• Journal of the Korean Institute of Gas
• /
• v.20 no.3
• /
• pp.46-51
• /
• 2016

Natural gas liquefaction process which spends a huge amount energy is operated under cryogenic conditions. Thus, many researchers have studied on minimizing energy consumption of LNG plant. However, a few studied for cost optimization have performed. This study focused on the cost analysis for the single mixed refrigerant (SMR) process, one of the simplest natural gas liquefaction process, which has different capacity. The process capacity is increased from 1 million ton per annum (MTPA) to 2.5 MTPA by 0.5 MTPA steps. According to the increase of plant size, only flow rate of natural gas and mixed refrigerant are increased and other operating conditions are fixed. Aspen Economic Evaluator(v.8.7) is used for the cost analysis and six tenths factor rule is applied to obtain multi stream heat exchanger cost data which is not supplied by Aspen Economic Evaluator. Moreover, the optimal plant sizes for different sizes of gas wells are found as the result of applying plant cost to small scale gas wells, 20 million ton (MT), 40 MT, and 80 MT. Through this cost analysis, the foundation is built to optimize LNG plant in terms of the cost.

• Journal of Environmental Health Sciences
• /
• v.41 no.6
• /
• pp.369-379
• /
• 2015

Objectives: The lack of reliable information on environmental pollution and health impacts related to asbestos contamination from abandoned mines has drawn attention to the need for a community health study. This study was performed to evaluate asbestos-related health symptoms among residents near abandoned asbestos mines located in the Chungcheong Provinces. In addition, exposure assessment for asbestos is needed although the exposure to asbestos was in the past. Methods: Past exposure to asbestos among inhabitants near abandoned asbestos mines was estimated by using surface sampling of deposited dust in indoor and outdoor residences. A total of 54 participants were divided into two groups with (34 cases) and without (20 controls) diseases related to asbestos. Surface sampling of deposited dust was carried out in indoor and outdoor residences by collecting 105 samples. Deposited dust for sampling was analyzed by polarization microscope (PLM) and scanning electron microscope?energy dispersive x-ray spectrometer (SEM-EDX) to detect asbestos. Subsequently, the elements of the deposited dust with asbestos were analyzed by SEM-EDX to assess the contribution of sources such as abandoned mines, slate and soil. Results: Among the 105 samples, asbestos was detected by PLM in 29 (27.6%) sampling points, and detected by SEM in 56 (48.6%) sampling points. Asbestos in indoor residences was detected by PLM in four sampling points, and by SEM in 12 sampling points. Asbestos detection in indoor residences may be due to ventilation between indoors and outdoors, and indicates long-term exposure. The asbestos detection rate for outdoor residences in the case group was higher than that in the control group. This can be explained as the case group having had higher exposure to asbestos, and there has been continuous exposure to asbestos in the control group as well as the case group. Conclusion: Past residential asbestos exposure may be associated with asbestosis among local residents near abandoned asbestos mines. Odds ratios were calculated for asbestos detection in outdoor residence by logistic regression analysis. Odds ratio between asbestos detection and asbestosis pulmonum was 3.36 (95% CI 0.90-12.53) (p=0.072), adjusting for age, sex, smoking status and work history with multi-variable logistic regression by PLM analysis method.

• Restorative Dentistry and Endodontics
• /
• v.27 no.4
• /
• pp.421-431
• /
• 2002

