• The Korean Journal of Ecology
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• v.22 no.1
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• pp.13-19
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• 1999

To investigate and compare the effects of air pollution near Seoul on soil ion, plant nutrient contents and plant growth, 14 Quercus mongolica forests were studied from Mt. Namsan in Seoul to Mt. Maebongsan in Kangwon-Do along the line transect. Soil pH values decreased as approached to Seoul. Concentrations of basic cations such as exchangeable Ca/sup 2+/, Mg/sup 2+/ and Na/sup +/ and effective cation exchange capacity(ECEC) in forest soil decreased as approached to Seoul. Ca/sup 2+/ and Mg/sup 2+/ contents in l-year-old Q. mongolica twigs decreased, but their K/sup +/ and Na/sup +/ contents increased as approached to Seoul. Ca/sup 2+/ contents in l-year-old Q. mongolica leaves decreased, but their K/sup +/ and Mg/sup 2+/ contents increased as approached to Seoul. Length of l-year-old twigs generally decreased near Seoul. Tree-ring analyses of Q. mongolica trees in Mt. Namsan and Mt. Yebongsan showed that mean tree-ring width in Mt. Namsan was narrower than that of Mt. Yebongsan from early 1970's to late 1980's.

• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.231-236
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• 2008

Purpose: The treatment of gingival recessions is needed to reduce root sensitivity and improve esthetical satisfaction. Several surgical techniques have been proposed to achieve these goals. The use of connective tissue grafts has made esthetic root coverage a predictable procedure. Numerous clinical studies have represented that using connective tissue grafts to cover exposed root surface showed high success rates. This is a case report which demonstrates the technique to obtain root coverage of a buccal recession defect. Materials and Methods: A 35-year-old patient with a high level of oral hygiene was selected for the study. This patient had one Class I Miller recession defect in the mandible. A coronally advanced flap in combination with the connective tissue graft was chosen for the treatment. After surgery, the patient was told to visit the hospital once a week for his oral management and professional prophylaxis. The depth of initial recession was 4.0 mm. Result: After three months, it reduced to 0.0 mm, and the average recession reduction was 4.0 mm. The average root coverage was 100%. Conclusion: The connective tissue graft is both effective and predictable way to produce root coverage in increasing the width of CAL and KT of various adjacent gingival recessions.

• The Journal of the Korean dental association
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• v.55 no.11
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• pp.766-776
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• 2017

This clinical study was conducted to evaluate the clinical effects of a concave neck of external connection type implant fixture designed for platform switching on the peri-implant tissue responses. Two types of implants with different neck designs were implanted in 20 patients. For the experimental group, the bioseal(BS) implant fixtures with 's' shaped concave profile on the neck were used, and non-bioseal(NBS) implant fixtures with a straight profile on the neck were used as control(Total of 40 implants, NBS: n = 19, BS: n=21). During the one-year period after implant placement, implant survival rate, marginal bone resorption, bleeding, plaque, and complications were evaluated. The survival rate of NBS and BS group was 94.74% and 90.48%, respectively. There was no significant difference on marginal bone resorption, bleeding and plaque between the two groups (P>.05). Within the limits of the present study, implants with a concave neck design showed similar clinical results to implants with a straight neck design on the peri-implant tissue responses. Longitudinal clinical studies are necessary to confirm more effective clinical results.

• Korean Journal of Plant Resources
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• v.23 no.3
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• pp.228-232
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• 2010

The present study was carried out to elucidate the effect of girdling on the quality and harvest date of the 'Shigyoku' grapes. Among girdled vines, the interval from full bloom to harvest date was 77 days; this was as much as seven days shorter in vines receiving a 20% girdling treatment. With regards to fruit characteristics, significant differences were observed in cluster length, berry number, and berry weight in vines that received girdling treatments. There were also significant differences in cluster weight; 468.2 g, 491.6 g and 504.9 g in the control group, 10% girdling group, and 20% girdling group, respectively. Thus, the use of girdling treatments is an effective approach to increasing cluster weight by 5% in the 10% girdling treatment and 8% in the 20% girdling treatment. The 10% girdling treatment showed significant difference in terms of titrable acidity; in fact, the overall titrable acidity was relatively high among all the girdling treatments. The concentration of anthocyanin increased in 20% girdling treatment, but there were no significant differences in anthocyanin concentration among girdling treatments. Berry color developed rapidly in vines that received girdling treatment.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.2
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• pp.116-126
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• 2009

