• 비파괴검사학회지
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• 제25권4호
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• pp.287-293
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• 2005

유도초음파는 박판이나 봉재와 같은 구조를 효율적으로 검사할 수 있는 초음파로 주목받고 있으며, 더불어 시험체를 비접촉으로 검사할 수 있는 기법이 개발되면서 다양한 분야에 응용하기 위해 연구되고 있다. 본 연구에서는 비접촉식 초음파기법과 유도초음파의 장점을 결합하여 기존의 검사기법에 비해 효율적인 검사기법을 제안하고자 하였으며, 실험적인 검증을 위해 알루미늄 박판에 모의 부식결함을 가공하여 두께감육을 검출하고 평가하였다. 제안된 비접촉식 초음파기법으로는 EMAT을 이용하여 유도초음파를 발생 및 수신하였다. 선택된 유도초음파 모드의 분산거동특성에서 모드 컷-오프는 두께 감육을 검출할 수 있는 정성적인 파라미터이며, 군속도 변화는 두께 감육의 깊이를 정량적으로 평가할 수 있는 파라미터로 나타났다.

• Journal of Korean Neurosurgical Society
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• 제37권3호
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• pp.217-222
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• 2005

Objective: To achieve optimal fit of implant, it is necessary to bend the implant during spine surgery. Bending procedure may decrease stiffness of plate especially made of titanium and stainless steel. Typically titanium suffers adverse effects including early crack propagation when it is bent. We investigate whether 6 degree bending of titanium plates would decrease the stiffness after full cyclic loading by comparing with non-bending titanium plates group. Methods: Authors experimented 40 titanium alloy plates of 57mm in length, manufactured by 5 different companies. Total 40 plates were divided into two groups (20 bent plates for experimental group and 20 non-bent plates for control group). Twenty plates of experimental group were bent to 6 degree with 3-point bending technique and verified with image analyzer. Using the electron microscope, we sought for a initial crack before and after 3-point bending. Mechanical testing by means of 6000 cyclic axial-compression loading of 35N in compression with moment arm of 35mm-1.1 Nm was conducted on each plate and followed by the electron microscopic examination to detect crack or fissure on plates. Results: The stiffness was decreased after 6000 cyclic loading, but there was no statistically significant difference in stiffness between experimental and control group. There was no evidence of change in grain structure on the electron microscopic magnification. Conclusion: The titanium cervical plates can be bent to 6 degree without any crack or weakness of plate. We also assume that minimal bending may increase the resistance to fatigue fracture in cervical flexion-extension movement.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.93-99
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• 2016

Background: Industrial X-ray CT system is normally applied to non-destructive testing (NDT) for industrial product made from metal. Furthermore there are some special CT systems, which have an ability to inspect nuclear fuel assemblies or rocket motors, using high power and high energy (more than 6 MeV) pulsed X-ray source. In these case, pulsed X-ray are produced by the electron linear accelerator, and a huge number of photons with a wide energy spectrum are produced within a very short period. Consequently, it is difficult to measure the X-ray energy spectrum for such accelerator-based X-ray sources using simple spectrometry. Due to this difficulty, unexpected images and artifacts which lead to incorrect density information and dimensions of specimens cannot be avoided in CT images. For getting highly precise CT images, it is important to know the precise energy spectrum of emitted X-rays. Materials and Methods: In order to realize it we investigated a new approach utilizing the Bayesian estimation method combined with an attenuation curve measurement using step shaped attenuation material. This method was validated by precise measurement of energy spectrum from a 1 MeV electron accelerator. In this study, to extend the applicable X-ray energy range we tried to measure energy spectra of X-ray sources from 6 and 9 MeV linear accelerators by using the recently developed method. Results and Discussion: In this study, an attenuation curves are measured by using a step-shaped attenuation materials of aluminum and steel individually, and the each X-ray spectrum is reconstructed from the measured attenuation curve by the spectrum type Bayesian estimation method. Conclusion: The obtained result shows good agreement with simulated spectra, and the presently developed technique is adaptable for high energy X-ray source more than 6 MeV.

• 비파괴검사학회지
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• 제36권6호
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• pp.466-473
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• 2016

선박 건조과정에서 이면부의 도장손상은 용접과정에서 과도한 입열량(heat input)에 따른 전도의 영향으로 손상 방지를 위해서는 용접온도 계측에 의한 적절한 입열량 제어가 필요하다. 온도 계측에는 접촉식, 비접촉식 방법이 있으며 열화상 시스템은 대표적인 비접촉식 방법이다. 하지만 일반적인 열화상 시스템의 탐지센서(detector)는 고온물체에서 방출되는 복사량(radiant quantity)이 과도하면 백화현상(saturation)으로 인해 온도계측이 불가능해진다. 따라서 본 논문에서는 열화상 시스템에 집속되는 과도한 복사량을 차단하기 위해 중성밀도필터(neutral density filter)를 결합하여 고온 물체의 온도를 $3000^{\circ}C$까지 정량적으로 계측하기 위한 복사 에너지 필터링을 연구하였다.

