• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.1
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• pp.1-5
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• 2010

Acoustic emission(AE) has emerged as a powerful nondestructive tool to detect or monitor preexisting defects and leaks in the vessel structures. A Bragg grating based acoustic emission sensor system is developed. Various type of fiber Bragg grating sensor including the variable length of sensing part was fabricated and prototype sensor system was tested by using PZT pulser and pencil lead break sources. Two types of sensor attachment were used. First, the fiber Bragg grating sensor was attached fully to the surface using bonding agent. Second one is that one part of fiber was attached to the surface partly by bonding and the other part of fiber will be act as a cantilever. That is, the resonant frequency of the fiber Bragg grating sensor will depend on the length of sensing part. The final goal of the sensor system is to provide on-line monitoring of cracks or leaks in reactor vessel head penetration of nuclear power plants.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1047-1052
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• 2012

Primary water stress corrosion cracking (PWSCC) instances have been reported in the Alloy 600 reactor pressure vessel head penetration nozzle and the Alloy 82/182 dissimilar metal butt weld nozzle in several PWRs. Therefore, in-service inspection programs have been adopted worldwide to prevent failure at the weld region. If a PWSCC is observed at the dissimilar metal weld region during inspection, its structural integrity should be evaluated; however, this requires considerable time and effort, and this might lead to a decrease in the plant utilization coefficient. To prevent this, KHNP-CRI have established integrity assessment criteria and developed a computer program for the fast evaluation and judgment of PWSCC. In this paper, the results and current status of the same are presented. Through this study, criteria for the structural integrity evaluation of PWSCC have been established, and a computer program has been developed to realize technical means for the evaluation of PWSCC structural integrity.

• Composites Research
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• v.35 no.6
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• pp.469-476
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• 2022

In this paper, the microwave absorbing characteristics after the impact of the radar-absorbing structure (RAS) consisting of periodic pattern sheet (PPS) and glass fiber-reinforced plastic (GFRP) were experimentally investigated. The fabricated RAS effectively absorbed the microwave in the X-band (8.2-12.4 GHz). In order to induce the damage to the RAS, a low-velocity impact test with various impact energy of 15, 40, and 60 J was conducted. Afterward, the impact damage was observed by using visual inspection, non-destructive test, and image processing method. Moreover, the absorbing performance of intact and damaged RAS was measured by the free-space measurement system. The experiment results revealed that the delamination damage from the impact energy of 15 J did not considerably affect the microwave absorbing performance of the RAS. However, fiber breakage and penetration damage with a relatively large damaged area were occuured when the impact energy was increased up to 40 J and 60 J, and these failures significantly degraded the microwave absorbing characteristics of the RAS.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.90-93
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• 2005

경상남도 합천군과 창녕군 생활용수 지하수 관정 개발시 지하수 굴착공종으로부터 얻어진 구간별 지층자료와 대수층 수질 자료를 획득하여 이용하는 방법을 연구하였다. 지층정보를 파악하기 위하여 지하수공 굴착심도 10m마다 슬라임을 채취하였으며, 대수층 관통시에 지하수 시료를 구간별로 채수하여 전기전도도 및 수질시료를 분석하였다. 경도가 높은 지역의 경우, 음용수 수질기준치에 적합한 지하수를 개발하기 위해서 대수층별 전기전도도를 분석측정하여 경도를 간접적으로 파악함으로써 지하수 굴착심도 결정에 이용하였다. 그리고 대수층 구간별 불소 농도를 파악하였으며, 불소 농도가 높은 대수층 구간에서는 하부대수층 메움 등을 실시하였다. 대수층의 수질검사결과에서 기준치를 초과하는 우려 인자들(불소, 경도, 증발잔류물, 질산성 질소, 철, 알루미늄, 아연 등)에 대한 수질기준 초과 가능성을 대비한 양수시험 모니터링을 설계함으로써 지하수공의 수질 특성 파악이 가능하였다. 양수시험과정에서 탁도가 시간에 따라 기준치 이하까지 감소하는 일반적인 경향과 기준치 이상에서 더 이상 감소하지 않는 경향에 대한 원인을 분석할 수 있었다.

