• Journal of Korean Society of Steel Construction
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• v.17 no.3 s.76
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• pp.325-335
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• 2005

This study tackles the development of an improved detail of partially restrained CFT square column-to-beam connection and the evaluation of its mechanical behavior under monotonic loading. The connection is designed to strengthen shearing capacity at the bottom of the connection due to the ultimate behavior of PR-CC by its detail of the bottom connection and simplify the fabrication process. The suggested connection is the welded bottom beam flange connection(M-2) and is compared with the existing PR-CC of bolted seat angle connection(M-1). Two specimens were fabricated in actual size and tested under monotonic loading. Based on the test results, the welded bottom beam flange connection exhibited about 85% of the stiffness of steel beam. It was similar to the bolted seat angle connection and behaved as PR-CC. The specimen of the supposed connection type failed at the shear connection of web but was similar to the bolted seat angle connection until the failure. It obtained sufficient stiffness and capacity through the reinforcingsteel and the capacity and deformational ability equivalent to the full-plastic moment through the anchor inside the steel tube at the web connection. So, it can be said that the suggested connection exhibits sufficient ductile behavior.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.667-675
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• 2012

Flat plate are being used more in buildings requiring a high level of technical installations or in buildings needing changeable room arrangements during their life time such as office buildings. The main problem in flat plate is its weak resistance against a punching failure at its slab-column connections. Therefore, in this research, an experimental study on full-scale interior slab-column connection was performed. Three types of shear reinforcements were tested to prevent brittle punching shear failure that could lead to collapse of the structure. A series of four flat plate specimens including a specimen without shear reinforcement and three specimens with shear reinforcements were tested. The slabs were tested up to failure using monotonic vertical shear loading. The presences of the shear reinforcements substantially increased punching shear capacity and ductility of the interior slabcolumn connections. The test results showed that a slab that did not have enough bond length failed before shear reinforcement yielded due to anchorage slip. Also, FEM analyses were performed to study an effect of slab thickness and concrete compressive strength on the flat plate slab. The analytical study results were used to propose a method to calculate performance capacity of shear reinforcement in slab-column connection.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.13-24
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• 2020

A systematic approach to assess the safety of corrugated steel plate structures has not been established yet. Therefore, an improved safety assessment procedure was proposed in this study by considering the characteristics of corrugated steel plate structures in which the dead load of backfill soil is dominant and the live load effect is minimized. The proposed procedure can consider the combined effect of axial force and bending moment on the safety, based on the Soil-Culvert Interaction (SCI) method, and can differentiate the maintenance scheme according to the calculated plasticity index. There is also an advantage in enhancing the accuracy of assessment, utilizing the measured displacements. Furthermore, improved methods were proposed by discussing various ways for reasonably improving the proposed assessment procedure. The safety of an actual structure and a full-scale test specimen was assessed by applying the proposed procedure. The conventional assessment procedure significantly overestimated the load-carrying capacity, whereas the proposed procedure resulted in a reasonable level of safety. Therefore, the procedure proposed in this study is expected to contribute to the establishment of proper maintenance plan such as the quantitative condition assessment and strengthening of corrugated steel plate structure.

• Journal of Periodontal and Implant Science
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• v.40 no.1
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• pp.3-10
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• 2010

Purpose: Periodontal regenerative therapies for defects created by severe periodontitis are mainly focused on bone regeneration. Although cementum regeneration needs to be better understood, it is believed to play an important role in periodontal regeneration. The first step toward a full understanding of cementum regeneration is to compare repaired cementum to pristine cementum. This study, which used histological techniques, was designed to focus on cementum regeneration and to compare pristine cementum to repaired cementum after surgical procedures with 8 and 24 week healing periods in a canine model. Methods: Buccal and lingual mucoperiosteal flaps of 10 beagle dogs were surgically reflected to create critical-sized defects. Intrabony one-wall defects, of which dimension is 4 mm width and 5 mm depth, were made at the distal aspect of mandibular second premolars and the mesial aspect of mandibular fourth premolars in the right and left jaw quadrants. Animals were sacrificed after 8 and 24 weeks post-surgery for histological specimen preparation and histometric analysis. Results: The repaired cementum was composed mostly of acellular cementum and cellular mixed fiber cementum and was thicker in the apical area than in the coronal area. The acellular cementum of the supracrestal area appeared to be amorphous. The newly formed cellular cementum was partially detached from the underlying circumpulpal dentin, which implied a weak attachment between new cementum and dentin, and this split was observed to a lesser extent in the 24 week group than in the 8 week group. The vertical height of the repaired cementum was greater in the 24 week group than in the 8 week group. Conclusions: Within the limitations of this study, we can conclude that repaired cementum after root planing was mainly acellular cementum and cementum tissue that matured to a shape similar to pristine cementum as the healing progressed from 8 to 24 weeks.