C-shaped canal configuration is very difficult to treat because that clues about preoperative canal anatomy cannot be ascertained from clinical crown morphology and limited information can be derived from radiographic examination. This study was done to get more informations about the root and canal configuration of C-shape root by 3-dimensionally reconstructing for the purpose of enhancing success rate of endodontic treatment. 30 mandibular molars with C-shaped root were selected. Six photo images from occlusal, apical, mesial, distal, buccal, lingual directions and radiographic view were taken as preoperative ones to compare them with 3-D image. After crown reduction to the level of 1-2mm over pulpal floor was performed, teeth were stored in 5.25% sodium hypochlorite solution for the removal of pulp tissue and debris. They were cleaned under running water, allowed to bench dry and embedded in a self-curing resin. This resin block was serially ground with a microtome (Accutom-50, Struers, Denmark) and the image of each level was recorded by digital camera (FinePix S1-pro, Fuji Co., Japan). The thickness of each section was 0.25mm. Photographs of serial sections through all root canal were digitized using Adobe Photoshop 5.0 and then minimum thickness of open and closed sites were measured (open site is the surface containing occluso-apical groove closed site is oppsite). After dizitization using 3-D Doctor (Able software Corp, USA). 3D reconstruction of the outer surface of tooth and the inner surface of pulp space was made. Canal classsification of C-shaped roots was performed from this 3-D reconstructed image. The results were as follows : 1. Most C-shape rooted teeth showed lingual groove (28/30). 2 According to Vertuccis' calssification, type I, II, III, IV, VII were observed. but also new canal types suck as 2-3-2, 1-2-3-2. 2-3-2-1, 2-3-2-3 were shown. 3 There was little difference in minimum thickness on coronal and apical portions, but open site were thinner than closed site on mid portion. Conclusively, 3D reconstruction method could make the exact configurations of C-shape root possible to be visualized and analyzed from multi-directions. Data from minimum thickness recommend cleaning and shaping be more carefully done on dangerous mid portion.

• Journal of Biomedical Engineering Research
• /
• v.25 no.3
• /
• pp.189-194
• /
• 2004

Pixel values of contrast enhanced computed tomography (CE-CT) images are randomly changed. Also, the middle liver part has a problem to segregate the liver structure because of similar gray-level values of a pancreas in the abdomen. In this paper, an automatic liver segmentation method using a partial histogram threshold (PHT) algorithm is proposed for overcoming randomness of CE-CT images and removing the pancreas. After histogram transformation, adaptive multi-modal threshold is used to find the range of gray-level values of the liver structure. Also, the PHT algorithm is performed for removing the pancreas. Then, morphological filtering is processed for removing of unnecessary objects and smoothing of the boundary. Four CE-CT slices of eight patients were selected to evaluate the proposed method. As the average of normalized average area of the automatic segmented method II (ASM II) using the PHT and manual segmented method (MSM) are 0.1671 and 0.1711, these two method shows very small differences. Also, the average area error rate between the ASM II and MSM is 6.8339 ％. From the results of experiments, the proposed method has similar performance as the MSM by medical Doctor.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.36 no.1
• /
• pp.91-95
• /
• 2009

The use of stainless steel crowns are indicated for restoration of primary or permanent molars with proximal dental caries, extensive dental caries, or previous pulp treatment with increased danger of tooth fracture. Stainless steel crowns were introduced by Humphrey in 1950. For their improved durability, longevity, and success rate, they have been strongly considered for restoring extensive and multi-surfaced dental caries of molars in pediatric dentistry. However, they also have shortcomings, such as possibility of pulpal exposure or damaging proximal surface of adjacent teeth. In addition, when oversized stainless steel crowns are used, eruption of the adjacent permanent teeth may be disturbed by their prominent margin. As a means to compensate the shortcomings of stainless steel crowns, use of orthodontics bands may be considered. It is an alternative restoration method, where an orthodontic band is placed on a tooth first and cavity is restored with filling material, such as composite resin, glass ionomer, or amalgam. The use of an orthodontic band is indicated for molar restoration with cervical dental caries, extensive dental caries, enamel hypoplasia, or previous pulp treatment. Because it requires shorter chair time compared to stainless steel crown, its application is very useful for children with poor behavior. However, restoration using an orthodontic band requires good oral hygiene after its application. This case report illustrates the conservative restoration of primary molars and permanent molars with extensive dental caries using orthodontic bands.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.41 no.2
• /
• pp.134-144
• /
• 2014