• Journal of the Korean Orthopaedic Association
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• v.55 no.5
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• pp.431-435
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• 2020

Pseudoaneurysm which is usually caused by high energy trauma or penetrating injury results in serious complications if the diagnosis is delayed. The authors experienced a 63-year-old patient who slipped on the stairs with simple contusion and skin laceration. But, he was finally diagnosed with pseudoaneurysm of tibioperoneal trunk of tibial artery on magnetic resonance imaging and 3-dimensional computed tomography angiogram performed in two weeks due to aggravation of the symptoms. To the best of my knowledge, pseudoaneurysm of tibio-peroneal trunk caused by minor blunt trauma has not been reported till now in Korea. So we report this case with a review of the relevant literature.

• Journal of the Korean Society of Food Culture
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• v.9 no.1
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• pp.53-59
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• 1994

This study was attempted to investigate the effects of preheating treatment and chitosan addition on the textural properties of Korean radish during salting. For this study, we determined the changes in textural properties by compression, puncture, cutting tests respectively and the changes in pectin fractions were also determined. Sensory parameters such as hardness, crispness and toughness were evaluated by sensory analysis and their results were correlated with those by Instron. The results were as follows. The compression force of nonpreheated Korean radish was increased by chitosan addition, whereas that of preheated one was decreased during salting. The puncture force from all the samples of Korean radish decreased, however, chitosan addition showed higher puncture force. The cutting force of nonpreheated Korean radish increased during salting and those from nonpreheated and preheated ones were increased by chitosan addition. During salting hot water soluble pectin(HWSP) of nonpreheated Korean radish increased and 0.4% Na-hexametaphosphate soluble pectin(HXSP) and 0.05 N-HCl soluble pectin(HCISP) decreased respectively. However, HXSP was decreased by preheating treatment. On the contrary, the results were reversed by chitosan addition. Hardness and crispness of nonpreheated Korean radish decreased and toughness increased respectively during salting. However, toughness was decreased by preheating treatment and hardness was increased by chitosan addition. Compression and puncture forces were highly correlated with sensory parameters such as hardness and crispness, whereas cutting force was more correlated with toughness. From these results, it seems that the textural properties were improved by chitosan addition in both nonpreheated and preheated Korean radish. The preheating treatment was effective in the early stage of salting. However, combination of both treatments showed little effect during salting.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.6
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• pp.476-484
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• 2017

The purpose of this paper is to verify the structural integrity of a region with numerous penetration-holes in offshore structures such as semi-submersible rig and FPSO. In order to effectively check the yielding and buckling strength of plate members with penetration-holes, a screening analysis program was developed with the FE analysis tool to generate fine meshed model using the theoretical and analysis methods. When a hole is appeared in the plate structure members, the flow of stress is altered such that concentrations of stress form near the hole. Stress concentrations are of concern during both preliminary and detail design and need to be addressed from the perspectives of strength. To configure the geometrical shape, very fine meshed FE analysis is needed as the most accurate method. However, this method is practically impossible to apply for the strength verifications for all perforated plates. In this paper, screening analysis method was introduced to reduce analysis tasks prior to detailed FE analysis. This method is applied to not only the peak stress calculation combined stress concentration factor with nominal stress but also nominal equivalent stress calculation considering cutout effects. The areas investigated by very fine meshed analysis were to be chosen through screening analysis without any reinforcements for penetration-holes. If screening analysis results did not satisfy the acceptance criteria, direct FE analysis method as the 2nd step approach were applied with one of the coarse meshed model considering hole or with the very fine meshed model considering the hole shape and size. In order to effectively perform the local fine meshed analysis, automatic model generating program was developed based on the MSC/PATRAN which is pre-post FE analysis program. Buckling strength was also evaluated by Common Structure Rule (CSR) adopted by IACS as the stress obtained from very fine meshed FE analysis. Due to development of the screening analysis program and automatic FE modeling program, it was able to reduce the design periods and structural analysis costs.