• Journal of the Korea Concrete Institute
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• v.13 no.6
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• pp.568-574
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• 2001

From measured responses of concrete three-point bend tests, the average values of the responses have been calculated. The fracture behavior of continuously propagating concrete crack has been analyzed from the average responses. The experimental parameters of this study were the initial notch sizes of 25.4㎜ and 6.4 ㎜ and the processing times of 2,000 sec. and 20 sec . The different notch sizes were used for the effects of the size of fracture process zone and specimen geometry, and the processing times for those of initial creep. However the load-point displacement rate in this study did not affect the experimental responses seriously. The average loads were calculated from the average external work of a series of tests, and average crack lengths were determined by using strain gages. Before the peak load, the resistance curve could be determined from the size of fracture process zone, but unstable crack propagation of 88㎜ occurred at the load-point displacement of 0.088∼0.154㎜ after the peak load. The average fracture energy density G$\_$F/$\^$ave/ = 115 N/m occurred during the unstable crack propagation. The fracture process zones were fully developed at the crack length of 111㎜, and the sizes of fracture process zone for initial notches of 25.4㎜ and 6.4㎜ were 86㎜ and 105㎜, respectively. Average fracture energy densities of the resistance curves after full development of fracture process zone were 229 N/m for the initial notch of 25.4㎜ and 284 N/m for 6.4㎜. The values were more than twice of G$\_$F/$\^$ave/.

• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.635-643
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• 2004

In this study, the tensile strength of 321 full-sized grout-filled splice steeve specimens were compared and analyzed in order to afford the data for a reasonable and economical design of this system. The experimental variables analyzed in this study were embedment length of reinforcing bars, compressive strength of grout, sleeve geometry, loading pattern and final failure mode of specimen. Following main conclusions are obtained : 1) The strength of grout-filled splice sleeve tends to be improved with increasing compressive strength of grout and embedment length of reinforcing bars. Specially this tendency appears apparent in specimens of bond failure rather than rebar failure. 2) The results of this study show that the sleeve geometry have influence on the bond strength of grout-filled splice sleeve. 3) The grout-filled splice sleeve of bond failure don't show the difference of tensile strength according to size of rebar. 4) It is verified that the tensile strength required in ACI and domestic code is retained either when the compressive strength of grout over 70 MPa is used with embedment length of reinforcing bars over 4.5d or when the compressive strength of grout over 80 MPa is used with embedment length of rebars over 3.9d. 5) It is verified that the tensile strength required in AIJ code is retained in case when the embedment length of reinforcing bars is 0.8 times the rebar diameter longer than in ACI code.

• Clinics in Shoulder and Elbow
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• v.15 no.2
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• pp.138-142
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• 2012

Pigmented villonodular synovitis (PVNS) is a rare benign proliferative disorder that results in villous hyperplasia and nodule formation in the synovium, tendon sheath and bursa. That most commonly affects the knee and the hip joint in adult. PVNS of the hand, the wrist, the shoulder and the elbow is rare and that of the elbow in children is particularly rarer. An eight-year-old boy had his left elbow pain and a lesion like benign bone tumor in the left fossa olecrani on plain x-ray. During the operation, abnormal synovial hyperplasia in his left elbow joint led us to diagnose PVNS. Therefore, open curettage of the lesion and radical synovectomy was performed. The specimen of the synovectomized tissue revealed PVNS. The left elbow pain subsided after the operation and the child restored a full range of motion of his left elbow. We reported this rare case of PVNS in a child's elbow joint mimicking the bone tumor together with a review of the literature.

