• Analytical Science and Technology
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• v.28 no.6
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• pp.453-459
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• 2015

Split-flow thin cell fractionation (SPLITT fractionation, SF) is a particle separation technique that allows continuous (and thus a preparative scale) separation into two subpopulations based on the particle size or the density. In SF, there are two basic performance parameters. One is the throughput (TP), which was defined as the amount of sample that can be processed in a unit time period. Another is the fractionation efficiency (FE), which was defined as the number % of particles that have the size predicted by theory. Full-feed depletion mode (FFD-SF) have only one inlet for the sample feed, and the channel is equipped with a flow stream splitter only at the outlet in SF mode. In conventional FFD-mode, it was difficult to extend channel due to splitter in channel. So, we use large scale splitter-less FFD-SF to increase TP from increase channel scale. In this study, a FFD-SF channel was developed for a large-scale fractionation, which has no flow stream splitters (‘splitter less’), and then was tested for optimum TP and FE by varying the sample concentration and the flow rates at the inlet and outlet of the channel. Polyurethane (PU) latex beads having two different size distribution (about 3~7 µm, and about 2~30 µm) were used for the test. The sample concentration was varied from 0.2 to 0.8% (wt/vol). The channel flow rate was varied from 70, 100, 120 and 160 mL/min. The fractionated particles were monitored by optical microscopy (OM). The sample recovery was determined by collecting the particles on a 0.1 µm membrane filter. Accumulation of relatively large micron sized particles in channel could be prevented by feeding carrier liquid. It was found that, in order to achieve effective TP, the concentration of sample should be at higher than 0.4%.

• Journal of Korean Society of Transportation
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• v.19 no.4
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• pp.19-33
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• 2001

In the developed countries, traffic noise is one of most serious problems faced by people's lives. So the importance of the traffic noise is quite well recognized by the infrastructure planners as well as the people. The traffic noise is valued in monetary terms in some countries and it is reflected in estimating the net present value or benefit/cost ratio. On the contrary, the effects of traffic noise are not reflected in the assessment of infrastructure in most cases in Korea. However, as the income level has been increasing, more people have been becoming to put more importance on their living conditions. The purpose of this paper is to estimate the value of traffic noise in the Seoul metropolitan area. The housing price were surveyed to use the quasi-hedonic price technique. By this way, two housing prices at the same floor level in different 128 complexes in the Seoul metropolitan area were surveyed. the actual traffic noise level was also measured. The differences of housing prices and noise levels were analyzed using the various types of regression models. The value is quite different by size of house. The value of large house is higher than that of small house. Since the income level of people in large house is higher than that in small house. it might be said that value of traffic noise for high income people is higher than that for low income people. Moreover, the increase of 1dB(A) noise affects the house price by about 0.3% in Seoul metropolitan area.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.1
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• pp.39-47
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• 2009

The importance of securing water resources and their efficient management has attracted more attention recently due to water deficit. In water budget analysis, however, evapotranspiration(${\lambda}E$) has been approximated as the residual in the water balance equation or estimated from empirical equations and assumptions. To minimize the uncertainties in these estimates, it is necessary to directly measure ${\lambda}E$. In this study, using the eddy covariance technique, we have measured ${\lambda}E$ in a mixed forest in the Seolmacheon catchment in Korea from September 2007 to December 2008. During the growing season(May-July), ${\lambda}E$ in this mixed forest averaged about $2.2\;mm\;d^{-1}$, whereas it was on average $0.5\;mm\;d^{-1}$ during the non-growing season in winter. The annual total ${\lambda}E$ in 2008 was $581\;mm\;y^{-1}$, which is about 1/3 of the annual precipitation of 1997 mm. Despite the differences in the amount and frequency of precipitation, the accumulated ${\lambda}E$ during the overlapping period(i.e., September to December) for 2007 and 2008 was both ${\sim}110$ mm, showing virtually no difference. The omega factor, which is a measure of decoupling between forest and the atmosphere, was on average 0.5, indicating that the contributions of equilibrium ${\lambda}E$ and imposed ${\lambda}E$ to the total ${\lambda}E$ were about the same. The results suggest that ${\lambda}E$ in this mixed forest was controlled by various factors such as net radiation, vapor pressure deficit, and canopy conductance. In this study, based on the direct measurements of ${\lambda}E$, we have quantified the relative contribution of ${\lambda}E$ in the water balance of a mixed forest in the Seolmacheon catchment. In combination with runoff data, the information on ${\lambda}E$ would greatly enhance the reliability of water budget analysis in this catchment.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.749-753
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• 2008

