• The Journal of Korean Academy of Prosthodontics
• /
• v.31 no.2
• /
• pp.249-270
• /
• 1993

For understanding of anatomy, physiology, and diseases of human TMJ, it is required to evaluate quantitatively the movement of the disc and condyle head of mandible. The histologic section of cadaver TMJ were examined, and the magnification of the MR image and its details of anatomy were evaluated. And then a quantitative analytic method, by comparing the Sectograph and the MR image of vital human TMJ, was proposed. For this study, 15 subjects(Male, 24~35years) were selected from a prosthodontic examination randomly, and each subject’s five interocclusal rubber registration records were made on the ICP, and 5, 10, 15, and 20mmjaw opening positions. All subjects were radiographed with a Denar Quint Sectograph Image System(Denar Corp., USA), and imaged with a MRP-20EX MR Image System(0.2T, Permanent Magnet Type, Hitachi Medical Corp., Japan) using an 100mm diameter bilateral type surface coil. These images were traced on the acetate tracing paper, and analyzed In this study, the findings led to the following conclusions. 1. In comparison of the histologic section of autopsy specimen with the MR image at the same section, the size(dimension) of MR image was 70% of the real one. It was possible to recognize the shape of articular disc, anterior and posterior attachments, and adjacent soft tissues, because of the excellent reproducibility of anatomical structure. 2. When we compared the amount of joint space on MR image with that of joint space on sectograph, the amount of joint space on sectograph was significantly greater than that of joint space on MR image, except at the top of condylar head. 3. The position of minimum joint space on sectograph at intercuspal position didn't coincide with the middle position of articular disc on MR image, and was approximately in the anterior third of posterior band of articular disc. 4. The amount of condylar movement on MR image at opening movement was greater than that of articular disc movement. From Intercuspal position to 5mm jaw-opening movement, the condylar movement showed hinge one, and over the range 5mm jaw-opening it suggested hinge & translatory one. 5. In terms of area variation of articular disc measured on MR image in sagittal plane, the area of posterior band increased with increasing the amount of Jaw opening, but the area of anterior band decreased conversely.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.8
• /
• pp.783-789
• /
• 2012

In this study, turbulent flow and heat transfer characteristics in a helically coiled tube have been numerically investigated. Helically coiled tubes are commonly used in heat exchange systems to enhance the heat transfer rate. Accordingly, they have been widely studied experimentally; however, most studies have focused on the pressure drop and heat transfer correlations. The centrifugal force caused by a helical tube increases the wall shear stress and heat transfer rate on the outer side of the helical tube while decreasing those on the inner side of the tube. Therefore, this study quantitatively shows the variation of the local Nusselt number and friction factor along the circumference at the wall of a helical tube by varying the coil diameter and Reynolds number. It is seen that the local heat transfer rate and wall shear stress greatly decrease near the inner side of the tube, which can affect the safety of the tube materials. Moreover, this study verifies the previous experimental correlations for the friction factor and Nusselt number, and it shows that the correlation between the two in a straight tube can be applied to a helical tube. It is expected that the results of this study can be used as important data for the safety evaluation of heat exchangers and steam generators.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.12
• /
• pp.1301-1307
• /
• 2011

Electrosurgical knee wand (EKW) is a high-frequency thermocautery instrument and is often used for coagulation, ablation, excision, and extirpation of knee ligaments and tissues. In order to maximize the success rate, ease, and safety of knee surgery using EKW and radiofrequency ablation, it is necessary to ensure that the EKW selectively approaches the lesion with utmost accuracy and safety. The key feature of this instrument is its excellent maneuverability. Hence, the authors constructed a tensile spring model based on a shape memory alloy (SMA), which exhibits the shape memory effect. This model can be used in knee surgery as it is considered the most biocompatible femorotibial surgical actuator. The changes in external temperature with current and the thermoelectric characteristics of the SMA were investigated. The relationship between the restoring force and the typical stroke (TS) in response to the conditions in the SMA tensile spring design were evaluated. In conclusion, as the diameter of the SMA tensile spring decreased, the maximum temperature increased. The strain in the actuator caused a stable and proportional increase in the force and induced current for up to 15s, but this increase became very unstable after 30s. Moreover, the relationship between the current and the TS was more stable than that between the current and the restoring force.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.22 no.2
• /
• pp.70-78
• /
• 1989