• Journal of Chest Surgery
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• v.39 no.7 s.264
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• pp.544-548
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• 2006

Background: The purpose of this study is to evaluate the validity of a combined high saphenous vein division and sclerotherapy without sacrificing saphenous vein for varicose vein. Material and Method: Between August 2004 and October 2005, 70 limbs in 50 patients were treated by a combined high saphenous vein division and sclero-therapy. The operative indication is valvular incompetence of femoral-saphenous or popliteal-saphenous junction. Patients received local anesthesia and were treated by a combined high saphenous vein division, ligation of incompetent perforating vein and $1{\sim}3%$ sclerosant. Patients received 1 day hospitalization and applied in com-pression stocking for 6 weeks. Patients followed after 1 week, 1 and 3 months. Result: Mean age of patients was $50{\pm}11$. The female was more common. 8 patients was no symptom, another 42 patients complained of pain, heaviness and fatigue of limbs. The symptoms of varicose vein disappeared 1 month after the procedure in all symptomatic patients. 8 patients needed a adjuvant sclerotherapy for residual varicose vein on 1 week after the procedure. There were only minor complications such as hematoma (1), wound infection (1), thrombophlebitis (20), skin blister (10), hyper-pigmentation (1), and skin ulcer (1). Conclusion: We concluded that a combined high saphenous vein division and sclerotherapy without sacrificing saphenous vein for varicose vein is simple, less invasive, economical, and effective treatment for primary varicose vein, and it has a special advantage that saphenous vein can be used as a bypass conduit later. The method was selective in old aged patients.

• Journal of the Korean Magnetics Society
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• v.12 no.5
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• pp.174-178
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• 2002

Ac magnetic field was changed in the vicinity of a flaw because of the distribution of eddy current within a conductor, when the magnetic field was applied to a conductor having a flaw. The flaw detection was performed by using Co-based amorphous wire sensor head. The wire has almost 0 magneto-striction and high permeability. An comparative uniform magnetic field was applied to a 1㎜ thick copper plate and a 25㎛ thick aluminum sheet conductor using spiral typed coil. The size of the coil has 40㎜$\times$40㎜ outer width and 8㎜$\times$8㎜ inner width. The copper plate and the aluminum sheet has 0.5㎜ and 0.1㎜ wide gap, respectively. The frequency range of applied field was 100㎑∼600㎑. The induced voltage difference of 2.5㎷ was obtained in the maximum voltage and minimum one measured across the gap of the 1mm thick conductor. In the case of aluminum sheet, 0.4㎷ was obtained. From this results, the effectiveness of Co-based amorphous wire was confirmed in the ECT technique.

• Journal of Chest Surgery
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• v.32 no.4
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• pp.394-398
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• 1999

Background: According to the changes in the Environmental factors, traumatic diaphragmic rupture is seen in increasing frequency. Many reports described the early diagnostic methods and treatment modalities. In our institution, a study was retrospectively performed to obtain the early diagnostic and treatment methods of diaphragmic ruptures. Material and Method: From January 1994 to April 1998, 20 patients with traumatic rupture of the diaphragm were treated in our institution and We analyzed the patients in preoperative clinical presentations, diagnostic accuracies, associated injuries and postoperative complications. Result: Socially active male patients were affected most. 75% of patients had blunt trauma and 25% had penetrating injury. There were 16 cases of ruptured right diaphragm, 3 cases of left diaphragm and 1 case on both. Preoperative diagnosis were possible in 10 patients (50%) and 6 patients(30%) were diagnosed intraoperatively, but 4 patients (20%) were diagnosed in the late stages. Most common postoperative complication was wound infection, and two died of associated injuries. Conclusion: We conclude that if there is suspicion of diaphragmic rupture after a trauma, careful study and examination is essential and interdepartmental collaboration is very important.