Proprioception defined it as the ability to detect, the spatial position or movement of joints using balance, power of the muscle, agility in the internal parts of the body. In existing study for improvement of proprioception, reaching task training provided a feedback; the assessment was not provided a feedback. But, this has problem that it can not guide a proprioception from situation with visual feedback. Virtual reality technique can solve the problem of way providing feedback during training. In this study, we developed proprioception training program using virtual reality and pilot study is performed. VR task were composed three modes. In mode 1, real-time movement of the body was provided using visual feedback. In mode 2, body position was provided using visual feedback when participant have specific response. And in mode 3, body position was not provided. VR task is performed five sessions at each mode and one session performed one by one a three target. In the result of this study, the moving time toward the target from mode 3 was smaller than the moving time toward the target from mode 1 (p= 0.001). The correlation was statistically significant between mode 2 and mode 3 while be offering visual feedback position of mode 2 1session. But, the correlation was not statistically significant between mode 2 and mode 3 after be offered visual feedback position of mode2 1session (p = 0.012). Training environment of mode 1 shows which training used visual feedback than proprioception. Mode2 can execute training of proprioception because first session acquires visual feedback by proprioception. The next study will be verification of the system for training or assessment by clinical experiment.

• Journal of Periodontal and Implant Science
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• v.26 no.3
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• pp.605-624
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• 1996

Various bonegraft materials and the technique of guided tissue regeneration have been used to regenerate lost periodontal tissue. Calcium sulfate has been known as a bone graft material because of good biocompatibility, rapid resorption and effective osteoinduction. It has been known that calcium sulfate works as a binder to stabilize the defect when it is used with synthetic graft materials. The effects on the regeneration of pericxiontal tissue were studied in dogs after grafting 3-wall intrabony defects with calcium carbonate and calcium sulfate and covering with calcium sulfate barrier. The 3-wall intrabony defectstdmm width, 4mm depth, 4mm length) were created in anterior area and treated with flap operation alone(contol group), with porous resorbable calcium carbonate graft alonetexperirnental group 1), with calcium sulfate graft alonetexperimental group 2) and with composite graft of 80% calcium carbonate and 20% calcium sulfate with calcium sulfate barriertexperimental group 3). Healing responses were histologically observed after 8 weeks and the results were as follows: 1. The alveolar bone formation was $0.59{\pm}0.19mm$ in the control group, $1.80{\pm}0.25mm$ in experimental group 1, $1.61{\pm}0.21mm$ in experimental group 2 and $1.94{\pm}0.11mm$ in experimental group 3 with statistically significant differences between control group and all experimental groups(P<0.05). There were statistically significant differences between experimental group 1 and group 2 (P<0.05). 2. The new cementum formation was $0.48{\pm}0.19mm$ in the control group. $1.72{\pm}0.26mm$ in experimental group 1, $1.43{\pm}0.17mm$ in experimental group 2, $1.89{\pm}0.15mm$ in experimental group 3 with statiscally significant differences between control group and all experimental groups (p<0.05). There were statistically significant differences between experimental group 1 and group 2, and between experimental group 2 and group 3(P<0.05). 3. The length of junctional epithelium was $1.61{\pm}0.20mm$ in the contol group, $0.95{\pm}0.06mm$ in experimental group 1, $1.34{\pm}0.16mm$ in experimental group 2, $1.08{\pm}0.11mm$ in experimental group 3 with statiscally significant differences between control group and experimental group 1. and btween control group and experimental group 3(p<0.05). There were statistically significant differences between experimental group 1 ,and group 2, and between experimental group 2 and group 3(P<0.05). 4. The connective tissue adhesion was $1.67{\pm}O.20mm$ in the control group, $1.33{\pm}0.24mm$ in experimental group 1. $1.23{\pm}0.16mm$ in experimental group 2, $1.08{\pm}0.14mm$ in experimental group 3 with statistically significant differences between control group and all experimental groups(p<0.05). There were nostatistically significant differences between all experimental groups. As a result, epithelial migration was not prevented when calcium sulfate was used alone, but new bone and cementum formation were enhanced. Epithelial migration was prevented and new bone and cementum formation were also enhanced when calcium carbonate was used alone and when both calcium carbonate and calcium sulfate were used.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.2
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• pp.169-181
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• 2007