The aim of this study was to investigate changes in treatment patterns within pediatric dentistry departments by analyzing the distribution of patients and treatment trends. To that end, treatment charts based on electronic medical records (EMR) from the Yonsei University Dental Hospital from 2008 to 2012 were collected and analyzed. The results showed a decrease in the number of new patients and patients cared for by non-specialists, while the number of foreign patients has increased. The under 2 years-old group accounted for a large portion of new patients. Dental caries, dental trauma, and malocclusion ranked as the top complaints. In terms of restoration treatment, the proportion of patients receiving composite resin, amalgam, and sealant has decreased, whereas self-curing glass ionomer and preventive resin restoration have increased. Single-visit endodontic treatment has been increasing, with a decreasing trend in multi-visit endodontic treatment. The rate of conservative pulp treatment, such as pulp capping and pulpotomy, has increased. For reducing patient anxiety, treatments under sedation have increased, especially with the use of nitric oxide. This investigation into the latest treatment trends and patient characteristics is expected to help pediatric dentists to make appropriate treatment plans.

• Korean Journal of Environmental Agriculture
• /
• v.33 no.4
• /
• pp.282-289
• /
• 2014

BACKGROUND: Methane($CH_4$) is considered as the secondmost potent greenhouse gas after carbon dioxide ($CO_2$). Methanogenesis is an enzyme-mediated multi-step process by methanogens. In the penultimate step, methylated Co-M is reduced by methyl Co-M reductase (MCR) to $CH_4$ involving a nickel-containing cofactor F430. The activity of MCR enzyme is dependent on the F430 and therefore, the bioavailability of Ni to methanogens is expected to influence MCR activity and $CH_4$ production in soil. In this study, different doses of EDTA(Ethylene Diamine Tetraacetic Acid) were applied in flooded soils to evaluate their suppression effect on methane production by chelating Ni of methanogenesis cofactor. METHODS AND RESULTS: EDTA was selected as chelating agents and added into wetland and rice paddy soil at the rates of 0, 25, 50, 75, and $100mmol\;kg^{-1}$ before 4-weeks incubation test. During the incubation, cumulative $CH_4$ production patterns were characterized. At the end of the experiment, soil samples were removed from their jars to analyze total soil Ni and water-soluble Ni content and methanogen abundance. Methane production from 100 mmol application decreased by 55 and 78% in both soils compared to that from 0 mmol. With increasing application rate of EDTA in both soils, water-soluble Ni concentration significantly increased, but total soil Ni and methanogen activities showed negative relationship during incubation test. CONCLUSION: The decrease in methane production with EDTA application was caused by chelating Ni of coenzyme F430 and inhibiting methanogenesis by methyl coenzyme M reductase. Consequently, EDTA application decreased uptake of Ni into methanogen, subsequently inhibited methanogen activities and reduced methane production in flooded soils.

• Journal of Energy Engineering
• /
• v.8 no.2
• /
• pp.224-232
• /
• 1999

Latent heat storage system using micro-encapsuled phase change material is effective method for floor heating of house and building. The temperature profile in capsule block and flow rate of hot water are important parameters for the development of heat storage system. In the present study, a mathematical model based on 3-D, non-steady state, Navier-Stokes equations, scalar conservation equations and turbulence model ($\kappa$-$\varepsilon$), is used to predict the temperature profiles in capsule and the velocity vectors in hot water pipe. The multi-block grids and fine grids embedding are used to join the circle in hot water pipe and square in capsule block. The phase change process of the capsule is quite complex not only because the size of phase change material is very small, but also because phase change material is mixed with the cement to form thermal storage block. In calculation, it's assumed that the phenomena of phase change is limited only the thermal properties of phase change material and the change of boundary is not happened in capsule. The purpose of this study is to calculate the temperature profiles in capsule block and velocity vectors in hot water pipe using the numerical calculation. Two kinds of thermal boundary condition were considered, the first (case 1) is the adiabatic condition for the both outside surfaces of the wall, the second (case 2) is the case in which one surface is natural convection with atmosphere and another surface is adaibatic. Calculation results are shown that the temperature profile in capsule block for case 1 is higher than that for case 2 due to less heat loss in adaibatic surface. Specially, in the domain of near Y=0, the difference of temperature is greater in case 1 than in case 2. The detailed experimental data of capsule block on the temperature profile and the thermal properties such as specific heat and coefficient of heat transfer with the various temperature are required to predict more exact phenomena of heat transfer.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.18 no.5
• /
• pp.1232-1236
• /
• 2004

