• Journal of Periodontal and Implant Science
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• v.38 no.1
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• pp.23-30
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• 2008

Purpose: The purpose of this study was to investigate the incidence of curet fracture and its contributing factors. Material and Methods: Fifty-eight periodontal curets which were broken during periodontal treatment in Kangnung National University Dental Hospital for 1 year were used as study materials. The blade thickness of new curets and broken ones was measured using a digital micrometer. Types of treatment procedures, clinical experience of operators, point of breakage, and method of removal of broken fragments were recorded for each broken curet. Results: The incidence of curet fracture in root planing (16.4 curets per 1,000 procedures) was higher than those in flap surgery (7.5) or supragingival scaling (2.7). No curet was broken during supportive periodontal treatment. The incidence of fracture did not seem to be related with clinical experience of operators. The most frequent breakage point of the curets were upper 1/3 of blades. Fifty-six of 58 broken fragments were removed by non-surgical methods. Two broken tips which could not removed non-surgically were left in the pockets, and proved to be removed spontaneously 1 week later. Conclusion: Root planing showed higher incidence of curet fracture than any other type of periodontal treatment. Most of the fractured fragments were removed by non-surgical method. Further study is needed to develop methods of removal of the fragments which can not be removed non-surgically.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.2
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• pp.190-199
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• 2014

In the last years, fault problem in power electronics has been more and more investigated both from theoretical and practical point of view. The fault problem can cause equipment failure, data and economical losses. And the analyze system require to ensure fault problem and also rectify failures. The current errors on these faults are applied for identified type of faults. This paper presents technique to detection and identification faults in three-phase voltage source inverter (VSI) by using time-frequency distribution (TFD). TFD capable represent time frequency representation (TFR) in temporal and spectral information. Based on TFR, signal parameters are calculated such as instantaneous average current, instantaneous root mean square current, instantaneous fundamental root mean square current and, instantaneous total current waveform distortion. From on results, the detection of VSI faults could be determined based on characteristic of parameter estimation. And also concluded that the fault detection is capable of identifying the type of inverter fault and can reduce cost maintenance.

• Journal of Plant Biology
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• v.14 no.4
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• pp.5-13
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• 1971

Pot and paddy field tests were conducted to study red discoloration of rice var. IR 667 leaves with reference to the leading Korean native variety Jinhung and Paldal, with the following results: 1. Minor elements such as Mn, Fe, B, Al, Ca and Si had no influence on the discoloration, but a supply of various soluble nitrogen compounds completely restricted it. The more prosperous the growth of IR 667 with nitrogen, the more severe the discoloration appears when nitrogen absorptin becomes limited. 2. Chlorotic pigments extracted from both IR 667 and Jinhung were compared spectrophotometrically, and found to have different spectral peaks. IR 667 had peak closer to red than Jinhung, indicating the characteristic of the variety. IR 667 was observed to be more sensitive to nitrogen deficiency than Jinhung or the other japonica variety. 3. It was concluded that all the factors limiting nitrogen supply for IR 667 growth, such as low nitrogen application, restriction of root respiration (low temperature, poor drainage, toxic gases or substances in the root zone, etc.) and pest injuries, would result in the appearance of the so-called red discoloration, because of the reduction in nitrogen uptake. Since, the discoloration of IR 667 is varietal characteristic when grown in Korea, control of it may be beneficial cultural practice in increasing grain yield, although the increased succeptibility to pests and a drop in the rate of maturity due to relatively high nitrogen level in the leaves may result in an unexpected drop in yield. It is anticipated that further exploration conducted from practical point of view will establish the relatioknships between the extent of red discoloration, nitrogen availability and grain yield in IR 667.

• Archives of Reconstructive Microsurgery
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• v.10 no.1
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• pp.7-11
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• 2001

Purpose : To evaluate the neurologic abnormalities in the donor limb after contralateral C7 transfer in brachial plexus injury. Materials and Methods : From August 1996 to December 1999, five patients with brachial plexus injury were treated with contralateral C7 nerve root transfer. The average follow up was 16 months(range, 5 to 36 months). The clinical findings were assessed using the British Medical Research Council Grading System, and also measured grip power, pinch power of hand and two point discrimination of the fingers. Results : We had no difference in shoulder abduction and elbow flexion after contralateral C7 transfer. The grip and pinch strength were recovered within 4weeks. Sensory loss occurred in all patients and was noted to be more severe on index and middle finger. Four patients recovered within 2 weeks, one continued till one year. Subjective numbness and pain on percussion minimally persisted until last follow-up. Conclusion : The division of the C7 nerve root resulted in minimal and temporary functional deficit in the donor upper limb.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.2
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• pp.300-307
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• 2002