Statement of problem: Titanium is well known as a proper metal for the dental restorations, because it has an excellent biocompatibility, resistance to corrosion, and mechanical property. However, adhesion between titanium and dental porcelains is related to the diffusion of oxygen to the reaction layers formed on cast-titanium surfaces during porcelain firing and those oxidized layers make the adhesion difficult to be formed. Many studies using mechanical, chemical and physical methods to enhance the titanium-ceramic adhesion have been actively performed. Purpose: This study meant to comparatively analyse the adhesion characteristics depending on different titanium surface coatings after coating the casts and wrought titanium surfaces with Au and TiN. Material and method: In this study, the titanium specimens (CP-Ti, Grade 2, Kobe still Co. Japan) were categorized into cast and wrought titanium. The wrought titanium was cast by using the MgO-based investment(Selevest CB, Selec). The cast and wrought titanium were treated with Au coating($ParaOne^{(R)}$., Gold Ion Sputter, Model PS-1200) and TiN coating(ATEC system, Korea) and the ultra low fusing dental porcelain was fused and fired onto the samples. Biaxial flection test was done on the fired samples and the porcelain was separated. The adhesion characteristics of porcelain and titanium after firing and the specimen surfaces before and after the porcelain fracture test were observed with SEM. The atomic percent of Si on all sample surfaces was comparatively analysed by EDS. In addition, the constituents of specimen surface layers after the porcelain fracture and the formed compound were evaluated by X-ray diffraction diagnosis. Result: The results of this study were obtained as follows : 1. The surface characteristics of cast and wrought titanium after surface treatment(Au, TiN, $Al_2O_3$ sandblasting) were similar and each cast and wrought titanium showed similar bonding characteristics. 2. Before and after the biaxial flection test, the highest atomic weight change of Si component was found in $Al_2O_3$ sandblasted wrought titanium(28.6at.% $\rightarrow$ 8.3at.%). On the other hand, the least change was seen in Au-Pd-In alloy(24.5at.% $\rightarrow$ 9.1at.%). 3. Much amount of Si components was uniformly distributed in Au and TiN coated titanium, but less amount of Si's was unevenly dispersed on Al2O3 sandblasting surfaces. 4. In X-ray diffraction diagnosis after porcelain debonding, we could see $Au_2Ti$ compound and TiN coating layers on Au and TiN coated surfaces and $TiO_2$, typical oxide of titanium, on all titanium surfaces. 5. Debonding of porcelain on cast and wrought titanium surface after the biaxial flection is considered as a result of adhesion deterioration between coating layers and titanium surfaces. We found that there are both adhesive failure and cohesive failure at the same time. Conclusion: These results showed that the titanium-ceramic adhesion could be improved by coating cast and wrought titanium surfaces with Au and TiN when making porcelain fused to metal crowns. In order to use porcelain fused to titanium clinically, it is considered that coating technique to enhance the bonding strength between coating kKlayers and titanium surfaces should be developed first.