The use of short implants has been accepted risky from biomechanical point of view. However, short implants appear to be a long term viable solution according to recent clinical reports. The purpose of this study was to investigate the effect of different diameter and length of implant size to the different type of bone on the load distribution pattern. Stress analysis was performed using 3-dimensional finite element analysis(3D-FEA). A three-dimensional linear elastic model was generated. All implants modeled were of the various diameter(${\phi}4.0$, 4.5, 5.0 and 6.0 mm) and varied in length, at 7.0, 8.5 and 10.0 mm. Each implant was modeled with a titanium abutment screw and abutment. The implants were seated in a supporting D2 and D4 bone structure consisting of cortical and cancellous bone. An amount of 100 N occlusal load of vertical and $30^{\circ}$ angle to axis of implant and to buccolingual plane were applied. As a result, the maximum equivalent stress of D2 and D4 bones has been concentrated upper region of cortical bone. As the width of implant is increased, the equivalent stress is decreased in cancellous bone and stress was more homogeneously distributed along the implants in all types of bone. The short implant of diameter 5.0mm, 6.0mm showed effective stress distribution in D2 and D4 bone. The oblique force of 100N generated more concentrated stress on the D2 cortical bone. Within the limitations of this study, the use of short implant may offer a predictable treatment method in the vertically restricted sites.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.9
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• pp.28-43
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• 1999

In this paper, we present a gridless router for MultiChip Modules (MCM). Because our router uses corner stitching data structures, not a routing grid, to represent the routings status, it allows arbitrary location of pins, and routes variable-width wires, without a considerable waste of area from bulky vias. A routing speed is a very important factor because a gridless routing approach is known its computation is hard and complex, and MCM routing problem has so large routing area and layers. Our router completes the routing faster than the most of previously reported grid-based routers, with comparable routing result, by using SEGRAs routing algorithm whose very fast speed is proved, and the characteristics of the effective data structure.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.3
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• pp.45-54
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• 2004

Microwave characteristics of ridge type CPW traveling-wave(TW) electroabsorption modulator and photodetector are affected by the thickness of intrinsic layer, width of guiding layer, and the separation of signal and ground electrodes. These factors are determined effective index of microwave and characteristic impedance due to changing of capacitance(C) and inductance(L) of device. However, conventional equivalent circuit of TW-structure is approximated to microstrip and CPW transmission line by distribution of electric and magnetic fields, respectively. In this paper, we analyzed microwave characteristics of TW-structure and found more accurate value of C and L by using finite difference time domain (FDTD) method. These values are adopted circuit element of equivalent circuit. Microwave characteristics obtained by the FDTD and equivalent circuit model show good agreement.

• Korean Journal of Agricultural Science
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• v.37 no.2
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• pp.309-314
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• 2010

Bale is an operation of collecting livestock feed materials from field crop residue, and mechanization demand on the operation has been increased. Bailers imported from foreign countries such as Japan and European countries have been used, but those models showed improper performance in Korean situations. In recent years, a steel-roller type round baler attachable to medium size tractors(40 to 60 HP) for effective bale operation in Korea was developed. This study was conducted to evaluate field performance of the baler. For proper baling operation, engine speed was greater than 1,800rpm, average traction force and PTO torque were about 4kN and in a range of 380-671Nm, and maximum values were about 7kN and 3,000Nm, respectively. Performance evaluation tests for sudan grass, rice straw, and blue barley showed that field capacity was 0.59ha/h for blue barley and 0.99ha/h for sudan grass and rice straw. Bale weight, diameter, width, and bulk density were in ranges of 176.1~418.4kg, 1.07~1.12m, 1.02~1.04m, and 175.3~454.1kg/$m^3$. Noise sound level during the baling operation was 4dB greater than idle operation condition, which was considered to be ignorant.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.73-80
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• 2010

Wind-induced vibration is one of the important structural design factors for serviceability of tall buildings. In order to evaluate the reliable wind-loads and wind induced-vibration, it is necessary to obtain the exact natural period of buildings. The discrepancy in the natural period estimation often results in the overestimation of wind loads. In this study, the effectiveness of lateral stiffness estimation method for tall buildings with flat plate system is evaluated. For this purposed, the results of finite element analysis of three recently constructed buildings are compared with those obtained from field measurement. For the analysis, factors affecting on the lateral resistance such as cracked stiffness of vertical members, elastic modulus of concrete, effective slab width, and cracked stiffness of link beam are considered. Form the results, it is found that the use of non-cracked stiffness and application of dynamic modulus of elasticity rather than initial secant modulus yields closer analysis result to the as-built period.

• Journal of Korean Association for Spatial Structures
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• v.7 no.1 s.23
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• pp.63-70
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• 2007

To improve the land use of urban, Construction of the circular steel column is required recently. The circular steel columns have a advantage for improving a load carrying rapacity as wall as reducing a effective section area. However, the circular steel columns under service load, such as earthquake, shows a tendency to cause local buckling and large deformation. To prevent these phenomena, use of longitudinal stiffeners is considered. The application of longitudinal stiffeners at the circular steel columns is expected to increase a load carrying capacity, buckling strength and seismic performance of circular steel column. However, increasing the loading carving rapacity of buckling which constructed the longitudinal stiffeners, was not investigated yet. Therefore it needs study on effect of longitudinal stiffener in pipe-section steel pier. In this study, the load rallying capacity of buckling of steel pier was investigated by using elastic-plastic finite element analysis considered geometrical and material non-linearity. Also, this study investigated the effect of longitudinal stiffeners on loading carrying capacity of buckling and the relationship between width and thickness of longitudinal stiffeners. And also, a Influence of longitudinal stiffeners on seismic performance of circular steel columns was investigated by numerical analysis