• 대한정형도수물리치료학회지
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• 제16권1호
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• pp.26-36
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• 2010

Purpose: The study compared the muscle activity and ratio of upper trapezius (UT) to lower trapezius (LT) activity between acute and chronic whiplash-associated disorder (WAD) patients. Methods: Twelve healthy (male: 7), 14 acute WAD (male: 7), and 11 chronic WAD (male: 3) volunteers participated in this study. Electromyography using a surface EMG recorded the activity of the upper trapezius and lower trapezius of both shoulders (dominant and non-dominant) during $120^{\circ}$ elevation when standing and shoulder depression when sitting. The testing order was selected randomly. Subjects were asked to maintain each experimental position for 5 seconds at end range. EMG activity was normalized using the maximal voluntary isometric contraction (MVIC) elicited using a manual muscle-testing technique. One-way repeated measures analysis of variance (ANOVA) was used to compare the average root mean square (RMS) value of EMG activity for each condition. Results: The EMG activity of the dominant UT for chronic WAD subjects was significantly higher than for acute WAD subjects during $120^{\circ}$ elevation (p<.05). The EMG activity of the dominant LT for acute WAD subjects was significantly lower than for the control group (p<.05) during $120^{\circ}$ elevation. The EMG activity of the dominant LT for WAD patients was significantly lower than for the control group during shoulder depression (p<.05), and the chronic WAD patients scored significantly the lowest (p<.01). The dominant UT/LT for chronic WAD patients was significantly higher than the ratio for acute WAD subjects during shoulder depression (p<.05); this result was higher than for the control group (p<.01). The non-dominant UT/LT (ratio) for chronic WAD patients was significantly higher than the ratio for acute WAD subjects during shoulder depression (p<.05). Conclusion: The UT for chronic WAD subjects was hyperactive when compared to the acute WAD subjects, and the was hypoactive for both acute and chronic patients, therefore intra-trapezius imbalance was more prevalent during shoulder depression.

• 패션비즈니스
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• 제24권3호
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• pp.30-39
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• 2020

This study was conducted to identify problems in domestic flame-retardant performance specifications. Currently, the domestic wallcovering anti-inflammatory regulations are not prepared for damage caused by smoke, with the carbonized area as the main function. In particular, given that smoke is the main cause of human casualties and injuries in a fire, it is reasonable that the flame density and toxicity of the wallcovering should also be the main performance indicators. The scope and method of research in this study were as follows. First, a prior study related to fire on various wallcoverings was considered. Second, it raised questions about the effects of smoke in the event of a fire and domestic anti-inflammatory performance tests. Third, textile wallcovering samples were manufactured with viscose rayon for experimental verification of the problems and tested by Korean and EU standards without flame retardant processing to analyze the differences between each regulation. Fourth, the performance of flame retardant wallcovering according to Korean standards was evaluated using smoke density and harmful gas testing methods. The results of each test were as follows. Non-fire retardant wallcovering was rejected by Korea standards. However, B-s1.d0 in Europe. Smoke density testing and harmful gas by domestic combustion processing on the same sample showed that the smoke density increased about 4.3 times more than before, and the harmful gas test showed that the suspension of the post-processing sample slowed earlier than the non-processed sample.

• 대한약침학회지
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• 제15권1호
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• pp.23-28
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• 2012

Objective: This experimental study was designed to investigate the safety and the effectiveness of Samjeong pharmacopuncture solution (SPS) manufactured by using a the lowtemperature extract on process. Methods: To identify the safety and the effectiveness of using SPS as eye drops, we performed applied eye irritation tests on rabbits and antibacterial tests for Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Aspergillus niger, Fusarium oxysporum, and Candida albicans. The eye irritation test was performed according to the toxicity testing regulation of the Korea Food & Drug Administration (2009. 8. 24, KFDA 2009-116). After SPS had been applied on the left eye of the rabbits, eye irritation in the cornea, iris and conjunctiva was observed on the 1st, 2nd, 3rd, 4th & 7th day. After SPS had been dropped on bacterial species that cause keratitis, the minimum inhibition concentration and the size of the inhibition zone were measured. The anti-bacterial potency was also measured by taking the size of inhibition zone. Results: After SPS had been administered on the left eye of the rabbits, none of nine rabbits were found to show abnormal signs or weight changes. After SPS had been administered on the left eye of the rabbits, no eye irritation in the cornea, iris and conjunctiva was observed on the 1st, 2nd, 3rd, 4th & 7th day. No specific response was detected in MIC for bacterial species Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Aspergillus niger, Fusarium oxysporum, and Candida albicans after SPS had been applied. Conclusions: This study suggests that SPS is a non-toxic and non-irritant medicine that does not cause any of eye irritation in rabbits, but it has no antibacterial effects on bacterial species that are well known to cause keratitis. These results suggest that more research is required on extracts from herbal medicines for treating keratitis.