• Investigative Magnetic Resonance Imaging
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• v.5 no.1
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• pp.57-65
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• 2001

Purpose : $T_2$-weighted half courier Echo Planar Imaging (T2HEPI) method is proposed to reduce measurement time of existing EPI by a factor of 2. In addition, high $T_2$ contrast is obtained for clinical applications. High resolution single-shot EPI images with $T_2$ contrast are obtained with $128{\times}128$ matrix size by the proposed method. Materials and methods : In order to reduce measurement time in EPI, half courier space is measured, and rest of half courier data is obtained by conjugate symmetric filling. Thus high resolution single shot EPI image with $128{\times}128$ matrix size is obtained with 64 echoes. By the arrangement of phase encoding gradients, high $T_2$ weighted images are obtained. The acquired data in k-space are shifted if there exists residual gradient field due to eddy current along phase encoding gradient, which results in a serious problem in the reconstructed image. The residual field is estimated by the correlation coefficient between the echo signal for dc and the corresponding reference data acquired during the pre-scan. Once the residual gradient field is properly estimated, it can be removed by the adjustment of initial phase encoding gradient field between $70^{\circ}$ and $180^{\circ}$ rf pulses. Results : The suggested T2EPl is implemented in a 1.0 Tela whole body MRI system. Experiments are done with the effective echo times of 72ms and 96ms with single shot acquisitions. High resolution($128{\times}128$) volunteer head images with high $T_2$ contrast are obtained in a single scan by the proposed method. Conclusion : Using the half courier technique, higher resolution EPI images are obtained with matrix size of $128{\times}128$ in a single scan. Furthermore $T_2$ contrast is controlled by the effective echo time. Since the suggested method can be implemented by software alone (pulse sequence and corresponding tuning and reconstruction algorithms) without addition of special hardware, it can be widely used in existing MRI systems.

• Journal of Internet Computing and Services
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• v.17 no.1
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• pp.101-107
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• 2016

Due to the recent advancement in digital imaging technology, development of intervention equipment has become generalize. Video arbitration procedure is a process to insert a tiny catheter and a guide wire in the body, so in order to enhance the effectiveness and safety of this treatment, the high-quality of x-ray of image should be used. However, the increasing of radiation has become the problem. Therefore, the studies to improve the performance of x-ray detectors are being actively processed. Moreover, this intervention is based on the reference of the angiographic imaging and 3D medical image processing. In this paper, we propose a guidance system to support this intervention. Through this intervention, it can solve the problem of the existing 2D medical images based vessel that has a formation of cerebrovascular disease, and guide the real-time tracking and optimal route to the target lesion by intervention catheter and guide wire tool. As a result, the system was completely composed for medical image acquisition unit and image processing unit as well as a display device. The experimental environment, guide services which are provided by the proposed system Brain Phantom (complete intracranial model with aneurysms, ref H+N-S-A-010) was taken with x-ray and testing. To generate a reference image based on the Laplacian algorithm for the image processing which derived from the cerebral blood vessel model was applied to DICOM by Volume ray casting technique. $A^*$ algorithm was used to provide the catheter with a guide wire tracking path. Finally, the result does show the location of the catheter and guide wire providing in the proposed system especially, it is expected to provide a useful guide for future intervention service.

• Journal of Preventive Medicine and Public Health
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• v.15 no.1
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• pp.167-177
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• 1982