Partial penetration welding joint is defined as groove welds welded from one side, without steel backing or groove welds welded from both sides but without back gouging. So it has an unwelded portion at the root of the weld. Study of partial penetration weldment fracture behavior includes residual stress analysis and fracture analysis. The J-integral loses its path independency in residual stress field. Therefore, it is necessary to introduce a new J-integral, J, which is defined including the effect of plastic deformation and thermal strain. In this study, theoretical formulation and program were developed for the evaluation of J-integral for the crack tip located in the weldment. Evaluations of fracture behavior were performed for partial penetration multi-pass weldment of 25.4mm thick plate by J-integral. From a point of fracture in partial penetration multi-pass welding, it seemed to be better to control root face smaller than 6.35mm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.92-98
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• 2002

In this study, maximum launch range and F-pole are evaluated and analyzed for the semi-active radar missile concerning various launch condition, performance limitation and target maneuvers. Furthermore, general evasion maneuvers are considered when shooter approaches to target with head-on conditions. A point-mass target, shooter and missile model is used including aircraft and missile dynamics. More realistic missile motion simulation is conducted using aerodynamic performance data, geometry, performance limitation, radar seeker performance and so on. Maximum launch range, which is the distance for intercept satisfying target and missile motion and performance, is evaluated using root finding method. F-pole, which is the distance between target and shooter when intercept is completed, is evaluated assuming that shooter maneuvers through pursuit guidance to target.

• Journal of Applied Biological Chemistry
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• v.49 no.4
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• pp.171-175
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• 2006

Chitin compost and broth were used to suppress club root. Individual cabbage seedlings were transplanted into pots(3500 ml) containing a mixture of 3% chitin compost and 50 ml of chitin broth (T1) or the same quantity control compost and control compost broth(T2). The media in each pot was then infected with Plasmodiophora brassicae. Samples were taken at 6, 7 and 8 weeks after transplanting. The population of chitinase producing bacteria in T1 was consistently larger than that observed in T2. Chitinase activity in the T1 rhizosphere was two-fold greater than that of T2 at each time point observed. Shoot dry weight, leaf number and leaf area in T1 were enhanced 20%, 10% and 12% relative to those seen in T2, respectively. The disease index and root mortality at 8 weeks after transplanting were reduced by 50% and 25% in T1 compared to T2, respectively. Results presented in this study are strongly indicative that chitin compost and broth suppress clubroot in Chinese cabbage.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.6
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• pp.40-47
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• 2004

The influence of heat input on fracture toughness was investigated in SAW weldments, which were prepared at two different welding conditions in API 2W Gr.50 and EN10225 5420. By examining the fracture initiation point, refined areas(ICHAZ and SCHAZ) in weld metal was identified as local brittle zone, in which M-A constituents and coarsed grain size were observed. Impact values showed the most significant difference at root portion, and CTOD transition temperature was related with impact values obtained at root portion. Hardness values in refined area were less than columnar microstructure about 20 HV5.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.5
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• pp.123-128
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• 2011

In this paper, we design the CA-CFAR processor using a root-square approximation approach and a fixed-point operation to improve hardware complexity and reduce computational effort. We also propose CA-CFAR processor with multi-window, which is capable of concurrent parallel processing. The proposed architecture is synthesized and implemented into the FPGA and the performance is compared with the conventional processor designed by root-square libarary licensed by FPGA corporation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1813-1819
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• 2001

Partial penetration welding Joint defines that groove welds without steel backing, welded from on side, and groove weeds welded from both sides but without back gouging, that is. it has an unwelded portion at the root of the weld. In this study we analysed fur residual stress and displacement distribution on partial penetration welding condition of thick plate metal. For 25.4mm thick plate, theoretical residual stress and displacement analysis by finite element method using ABAQUS was carried out and compared with the experimental result using hole-drilling method. In results of the condition of partial penetration, it appeared that longitudinal stress at welding area was a little difference and transverse stress did not have any effect by partial penetration multi-pass welding. From a point of welding distortion in partial penetration multi-pass welding, it seemed to be better to control root face smaller than 6.35mm.