• Tunnel and Underground Space
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• v.9 no.1
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• pp.27-35
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• 1999

The characteristics of heat conduction for the heat source boundary like an arch shape cavern are different from those for the semi-infinite or circular boundary which can be driven theoretically. A new form of transient heat conduction equation in rock mass around the arch shape cavern is evaluated with analyzing the pattern of the rock temperature distribution measured at the cold storage pilot plant. The new equation, which is driven by adopting a shape function, $SF=\sqrt{logx_0/log(x_0+x)}$ to the solution for a semi-infinite boundary, has the semi-radial form of temperature variation with distance. And, thermal properties of rock mass are estimated by comparing the rock temperature distributions by this equation with those by measurement. Thermal conductivity and specific heat of rock mass are estimated as giving the difference of 20~25% compared to those of laboratory scale. This difference seems to be caused by discontinuity like joint and water content in rock mass.

• Journal of Korean Society of Transportation
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• v.29 no.1
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• pp.113-123
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• 2011

The application of micro-simulation model has been extended farther with improvement of computer performance and development of complicated model. To make a micro-simulation model accurately replicate field traffic conditions, model calibration is very crucial. Studies on calibration of micro-simulation model have not been enough while lots of studies on calibration of macro-simulation model have been continued in our country. This paper presents an auto-calibration of parameter values in micro-simulation model(VISSIM) using genetic algorithm. RMSE(Root Mean Square Error) of collected volume on the urban expressway versus simulated volume is set as MOP(measure of performance) and objective function of optimization is set as to minimize the RMSE. Applying to urban expressway(Nae-bu circular) as a case study, it shows that RMSE of optimized parameter values decrease 60.4%($19.3{\longrightarrow}7.6$) compared to default parameter values and the proposed auto-calibration system is very effective.

• Journal of Periodontal and Implant Science
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• v.39 no.2
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• pp.167-176
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• 2009

Purpose: The purpose of this study is to histologically and histomorphometrically evaluate the effect of PLGA on bone regeneration compared with bone graft material. Methods: The experimental study was conducted in 10 rabbits with 2 different healing periods of 2 and 4 weeks. Following surgical exposure of the calvarium, 4 circular bone defects with a diameter of 4.6mm were formed. Rabbits were divided into control group, test groups I, and II. 10 defects assigned to the test group Ⅰ were grafted with Nu-oss and other 10 defects assigned to the test group II were grafted with PLGA. The rest of the defects were in the negative control group. At 2nd and 4th week after surgery, 10 rabbits were sacrificed through intracardiac perfusion and then specimens were obtained. Histological analysis was performed following staining with trichorme and transversal sectioning of the calvarial bone. Results: A group which used PLGA showed tissue reactions characterized by severe inflammation, rather than distinctive new bone formation. Conclusions: The present experimental investigations have failed to prove any beneficial effects of PLGA. PLGA used in this study exhibited foreign body reactions and a less favorable pattern of new bone formation in comparison to control group. Conclusion: PLGA did not function as scaffold. Further investigations of many types of micro PLGA that could improve its potential in GBR procedures are needed.

• The Journal of the Acoustical Society of Korea
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• v.14 no.2E
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• pp.73-86
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• 1995

The transducer section of the forward-looking ultrasound imaging catheter (FLUIC) consists of a circular piezoelectric element as a vibrator and a conical acoustic mirror as a perfect reflector. A small diameter piezoelectric transducer element is mounted on the side of a catheter's rotating shaft. The unique design of FLUIC provides the capability to form a two-dimensional image of a cross-section of vessel in front of the catheter, which is lacking in the present generation of intravascular ultrasound (IVUS) transducers, as well as a conventional side view image. The mirror configuration for the transducer section of the FLUIC is designed using an approximated ray tracing techniques. The diffraction transfer function approach [1] developed for the field prediction from primary sources is generalized and extended to predict the secondary diffraction characterstics from an acoustic mirror. The extended model is verified by simulation and experiment through a simple plane reflector and employed to analyzed the field characteristics of a FLUIC.

• Journal of Microbiology and Biotechnology
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• v.28 no.6
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• pp.987-996
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• 2018

Bacterial programmed cell death is regulated by the toxin-antitoxin (TA) system. YhaV (toxin) and Pr1F (antitoxin) have been recently identified as a type II TA system in Escherichia coli. YhaV homologs have conserved active residues within the C-terminus, and to characterize the function of this region, we purified native YhaV protein (without denaturing) and constructed YhaV proteins of varying lengths. Here, we report a new low-temperature method of purifying native YhaV, which is notable given the existing challenges of purifying this highly toxic protein. The secondary structures and thermostability of the purified native protein were characterized and no significant structural destruction was observed, suggesting that the observed inhibition of cell growth in vivo was not the result of structural protein damage. However, it has been reported that excessive levels of protein expression may result in protein misfolding and changes in cell growth and mRNA stability. To exclude this possibility, we used an [$^{35}S$]-methionine prokaryotic cell-free protein synthesis system in vitro in the presence of purified YhaV, and two C-terminal truncated forms of this protein (YhaV-L and YhaV-S). Our results suggest that the YhaV C-terminal region is essential for mRNA interferase activity, and the W143 or H154 residues may play an analogous role to Y87 of RelE.