This study was undertaken to observe relationships between patterns of feeding, supplementary-feeding and various maternal, family, and socioeconomic charactereistics in Hae Cheog Apartment area in Cheongdam-dong, Kangnamku, Seoul on July 2 to 12 in 1982. The results were based on a questionnaire from 179 mothers who have the last-born child under two years old. Results were as follows: 1) In socio-demographic characteristics, most of mothers were 25 to 30 years old and 52.0% of index children were under 6 months old. About 56.0% of families were the salaries and 47.0% of them earn over 500,000 won a month. 40.8% of mothers were college graduates and 81.6% of mothers had no occupation. 2) 89.4% of mothers received prenatal care in pregnancy of the index children and mothers who have delivered the child in medical institute were 88.3%. Mothers who recieved education of breast care and feeding technique through prenatal care were 22.4%, 31.8% respectively. 3) In the feeding method, 44.1% of mothers took the breast feeding, 24.0% of them chose the artificial feeding, and 20.7% of them chose the mixed feeding. Mothers who changed the-method from breast feeding to artificial feeding were 10.6% and only 0.6% of mothers changed from artificial feeding to breast feeding. 4) According to the questionnaire, 37 mothers have already finished lactation (no relation with. the beginning of weaning food). In breast feeding, one mother has lactated for $4{\sim}6$ months, one has lactated for $7{\sim}9$ months, four have lactated for $10{\sim}12$ months, and seven have. continued the lactation over 12 months. In artificial and mixed feeding, as the same phenomenon, most of mothers have lactated for more than 12 months. 5) The reasons for feeding method were as follows: In breast feeding, 64.6% of them took the method because they thought the breast milk nutrious, in artificial feeding, 34.9% of them chose it because they had occupation and in the mixed feeding, 67.6% of mothers took the method because of lack of their breast milk. In the case of changing the method from breast feeding to artificial feeding, 42.1% of them answered that they had to change the method because of lack of breast milk. 6) In most of cases, the 4th month was the proper period to begin the weaning food and 32.5% of breast feeding children and 27.6% of artificial feeding children began the weaning food in 4th month. After 4th month, there was no difference between breast feeding and artificial feeding in the beginning of weaning food. 7) In the matter of menstruation, 29.8% of mothers who had breast feeding started their menstruations in 3 months and the rest of them delayed until 12 months. 40% of mothers who had artificial feeding began to menstruate after 2 months and all the rest started within 5 months. 8) The birth interval between the index child and next new child (would-be-born): In breast feeding, the interval of $18{\sim}24$ months had a majority as 50.0%, and in the artificial feeding, the interval of over 24 months marked 66.7% of them. It was analyzed that the birth interval of artificial feeding was wider than that of breast feeding. 9) In the desirable number of children, the mothers who had breast feeding wanted two sons and two daughters as proper children. Those who want two children in disregard of the sex (son or daughter) were 89.3% of breast feeding, and 80.0% of artificial feeding respectively. Mothers who had breast feeding wanted two children rather than one child. 10) In the family planning practice, the rate of practice were 41.9% in breast feeding, and 58.1% in artificial feeding respectively. In the case of breast feeding, the using rate of family planning practice in men was higher than in women.

• Korean Security Journal
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• no.36
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• pp.177-200
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• 2013

As we enter a high industrial society that widens the gap between the rich and poor, demand for the security services has grown explosively. With the growth in quantitative expansion of security services, people have also placed increased requirements on more sophisticated and diversified security services. Consequently, market outlook for private security services industry is positive. However, Korea's private security services companies are experiencing difficulties in finding a direction to capture this new market opportunity due to their small sizes and lack of management-strategic thinking skills. Therefore, we intend to offer a direction of development for our private security services industry using a management-strategy theory and the Analytic Hierarchy Process(AHP), a structured decision-making method. A resource-based theory is one of the important management strategy theories. It explains that a company's overall performance is primarily determined by its competitive resources. Using this theory, we could analyze a company's unique resources and core competencies and set a strategic direction for the company accordingly. The usefulness and validity of this theory has been demonstrated as it has often been subject to empirical verification since 1990s. Based on this theory, we outlined a set of basic procedures to establish a management strategy for the private security services companies. We also used the AHP method to identify competitive resources, core competencies, and strategies from private security services companies in contrast with public companies. The AHP method is a technique that can be used in the decision making process by quantifying experts' knowledge and unstructured problems. This is a verified method that has been used in the management decision making in the corporate environment as well as for the various academic studies. In order to perform this method, we gathered data from 11 experts from academic, industrial, and research sectors and drew distinctive resources, competencies, and strategic direction for private security services companies vis-a-vis public organizations. Through this process, we came to the conclusion that private security services companies generally have intangible resources as their distinctive resources compared with public organization. Among those intangible resources, relational resources, customer information, and technologies were analyzed as important. In contrast, tangible resources such as equipment, funds, distribution channels are found to be relatively scarce. We also found the competencies in sales and marketing and new product development as core competencies. We chose a concentration strategy focusing on a particular market segment as a strategic direction considering these resources and competencies of private security services companies. A concentration strategy is the right fit for smaller companies as a strategy to allow them to focus all of their efforts on target customers in a single segment. Thus, private security services companies would face the important tasks such as developing a new market and appropriate products for such market segment and continuing marketing activities to manage their customers. Additionally, continuous recruitment is required to facilitate the effective use of human resources in order to strengthen their marketing competency in a long term.