In the Far-Eastern traditional medicine, Oi[Energy] implies a wide range of meaning and is emphasized. There is nothing that is not related to this Qi, as seen in physiology, pathology, the relationship between human body and nature, the movements of intestines and gyeongnak[energy networks], the process of outbreak and change of illness, remedial laws, the features and effects of drugs, and so on. Accordingly, Nei Jing also says, 'every sickness arises from OL' The Qi has multi-meanings, and each of lots Of past physicians researched and analyzed it in different perspective, thus making the Qi-theories much richer. Still. there were not so many physicians who discussed the theme of Daqi. The denomination of Daqi is seen in Nei Jing and Jin Gui Yao Lue, and the physicians like Yu Chang in Ming dynasty and Zhang Xi Chun in Cheng dynasty, etc. applied and utilized Daqi by exploring its functional actions for human life and associating it with clinical practices. Yu Chang said that Daqi is Xiong Zong Yangqi[Positive Energy in Breast] governing every Qi, and that if this Qi is full, it spreads through body and protects the body from sickness, and vice versa. Summarizing his researches on the Daqi in Jin Gui Yao Lue and on the opinions of Yu Chang as well as his experiences, Chang Xi Chun maintained that the Qi accumulated in breast must be named Daqi, which constitutes the contents of Zongqi[Chief Energy] mentioned in Nei Jing. Once the Qi is vacant, breathing is not smooth, whole body is enervated, spirit becomes dim, thinking ability falls drastically. Furthermore, if the Qi is extremely vacant or more worsens, breathing stops. And he prescribed the medicines including Sheng Xian Tang as remedies against the symptom of Daqi XiaXian[Fall in Great Energy]. The recognitions of Daqi by Yu Chang and Zhang Xi Chun are consistent with each other. At any rate, their theories and prescriptions may be high in practical value in contemporary clinics.

• Archives of Plastic Surgery
• /
• v.37 no.5
• /
• pp.577-582
• /
• 2010

Purpose: When reconstruction for patients who have the large contralateral breast or a following large defect after mastectomy is required, conventional pedicled TRAM flap shows the unpredictable occurrence of fat necrosis and skin flap loss in a relatively high percentage due to insufficient blood supply. In an effort to obtain more stable TRAM flap blood circulation, we have performed a supercharged technique using deep inferior epigastric perforators (DIEP) with conventional pedicled TRAM flap. Methods: From September of 2006 to December of 2008, Fourteen supercharged TRAM flap were performed for breast reconstruction after modified radical mastectomy. The contralateral DIEP was anastomosed to the internal mammary vessels in contralateral pedicled TRAM flap or thoracodorsal vessels in ipsilateral pedicled TRAM flap. Nutrient vessels were selected by Multi-Detector Computed tomography (MD-CT) modalities. For the nutrient vessel, we used deep inferior epigastric vessels (DIEV) of the ipsilateral side in 8 patients, DIEV of the contralateral side in 6 patients. In addition, for the recipient vessel, we used thoracodorsal vessels in 8 patients, internal mammary vessels in 5 patients, intercostals artery perforators in 1 patient. Results: The mean age was 46.8 years and the average follow-up interval was 14 months. There were 11 immediate and 3 delayed breast reconstructions. Fat necrosis incidence rate in supercharged TRAM group was lower than in conventional TRAM flap group. There were no differences of the incidences of abdominal hernia in both groups. Conclusion: The supercharged TRAM flap produces an improvement in vascularity that permits use of all four zones of the flap. The breast reconstruction with supercharged technique is reliable and valuable methods which provide sufficient soft tissue from abdomen without significant complications.