• Journal of the Korean Society of Hazard Mitigation
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• v.3 no.2 s.9
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• pp.147-154
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• 2003

In this study, hydraulic characteristics around bridge piers were analyzed with and without collar through a hydraulic model experiment. The analysis of stage variation in front and back side of pier showed that collar installation did not function as obstacle to the stream flow. Little variation of water level between front and back sides of pier was observed before and after collar installation(0.2cm in front side and 0.1cm in back side of pier). Also, result that analyze velocity variation in front and back side of pier, lateral velocity(u) and transverse(v) before and after collar installation exhibited no alteration in the front and back side of pier. About 16.72% and 15.83% of vertical velocities(w) were reduced for the condition of y/d=0.33 in the front side of pier and y/d=0.67 in the back side of pier, respectively. This experimental results suggest that the collar installation around pier can minimize the local scouring depth by preventing the downflow that cause the pier scour.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.1
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• pp.37-48
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• 1990

The drag and heat transfer reduction phenomena and degradation effects of drag reducing polymer solutions which are known as the viscoelastic fluids are investigated experimentally for the turbulent circular tube flows. Two stainless steel tubes are used for the experimental flow loops. Aqueous solutions of Polyacrylamide Separan AP-273 with concentrations from 300 to 1000 wppm are used as working fluids. Flow loops are set up to measure the friction factors and heat transfer coefficients of test tubes in the once-through system and the recirculating flow system. Test tubes are heated by power supply directly to apply constant heat flux boundary conditions on the wall. Capillary tube viscometer and falling ball viscometer are used to measure the viscous characteristics of fluids and the characteristic relaxation time of a fluid is determined by the Powell-Eyring model. The order of magnidude of the thermal entrance length of a drag reducing polymer solution is close to the order of magnitude of the laminar entrance length of Newtonian fluids. Dimensionless heat transfer coefficients of the viscoelastic non-Newtonian fluids may be represented as a function of flow behavior index n and newly defined viscoelastic Graetz number. As degradation continues viscosity and the characteristic relaxation time of the testing fluids decrease and heat transfer coefficients increase. The characteristic relaxation time is used to define the Weissenberg number and variations of friction factors and heat transfer coefficients due to degradation are presented in terms of the Weissenberg number.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.3
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• pp.247-257
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• 2001

New methods are proposed for printing a full resolution image on a limited output device. The proposed algorithm uses a dot-pattern database that models overlapping phenomena among neighbor printing dots. To solve the problem of dot-overlap, the gray levels of dot-pattern sets were calculated using a circular dot-overlap model and then measured by a spectrometer. Thereafter, in order to improve the visual quality of the color dithering, the contrast sensitivity function of the human visual system was used. As a result, the optimal dot-pattern can be selected from the database. Consequently, the proposed algorithm can produce high quality images while using low-cost color devices.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• no.1
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• pp.89-101
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• 2001

The purpose of this study ins to verify the characteristic location of Byungyoung Castle, physical type, inside spatial organization, and the scheme of Byungyoung Castle. The study utilizes historic literature, ancient maps related to Byungyoung Castle, topographical and cadastral maps which were published under the rule of Japanese Imperialism Castle, topographical and cadastral maps which were published under the rule of Japanese Imperialism and the topographical maps which were made recently by National Geographic Institute with various scales. The methodology of the study is to interpret the contents from the historic literature on the site map. The methodology of the study is to interpret the contents from the historic literature on the site map. The result of the study is as follows; Byungyoung Castle does duty as a defensive base for the entire country and has a specific character of location that has the dual function of a mountain fortress for national defense and of a village fortress for the town. Byungyoung Castle has four gates on four sides and has a oval shape very close to a circular form. The road construction inside the castle is composed basically of a cross shape. Byungyoung is located in the northwest area of this major road system. The private houses that lie along the north-south road are build up at the core area of the lower level and the town market built up around the south gate becomes the heart of life for the people. Schematically, it has the same pattern as regular village fortress, in that the houses for the guests and the houses for the public office are arranged to the east and the west. It is considered that there is certain functional parallel between Byungyoug Castle and Ulsan castle because there are no facilities for sacrificial rites no institutional budding.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.1
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• pp.185-196
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• 1999

In this dissertation, a new off-line recognition system is proposed using a subgraph pattern, neural network. After thinning is applied to input characters, balance having a noise elimination function on location is performed. Then as the first step for recognition procedure, circular elements are extracted and recognized. From the subblock HT, space feature points such as endpoint, flex point, bridge point are extracted and a subgraph pattern is formed observing the relations among them. A region where vowel can exist is allocated and a candidate point of the vowel is extracted. Then, using the subgraph pattern dictionary, a vowel is recognized. A same method is applied to extract horizontal vowels and the vowel is recognized through a simple structural analysis. For verification of recognition subgraph in this paper, experiments are done with the most frequently used Myngjo font, Gothic font for printed characters and handwritten characters. In case of Gothic font, character recognition rate was 98.9%. For Myngjo font characters, the recognition rate was 98.2%. For handwritten characters, the recognition rate was 92.5%. The total recognition rate was 94.8% with mixed handwriting and printing characters for multi-font recognition.