This experiment was carried out to develop the preparation method of chitosan which has strong antimicrobial activity, and also tried to investigate as a natural food preservative with this chitosan. The antimicrobial activity of chitosan was the strongest when deacetylation of chitin was conducted at $146^{\circ}C$ for 8 hours with $50\%$ sodium hydroxide. The growth of Escherichia coil was completely inhibited by adding this low molecular weight chitosan (M. W, 35,000) at the level of concentration of 75ppm to the medium. The antimicrobial activity was strong enough against such Gram positive bacteria as Staphylococcus sp. and Bacillus sp.. The growth of these strains was inhibited by the concentration of 50ppm but it was varied in its kinds against Gram negative bacteria. The concentration of chitosan re-quired for growth inhibition of microorganisms was 100ppm against Pseudomonas sp. and Vibrio sp., 2,000ppm against Salmonella sp.. The growth of Saccharomyces sp. was inhibited by the concentration of 100ppm, but Hansenula sp., Aspergillus sp., Penicillium sp. and Mu-cor sp. did not inhibited by even more than the concentration of 5,000ppm. The shelf life of Mulkimchi (pickle type Kimchi), containing $0.2\%$ chitosan was 10 days longer than control stored at $5^{\circ}C$.

• Journal of Energy Engineering
• /
• v.25 no.3
• /
• pp.18-26
• /
• 2016

Mineral oil is the most widely used for electrical transformer, though some factors should be considered such as their environmentally harmfulness when it spill and low flash point. To cover these disadvantages, vegetable oil has developed because of its high biodegradability and thermal stability. However, it is necessary that many studies should conduct to reveal the detailed impacts of long-term operation as transformer oil. In this paper, we applied the accelerated aging test which simulate the real transformer circumstances using insulation paper, coil, steel at $150^{\circ}C$, which is higher than normal operation, for 2 weeks. To figure out the oxidation characteristics between mineral oil and vegetable oil test major properties and components such as total acid number, dielectric breakdown and dissolved gas components during that period. As a result of these tests, we found that vegetable oil has higher electric insulation ability than mineral oil though poor total acid number by hydrophile property. Vegetable oil also kept its thermal stability under the given circumstances.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.23 no.3
• /
• pp.645-661
• /
• 2009

The water extract of Dohongsamul-Tang(DHSMT) has been traditionally used to stroke and brain injuries in Oriental Medicine. The present study was designed to investigate the effects of DHSMT on the gene expression profile of cerebral infarction by cDNA microarray in photothrombotic ischemia mouse model. Photothrombotic ischemia was induced in stereotactically held male BALB/c mice using rose bengal and cold light. MRI was performed 24 hours after inducing photothrombosis using 1.5 T MRI and 47 mm surface coil to obtain T2-weighted, and contrast-enhanced images. After MRI test, animal was sacrificed and the brain sections were stained for hematoxylin and eosin and immunohistochemistry. MRI and histological analysis revealed that lesion of thrombotic ischemia was well induced in the cortex with the evidence of biological courses of infarction. The target area of thrombotic infarction was 1 mm anterior to bregma and 3 mm lateral to midline with 2 mm in diameter, which were decreased by administration of DHSMT. To assess gene expression pattern of cerebral infarction, mRNA was isolated and reacted with microarray chip(Agilant's DNA Microarray 44K). Scatter and MA plot analysis were performed to clustering of each functional genes. M value [M=log2(R/G), A={log2(R ${\times}$ G)}/2] was between -0.5 and +0.5 with 40% difference. After pretreatment with DHSMT, the expression levels of mRNA of many genes involved in various signaling pathway such as apoptosis, cell cycle, cell proliferation, response to oxidative stress, immune response, angiogenesis, and inflammatory cytokine were markedly inhibited in photothrombotic ischemia lesion compared to the control group. These results suggest that DHSMT prevent ischemic death of brain on photothrombotic ischemia model of mice through modulation of gene expression at the transcriptional level.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.26 no.2
• /
• pp.90-98
• /
• 2006

