• Investigative Magnetic Resonance Imaging
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• v.2 no.1
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• pp.73-82
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• 1998

Purpose : A precise NMR technique for measuring the rate of water exchange and cell membrane permeability across the hepatocyte membrane using liver-specific MR contrast agent is described. Materials and Methods : The rat hepatocytes isolated by perfusion of the livers were used for the NMR measurements. All experiments were performed on an IBM field cycling relaxometer operating from 0.02MHz to 60 MHz proton Larmor frequency. spin-echo pulse sequence was empolyed to measure spin-lattice relaxation time, T1. The continuous distribution analysis of water proton T1 data from rat hepatocytes containing low concentrations of the liver specific contrast agent, Gd-EOB-DTPA, modeled by a general two compartment exchange model. Results : The mean residence time of water molecule inside the hepatocyte was approximately 250 msec. The lower limit for the permeability of the hepatocyte membrane was $(1.3{\pm}0.1){\;}{\times}{\;}10^{-3}cm/sec$. The CONTIN analysis, which seeks the natural distribution of relaxation times, reveals direct evidence of the effect of diffusive exchange. the diffusive water exchange is not small in the intracellular space in the case of hepatocytes. Conclusions : Gd-EOB-DTPA, when combined with continuous distribution analysis, provides a robust method to study water exchange and membrane permeability in hepatocytes. Water exchange in hepatocyte is much slower thatn that in red blood cells. Therefore, tissue-specific contrast agent may be used as a functional agent to give physiological information such as cell membrane permeability.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.170-174
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• 2008

Recently, a problem related to the thermal management in portable electronic and telecommunication devices is becoming issued. That is due to the trend of slimness of the devices, so it is not easy to find the optimal thermal management technology for the devices. From now on, a pressed circular type cooling device has been mainly used, however the cooling device with thin thickness is becoming needed by the inner space constraint. In the present study, the silicon and metal flat plate type cooling device with the separated vapor and liquid flow path was designed and fabricated. Through the experimental study, the normal isothermal characteristic by vapor-liquid phase change was confirmed and the cooling device with 70mm of total length showed 6.8W of the heat transfer rate within the range of $4{\sim}5^{\circ}C$/W of thermal resistance. In the meantime, the metal cooling device was developed for commercialization. The device was designed to have all structures of evaporator, vapor flow path, liquid flow path and condenser in one plate. And an envelope of that could be completed by combining the two plates of same structure and size. And the simplicity of fabrication process and reduction of manufacturing cost could be accomplished by using the stamping technology for fabricating large flow paths relatively. In the future, it will be possible to develop the commercialized cooling device by revising the fabrication process and enhancing the thermal performance of that.

• Journal of Periodontal and Implant Science
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• v.37 no.2
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• pp.237-249
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• 2007

This study was performed to evaluate the effect of membrane exposure on new bone formation when guided bone regeneration with perforated titanium membrane on atrophic alveolar ridge. The present study attempted to establish a GBR model for four adult beagle dog premolar. Intra-marrow penetration defects were created on the alveolar ridge(twelve weeks after extraction) on the mandibular premolar teeth in the beagle dogs. Space providing perforated titanium membrane with various graft material were implanted to provide for GBR. The graft material were demineralized bovine bone(DBB), Irradiated cancellous bone(ICB) and demineralized human bone powder(DFDB). The gingival flap were advanced to cover the membranes and sutured. Seven sites experienced wound failure within 2-3weeks postsurgery resulting in membrane exposure. The animals were euthanized at 4 weeks postsurgery for histologic and histometric analysis. The results of this study were as follows: 1. There was little new bone formation at 4 weeks postsurgery. irrespectively of membrane exposure. 2. There was significant relationship between membrane exposure and bone graft resorption(P<0.05), but no relation between membrane exposure and infiltrated connective tissue. 3. There was much bone graft resorption on DFDB than ICB and DBB. 4. The less exposure was on the perforated titanium membrane, the more dense infiltrated connective tissue was filled under the membrane when grafted with ICB and DBB. but there was no relationship between the rate of membrane exposure and the percentage of infiltrated connective tissue area and no relationship between the percentage of the area in the infiltrated connective tissue and in the residual bone graft. Within the above results, bone formation may be inhibited when membrane was exposed and ICB and DBB were more effective than DFDB as a bone graft material when guided bone regeneration.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.102-108
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• 2010

