest fires due to residual flames at impact site. Therefore, it is necessary to develop non-combustion type luminous material; however, this material must still use the heat generated from the propellant, so-called "thermoluminescence (TL)". This study aims to compare the TL emission of Dy³⁺, La³⁺ and Ho³⁺ doped MgB₄O₇ phosphors prepared by solid state reaction. The crystal structures of samples were determined by X-ray diffraction and matched with the standard pattern of MgB₄O₇. Luminescence of various doses (200 ~ 15,000 Gy) of gamma irradiated Dy³⁺, La³⁺ and Ho³⁺ (at different concentrations of 5, 10, 15 and 20 %) doped MgB₄O₇ were recorded using a luminance/color meter. The intensity of TL yellowish (CIE x = 0.401 ~ 0.486, y = 0.410 ~ 0.488) emission became stronger as the temperature increased and the total gamma-ray dose increased.

• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.15-24
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• 2007

Two kinds of temperature monitoring technology have been introduced in this study, which can measure coincidently temperatures at many points along a single length of cable. One is to use a thermal sensor cable comprizing of addressable thermal sensors. The other is to use an optic fiber sensor with Distributed Temperature Sensing (DTS) system. The differences between two technologies can be summarized as follows: A thermal sensor cable has a concept of "point sensing" that can measure temperature only at a predefined position. The accuracy and resolution of temperature measurement are up to the capability of the individual thermal sensor. On the other hand, an optic fiber sensor has a concept of "distributed sensing" because temperature is measured practically at all points along the fiber optic cable by analysing the intensity of Raman back-scattering when a laser pulse travels along the fiber. Thus, the temperature resolution depends on the measuring distance, measuring time and spatial resolution. The purpose of this study is to investigate the applicability of two different temperature monitoring techniques in technical and economical sense. To this end, diverse experiments with two techniques were performed and two techniques are applied under the same condition. Considering the results, the thermal sensor cable will be well applicable to the assessment of groundwater flow, geothermal distribution and grouting efficiency within about loom distance, and the optic fiber sensor will be suitable for long distance such as pipe line inspection, tunnel fire detection and power line monitoring etc.