Signals captured from a Combo calibration standard tube paly a crucial role in the evaluation of motorized rotating pancake coil (MRPC) probe signals from steam generator (SG) tubes in nuclear power plants (NPPs). Therefore, the Combo tube signals should be consistent and accurate. However, MRPC probe signals are very easily affected by various factors around the tubes so that they can be distorted in their amplitudes and phase angles which are the values specifically used in the evaluation. To overcome this problem, in this study, we explored possibility of simulation to be used as a practical calibration tool far the evaluation of real field signals. For this purpose, we investigated the characteristics of a MRPC probe and a Combo tube. And then using commercial software (VIC-3D) we simulated a set of calibration signals and compared to the experimental signals. From this comparison, we verified the accuracy of the simulated signals. Finally, we evaluated two defects using the simulated Combo tube signals, and the results were compared with those obtained using the actual field calibration signals.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2009.06a
• /
• pp.63-64
• /
• 2009

변환시설의 해체 시 발생한 해체폐기물은 2009년 현재까지 약 354톤이며, 이들 중 탱크, 배관, 반응기, 펌프류 동의 해체금속폐기물이 약 191톤으로 54% 를 차지하고 있다. 이들 해체금속폐기물은 제염 처리공정을 통하여 전량 자체처분폐기물로 전환시키는 것을 목표로 두고 있다. 이는 오염된 금속류를 효과적으로 제염한 다음 자체처분시킴으로서 방사성폐기물에 대한 처분비용을 저감할 수 있기 때문이다. 해체금속폐기물 중 스테인레스강 해체폐기물은 질산 용액을 사용한 초음파화학제염공정으로 제염한 후 자체처분폐기물로 53톤을 전환하였다. 탄소강 해체물의 경우 스팀제염공정으로 제염한 결과 제영 효율은 좋았으나 변환시설 가동 중 유지 보수를 위하여 페인팅을 하였던 해체물의 경우 페인트를 제거하지 않을 경우 스팀제염장치로는 제염이 안 되었다. 탄소강 해체금속폐기물은 약 117톤 발생하였으며, 이들 중 모터, 펌프 등을 제외한 제염 대상 폐기물은 약 80톤이며, 이들을 용융 제염 및 감용을 위하여 기초 연구를 수행한 결과를 바탕으로 약 180kg/batch 용량의 금속용융제염 설비를 제작 설치하여 탄소강 해체금속폐기물 용융제염 처리를 수행 중에 있다. 금속용융은 장치가 간단하고 폐기물 처리량이 비교적 적고 단속적인 운전에 매우 효과적인 고주파 유도로를 사용하였다. 용융장치는 고주파 발진장지와 용해로체로 구성된 고주파 유도설비와 냉각계통으로 구성된다. 고주파발진장치는 철제 200kg을 용해할 수 있는 용량을 갖추었으며, 실험 및 실제 처리 등 용해로체의 크기 변경이 필요할 경우에는 고주파발진기의 출력 주파수를 변경할 수 있게 하였다. 용융 장치의 발진기 부분의 입력전원은 3상, 440V, 60Hz 이며, 출력전원은 200kW, 출력주파수는 lkHz, 3kHz, 5kHz로 구성되어 있으며, 회당 180kg 의 폐기물을 용융할 시에는 3kHz로 고정하여 사용하였다. 용해로체 부분 중 고주파유도가열부는 heating coil 및 절연부로 구성되어 있고, 그 외 support frame과 lever로 구성되어 있다. 용해로체와 고주파 발진장치의 냉각을 위한 냉각설비는 냉각기와 냉매의 저장을 위한 저장조로 구성되어 있으며, 냉각기의 용량은 20RT 이다. 용융로체의 직경은 약 28cm로 크기가 큰 해체물의 장입이 어려워 작은 크기로 세절을 해야만 하며，용융로의 용량을 증가시킬 경우 해체물을 작은 크기로 세절하는 비용을 절감할 수 있을 것이다. 용융 중 시료 채취는 매 배치마다 수행하였으며, 그림3과 같은 시료 채취용 주형 틀에 국자모양의 채취기로 채취하였다. 해체물의 용융시 ingot를 생성하기 위해서 주형틀에 용융물을 장입하기 전 시료를 채취하였다 그림4는 생성된 ingot이며, 이들의 방사능 농도는 배치마다 차이는 있지만 최대 0.05 Bq/g 이하로 나타나 자체처분 폐기물로 전량 전환 가능하였다 그림5 는 해체물에 함유된 우라늄과 불순물을 제거한 슬래그로 방사능농도는 약 12Bq/g 으로 나타났으며, 이들의 발생량은 약 3wt% 정도로 폐기물 발생량이 작았다. 따라서 금속폐기물의 경우 용융제염으로 처리할 경우 폐기물 발생량을 최대로 줄일 수 있어 처리 효율이 기타 처리 공정보다 효율적인 것으로 판단된다.