• 비파괴검사학회지
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• 제30권2호
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• pp.121-125
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• 2010

회전기기의 결함진단에 있어서 기존의 방법과 달리 적외선열화상기술은 회전기기의 결함진단에 대해 비접촉, 비파괴 및 상태감시 모니터링을 할 수 있다. 본 논문에서는 적외선열화상 상태진단을 기반으로 하는 회전기기의 결함진단에 대한 새로운 접근법을 제안한다. 따라서 회전기에서 가장 많이 사용되어지는 볼베어링을 이용하여 실험을 수행하였고, 진동 스펙트럼 분석과 적외선열화상을 이용하여 실시간 모니터링을 수행하였다. 적외선열화상기법을 이용하여 볼베어링의 윤활 불균형에 따른 온도 특성을 확인할 수 있었다. 이러한 실험을 통한 결과를 분석 검토하여 향후 산업전반의 회전기기의 상태감시연구에 있어서 다양한 분야에 사용되어 질 것으로 예상된다.

• Restorative Dentistry and Endodontics
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• 제48권2호
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• pp.21.1-21.15
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• 2023

Objectives: This study evaluated the effects of Biodentine (BD), Bio-C Repair (BCR), and mineral trioxide aggregate (MTA) plug on the fracture resistance of simulated immature teeth with replacement root resorption (RRR) and in vitro-induced osteoclastogenesis. Materials and Methods: Sixty bovine incisors simulating immature teeth and RRR were divided into 5 groups: BD and BCR groups, with samples completely filled with the respective materials; MTA group, which utilized a 3-mm apical MTA plug; RRR group, which received no root canal filling; and normal periodontal ligament (PL) group, which had no RRR and no root canal filling. All the teeth underwent cycling loading, and compression strength testing was performed using a universal testing machine. RAW 264.7 macrophages were treated with 1:16 extracts of BD, BCR, and MTA containing receptor activator of nuclear factor-kappa B ligand (RANKL) for 5 days. RANKL-induced osteoclast differentiation was assessed by staining with tartrate-resistant acid phosphatase. The fracture load and osteoclast number were analyzed using 1-way ANOVA and Tukey's test (α = 0.05). Results: No significant difference in fracture resistance was observed among the groups (p > 0.05). All materials similarly inhibited osteoclastogenesis (p > 0.05), except for BCR, which led to a lower percentage of osteoclasts than did MTA (p < 0.0001). Conclusions: The treatment options for non-vital immature teeth with RRR did not strengthen the teeth and promoted a similar resistance to fractures in all cases. BD, MTA, and BCR showed inhibitory effects on osteoclast differentiation, with BCR yielding improved results compared to the other materials.

• 한국구조물진단유지관리공학회 논문집
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• 제19권4호
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• pp.18-24
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• 2015

콘크리트구조물의 진단에 사용되는 비파괴실험법들은 구조물에 손상을 입히지 않고 구조물의 결함이나 강도를 추정할 수 있다는 장점이 있지만 추정값에 대한 신뢰성이 떨어진다는 문제점이 있다. 본 연구에서는 이러한 문제점을 해결하기 위해 2가지 배합으로 총 180개의 공시체를 제작하였고, P파와 S파에 의한 초음파속도 측정, 종진동과 변형진동에 의한 충격공진법 총 4가지의 비파괴실험을 실시하였다. 그리고 실제압축강도 측정을 통해 비파괴실험 결과값의 신뢰성을 비교 분석하였다. 각 비파괴실험법의 결과값에 대한 통계적 분석결과 변동계수값이 가장 낮은 실험법은 S파에 의한 초음파속도법으로 가장 안정적인 관측이 가능한 것으로 나타났다. 한편, 실제압축강도와의 관계를 통해 압축강도 4개의 압축강도 추정식을 제안하였으며 S파에 의한 초음파속도법의 결정계수값이 가장 높은 것으로 나타났다. 향후 다양한 배합조건에 따른 비파괴실험 신뢰성에 대한 보완 연구가 필요할 것으로 판단된다.