Impaction is the cessation of eruption process caused by physical obstacles on the eruption pathway, abnormal tooth position, or lack or space. It often occurs in association with supernumerary teeth, odontogenic tumor, or cystic lesions, and ameloblastic fibroma is one of the odontogenic tumors that can cause impaction of teeth. In many cases, ameloblastic fibroma occurs in association with one or more unerupted teeth. The proper management of ameloblastic fibroma is determined between conservative resection or more aggressive block resection, based size and morphologic features of the lesion and age of the patient. This is a case of a 8 year and 6 month old boy whose lower left permanent molar showed eruption disturbance. The impacted tooth was successfully repositioned favorably through surgical exposure and orthodontic traction using a modified halterman appliance. Long term follow-up, longer than 10 years, is planned considering relatively high recurrence rate and possibility of malignant transformation of ameloblastic fibroma, which cause impaction of the lower left permanent molar in this case.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.298-306
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• 2016

Planting date shift is one of the means of adapting to climate change in Kimchi Cabbage growers in major production areas in Korea. This study suggests a method to estimate the potential yield of Kimchi Cabbage based on daily temperature accumulation during the growth period from planting to maturity which is determined by a plant phenology model tuned to Kimchi Cabbage. The phenology model converts any changes in the thermal condition caused by the planting date shift into the heat unit accumulation during the growth period, which can be calculated from daily temperatures. The physiological maturity is estimated by applying this model to a variable development rate function depending either on growth or heading stage. The cabbage yield prediction model (Ahn et al., 2014) calculates the potential yield of summer cabbage by accumulating daily heat units for the growth period. We combined these two models and applied to the 1km resolution climate scenario (2000-2100) based on RCP8.5 for South Korea. Potential yields in the current normal year (2001-2010) and the future normal year (2011-2040, 2041-2070, and 2071-2100) were estimated for each grid cell with the planting dates of July 1, August 1, September 1, and October 1. Based on the results, we divided the whole South Korea into 810 watersheds, and devised a three - dimensional evaluation chart of the time - space - yield that enables the user to easily find the optimal planting date for a given watershed. This method is expected to be useful not only for exploring future new cultivation sites but also for developing cropping systems capable of adaptation to climate change without changing varieties in existing production areas.

• Korean Journal of Health Education and Promotion
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• v.19 no.2
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• pp.23-43
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• 2002

Purpose: The purpose of this study is to examine and analyse factors related to the actual status and practice of breast-feeding during an infant period to grasp elements detrimental to breast-feeding and, therefore, provide basic information useful for its effective practice and encouragement. Method: From April 1 to June 30, 2001, this study was carried out with the mothers of 337 who were 6 months old, as of the surveyed date, of infants born in 2002 and registered in Seongju-gun Public Health Center, Gyeongsangbug-do Province. The method for its survey included both of the visiting and telephone interviews, and questions were mainly about the mothers' general characteristics(3 questions), infants' general characteristics(3 questions), environmental characteristics of infant delivery( 4 questions), support to breast-feeding(4 questions), understanding of breast-feeding(5 questions), and feeding type during the 1 to 6-month period after birth. Result: 1. The feeding type during the I-month period after birth showed that the breast-feeding accounted for 42.4%, which was higher than dry milk-feeding(30%) or mixed milk-feeding(26.8%). However, it began to be lower than the dry milk-feeding from the 2-month period after birth. During the 6-month period, the breast-feeding accounted for 28.6% which was lower than 56.5% of the dry milk-feeding. 2. The mothers who were encouraged by their delivery clinic to and were educated to breast-feed infants accounted for 55.4% and 41.4%, respectively, which were relatively low. The understanding of breast-feeding indicated that the responses were positive from the view point of mother ＆ infant health, but negative from mother's physical form. 3. It was shown that the lower the educational background of mother(p〈0.05) and the higher the unemployment of mother(p〈0.001), the higher the positive understanding of breast-feeding, and that the higher the entire support to breast-feeding, the more positive their understanding. 4. It was also shown that the lower the educational background of mother(p〈0.05), the higher the unemployment of mother(p〈0.001), the more the experience in breast-feeding at a delivery clinic(p〈0.01) and the faster the initial feeding(p〈0.001), the higher the rate of breast-feeding. 5. The factor having an effect on breast-feeding included a delivery clinic's encouragement to breast-feed(p〈0.001), understanding of breast-feeding(p〈0.01), father's comment on feeding method(p〈0.05) and mother's employment(p〈0.05). Discussion: In order to encourage the breast-feeding, as shown above, it is required, fist of all, to offer pregnant women an education about importance and excellence of breast-feeding and its appropriate method before delivery in advance to result in a positive comprehension of the breast-feeding. To do that, both the publicity activities and program development designed to encourage the breast-feeding must be performed in advance at the government level. In addition to that, the mother-infant space as ‘rooming-in’ available for breast-feeding immediately after delivery must be prepared on the basis of legal and administrative support. Finally, female employees' leave after childbirth must be performed for the purpose of productive welfare and circumstances also be prepared for breast-feeding, such as a children's home at work.