• Journal of the Korean Society of Radiology
• /
• v.8 no.5
• /
• pp.255-260
• /
• 2014

The acute lumbar pain patients who were unavoidable to take MRI examination were made to take altered lateral recumbent position. they were also not able to control their painfulness and to be in supine position. In this study, it is supposed to increase success rate of the MRI examination through taking the altered lateral recumbent position in using spine and body matrix coil. This altered position made relaxing lumber pain and fatigue for the patients who suffered from sever lumber pain. In these reasons, it decreases the motion artifacts through correcting uncomfortable posture. As a result, qualitative analysis for the image quality was estimated to have average points of supine position A group(lateral recumbent position) of normal candidates and B group(lateral recumbent position) of the abnormal candidates who have sever pain at 4.64, 3.44, and 3.40, respectively. In conclusion, while qualitative analysis in the examination with supine position of the normal patients had significantly high points, the qualitative analysis in the examination with lateral recumbent position of the normal patients and abnormal patients who had sever lumbar pain was almost same. In addition, it was judged that radiologists' imagery interpretation had no other problems in the image evaluation of B group who had acute lumbar pain of abnormal patients. Hereupon, if this technique becomes generalized for the patients who suffer from supine position in the examination, it is supposed to be useful in medical field.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.25 no.1
• /
• pp.15-19
• /
• 2005

Conventional eddy current testing has been used for the detection of the defect-like fatigue crack in the conductive materials, such as aluminum, which uses a sinusoidal signal with very narrow frequency bandwidth, Whereas, the pulsed eddy current method uses a pulse signal with a broad bandwidth. This can allow multi-frequency eddy current testing, and the penetration depth is greater than that of the conventional eddy current testing. In this work, a pulsed eddy current instrument was developed for evaluating the metal loss. The developed instrument was composed of the pulse generator generating the maximum square pulse voltage of 40V, an amplifier controlled up to 52dB, an A/D converter of 16 bit and the sampling frequency of 20 MHz, and an industrial personal computer operated by the Windows program. A pulsed eddy current probe was designed as a pancake type in which the sensing roil was located inside the driving roil. The output signals of the sensing roil increased rapidly wich the step pulse driving voltage かn off, and the latter part of the sensing coil output voltage decreased exponentially with time. The decrement value of the output signals increased as the thickness of the aluminum test piece increased.