• Korea Journal of Hospital Management
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• v.5 no.1
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• pp.129-155
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• 2000

This empirical study, activity-based costing, a newly introduced approach that has proved to be an improvement over the conventional costing system in product or service costing, is applied at department of clinical pathology in K university hospital. The study subjects were 233 test procedures done in clinical laboratory of K university hospital. Activity analysis was done by interview, questionnaires, and time study, and the amount of resources consumed by each activity and their costs are then traced and applied to the laboratory tests. The main purpose of this study were to compare the test costs of activity-bases costing with those of conventional costing, and test fees of medical insurance, and to provide accurate cost informations for the decision makers of hospital. The major findings of this study were as belows. 1. The cost drivers for application of activity-based costing at clinical laboratory were cases of sample collection, case of specimen, cases of test, and volume-related allocation bases such as direct labor hours and total revenue of each test. 2. The profits of each clinical laboratory fields analyzed by conventional costing were different from the profits analyzed by activity-based costing, especially in the field of Urinalysis(approximately over estimated 750%). 3. The standard full costs by conventional costing were quite different from the costs computed by using activity-based costing, and the difference is most significant with the tests of long labor time. 4. From the comparison between costs computed by using activity-based costing and medical insurance fees, some test fees were significantly lower than the costs, especially in the non-automated fields. As described in this study, activity-based costing provides more accurate cost information than does conventional costing system. The former approach is especially important in the health care industry including hospitals in which planning and controlling the costs services provided are the key to maintaining a healthy financial status for the organization. Despite the contribution of activity-based costing the economic as well as technical feasibilities of implementing such a cost accounting system in an organization must be evaluated. In the development of activity-based costing systems, an activity analysis has to be conducted to identify activities that consume resources. This involves a detailed study of the organization's logistics and accounting information systems, and it is an expensive project in itself. Besides, it can be quite difficult and time consuming to identify and trace resource consumption to a specific activity. Thus the activity-based costing system should be implemented only when the decrease in cost of error far exceeds the increase in cost of measurement. By combining activity-based costing with standard costing, health care administrators can better plan and control the costs of health services provided while ensuring that the organization's bottom line is healthy.

• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.185-194
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• 2012

The purpose of this contribution is to develop the framework of a methodology for identifying potential errors in georeferencing and in an application of it using specimens of Ox-Knee, Achyranthes bidentata Blume in Korea. At infraspecific level, uncertainty of identification showed that 41% of A. bidentata var. japonica and 28% of var. bidentata were misidentified, suggesting that the uncertainty level was independent of the reliability of experts' identification. For georeference specimen records, 71 specimens out of total 303 were selected and utilized as occurrence data: Uncertainty was 32.4 km at maximum and was 0.1297 km at minimum (mean = 4,055 m, s.d. = 5,772 m). Var. japonica is common throughout most of the southeastern Korea and west coastal areas, while var. bidentata has been found as far north as Gyeonggi and Gangwon provinces. We modelled the potential distribution of two varieties using Bioclim approach in Korea based on several environmental factors. Our results indicated the most important region for var. japonica lies the west coast ranges and southern area, while for Chungcheongnam-do of potential high diversity occurs for var. bidentata. This study shows that the major factors to determine the distribution patterns of two varieties were thermal factors, rather than precipitation. The Bioclim model using geocode and georeferencing data makes the information increasingly useful and reliable. To improve data quality, it requires full management from data collection to final databases including data cleaning.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.751-757
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• 2003

Rapid densification of a SiC-30 wt% TiC powder with additive 10 wt% A1$_2$O$_3$-Y$_2$O$_3$-CaO was conducted by Spark Plasma Sintering(SPS). The fully-densified materials can be obtain through the SPS process with very fast heating rate and short holding time. In the present work, the heating rate and applied pressure were kept to be $100^{\circ}C$/min and 40 MPa, while sintering temperature varied from $1600^{\circ}C$ to $1800^{\circ}C$ for 10 min. The full densification of SiC-30 wt% TiC composites with the addition of $Al_2$O$_3$, $Y_2$O$_3$ and CaO was achieved at the temperature above $1700^{\circ}C$ by spark plasma sintering. The XRD found that 3C-SiC and TiC were maintained the entire SPS process temperature, without phase transformation of SiC and formation of YAG phase to $1800^{\circ}C$. The microstructures of the rapidly densified SiC-30 wt% TiC composites consisted of smaller equiaxed SiC grains and larger TiC grains. The biaxial strength of 635.2 MPa and fracture toughness of 6.12 MPaㆍ$m^{1/2}$ were found for the specimen prepared at $1750^{\circ}C$.