• Journal of the Korean earth science society
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• v.29 no.7
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• pp.579-585
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• 2008

The time-dependent evolution of disk mass for outburst limit cycle in a black hole microquasar is calculated based on the non-linear hydrodynamic model of thermally unstable accretion disk. The physical parameters such as black hole mass, disk size and mass transfer rate are adopted to reproduce the historical 1975 outburst observed in a prototype black hole X-ray nova A0620-00. The time-dependent effect of irradiation from the central hot region to the disk is considered in two ways: direct irradiation and indirect irradiation reflected from hot accretion flow above the disk. The accretion disk thermal instability model can account for the bolometric luminosity appropriate to typical characteristics of system luminosity observed in X-ray transients during the whole cycle of the outburst evolution. The maximum mass of the accretion disk, ${\sim}4.03{\times}10^{24}g$, is achieved at the ignition of an outburst, and the minimum value, ${\sim}8.54{\times}10^{23}g$, is reached during the cooling decay to quiescence. The disk mass varies ${\sim}5$ times during outburst limit cycle.

• Journal of the Korean association of regional geographers
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• v.3 no.1
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• pp.99-113
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• 1997

The purpose of this study is to find out about the cause and adaptation process of urban households going to rural areas for agricultural management(Kwihyang nongga) through the microscopic analysis of a case study. Research results are summarized in the followings. The cause of Kwihyang nongga before the 1980s was generally due to the social causes like the support of dependent family or rural-to-urban migrants' maladjustment in urban society. After the 1980s, however, it was related to the economic reasons such as the increase of households' income by commercial agriculture more than the social ones. Most of Kwihyang nongga was traditionally the households which came back to their native places, rural areas. Recently the urban households which did not originally come from rural areas are going to rural space because of the cultivation of high profit oriented agricultural products. Recent Kwihyang nongga increased the size of commercial agriculture through leased farmland, not by a purchase of agricultural land. Even though the number of Kwihyang nongga is now a few, it is expected that the influence of Kwihyang nongga on rural society will be various and high because it consists of young generation. The increase of Kwihyang nongga may be one of the ways to mitigate the decreasing rate of utilization of agricultural lands due to the labor shortage of rural areas after industrialization. To solve rural problems related to underpopulation, it is necessary to establish the active plicies of helping Kwihyang nongga. The actions for Kwihyang nongga ought to emphasize the improvement of educational conditions and living facilities as well as financial aids and the improvement of farming conditions.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.6
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• pp.514-528
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• 2004

An emotion-based video scene retrieval algorithm is proposed in this paper. First, abrupt/gradual shot boundaries are detected in the video clip representing a specific story Then, five video features such as 'average color histogram' 'average brightness', 'average edge histogram', 'average shot duration', and 'gradual change rate' are extracted from each of the videos and mapping between these features and the emotional space that user has in mind is achieved by an interactive genetic algorithm. Once the proposed algorithm has selected videos that contain the corresponding emotion from initial population of videos, feature vectors from the selected videos are regarded as chromosomes and a genetic crossover is applied over them. Next, new chromosomes after crossover and feature vectors in the database videos are compared based on the similarity function to obtain the most similar videos as solutions of the next generation. By iterating above procedures, new population of videos that user has in mind are retrieved. In order to show the validity of the proposed method, six example categories such as 'action', 'excitement', 'suspense', 'quietness', 'relaxation', 'happiness' are used as emotions for experiments. Over 300 commercial videos, retrieval results show 70% effectiveness in average.

• Journal of KIISE
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• v.42 no.5
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• pp.642-651
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• 2015

A vanishing point is a point where parallel lines converge, and they become evident when a camera's lenses are used to project 3D space onto a 2D image plane. Vanishing point detection is the use of the information contained within an image to detect the vanishing point, and can be utilized to infer the relative distance between certain points in the image or for understanding the geometry of a 3D scene. Since parallel lines generally exist for the artificial structures within images, line-detection-based vanishing point-detection techniques aim to find the point where the parallel lines of artificial structures converge. To detect parallel lines in an image, we detect edge pixels through edge detection and then find the lines by using the Hough transform. However, the various textures and noise in an image can hamper the line-detection process so that not all of the lines converging toward the vanishing point are obvious. To overcome this difficulty, it is necessary to assign a different weight to each line according to the degree of possibility that the line passes through the vanishing point. While previous research studies assigned equal weight or adopted a simple weighting calculation, in this paper, we are proposing a new method of assigning weights to lines after noticing that the lines that pass through vanishing points typically belong to artificial structures. Experimental results show that our proposed method reduces the vanishing point-estimation error rate by 65% when compared to existing methods.