• Investigative Magnetic Resonance Imaging
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• v.6 no.1
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• pp.55-63
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• 2002

Purpose : We investigated the predictive values of relative CBV measured with perfusion MR imaging, and relative CBF measured with SPECT for tissue outcome in acute ischemic stroke. Material and Methods : Thirteen patients, who had acute unilateral middle cerebral artery occlusion, underwent perfusion MR imaging, and $^{99m}Tc-HMPAO$ SPECT within 6 hours after the onset of symptoms. Lesion-to-contralateral ratios of perfusion parameters were measured, and best cut-off values of both parameter ratios with their accuracy to discriminate between regions with and without evolving infarction were calculated. Results : Mean relative CBV ratios in regions with evolving infarction and without evolving infarction were $0.58{\pm}0.27$ and $0.9{\pm}0.17$ (p < 0.001), and mean relative CBF ratios in those regions were $0.41{\pm}0.22$ and $0.71{\pm}0.14$ (p < 0.001). The best cutoff values to discriminate between regions with and without evolving infarction were estimated to be 0.80 for relative CBV ratio and 0.56 for relative CBF ratio. The sensitivity, specificity and efficiency of each cutoff value were 80.6, 87.5, 82.7% for relative CBV ratio, and 72.2, 75.0, 73.0% for relative CBF ratio (p > 0.05 between two parameters). Conclusion Measurement of relative CBV and relative CBE may be useful in predicting tissue outcome in acute ischemic stroke.

• Journal of Bio-Environment Control
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• v.26 no.3
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• pp.215-220
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• 2017

This study was conducted to improve the insufficiency of fruit vegetable grafting system developed by National Institute of Agricultural Sciences, Rural Development Administration. When the rotary blade cut the stem of scions and rootstocks, the grafting failure at curved cutting surfaces happened. The cutting depth of a tomato seedling by a rotated cutter was calculated 0.11 mm even when the cutting arm length and the maximum stem diameter were 50 mm and 5 mm, respectively. Mathematical analysis and high-speed photography showed that there was no problem by cutting in straight the stem of scions and rootstocks. The compression test of seedling stems to design the optimal shape of gripper showed that stems were not completely restored when they were compressed above 0.8 mm and 0.6 mm in case of rootstocks and scion, respectively. This study found that the bending angle of stem of tomato seedlings at the grafting period was 10 degree on average. The optimal gripper finger was the edge finger type which could be precisely set center point by adjusting the distance between fingers. In addition, it was found that most of seedling could be grasped without damage when the finger-to-finger distances is set to 2.5 mm for scion and 3.0 mm for rootstocks and finger are coated by 1 mm-thick flexible material.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.47-48
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• 2006

본 논문에서는 LabVIEW를 이용한 휴대용 3상 유도전동기 회전자 바 고장 진단 시스템을 개발하였다. LabVIEW는 NI사에서 개발한 그래픽컬 프로그래밍 언어로서 VI(Virtual Instrument)기술을 이용하여 계측, 분석, 표현 프로그램에 최적화된 언어이다. 유도전동기의 입력단에 Current Probe를 연결하여 전류를 측정하였고, NI사의 USB-DAQ보드를 이용하여 데이터를 수집한 후 노트북 컴퓨터에서 실행되는 LabVIEW 프로그램에 의해 고장을 진단할 수 있는 실시간 휴대용 진단 시스템을 개발하였다. 회전자 바에 고장이 일어나면 선 전류의 불균형, 손실 증가, 토크맥동과 평균 토크의 감소를 가져올 수 있다. 고장 진단 방법으로는 회전자 바 고장의 특징 주파수를 찾아 진단하는 방법이 있다. 회전자 바 고장에 대하여 1개와 2개 바를 절단한 회전자를 사용하여 각각 실험하였으며, FFT 분석에 의하여 실시간으로 유도전동기 회전자 바 고장을 진단 할 수 있음을 보였다.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.1
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• pp.26-32
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• 2015

Purpose: The main purpose of this study is to suggest application plan of dipping method by comparing & analysing the difference between addition method and dipping method in the manufacture of metal-ceramic substructure of maxillary central incisor (#1), followed by assessing the work efficiency. Materials and Methods: Master die and hard plaster-copied one were produced and then a total of 20 copies, 10 copies for each through addition method and dipping method, were manufactured and experimented. Copings were fixed on the abutment model and invested in epoxy mounting cup. Samples were cut in labial and lingual direction, using cutter and then rubbed on sandpaper, whose 4 points were measured by using digital microscope. Results: The comparison of mean values by using t-test, parametric statistical method, shows overall significant difference (P < 0.05). Conclusion: The result of this study can be suggested as an application plan, since there is no significant difference between addition method and dipping method in the manufacture of metal-ceramic substructure.

• Physical Therapy Korea
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• v.5 no.4
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• pp.1-8
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• 1998

본 연구의 목적은 장애물 높이에 따른 상지 팔운동 제한이 스텝안정화(stabilization step)에 영향을 주는지 알아보기 위하여 실시하였다. 연구대상자는 대학생 남자 14명, 여자 16명으로 총 30명이였으며, 평균 연령은 21.5세이었다. 스텝 안정화는 FASTEX(functional activity System for testing and exercise, Cybex Division of Lumex, Inc., USA)를 이용하여 측정하였다. 장애물의 조건은 1) 장애물이 없는 조건 2) 15 cm 장애물 3) 25 cm 장애물이었고, 팔 운동의 제한 조건은 1) 팔운동을 제한하지 않은 조건 2) 우세 팔의 운동 제한 3) 양쪽 팔을 모두 제한하는 3개의 조건에서 스텝 안정화 시간을 측정하였다. 장애물 요인과 팔운동 제한 요인간에 안정화 시간(stabilization time)의 차이가 있는지 알아보기 위하여 반복이 있는 2요인 분산분석을 실시하였고, 남녀간에 안정화 시간에 차이가 있는지 알아보기 위하여 t-검정을 실시하였다. 장애물이 없는 조건에서 양팔의 운동을 제한하지 않고 측정한 안정화 시간의 평균은 0.89초이었고, 건측의 상지운동을 제한한 상태에서의 평균은 0.88초이었으며, 양쪽 팔의 운동을 모두 제한했을 때의 평균은 0.84초이었다. 15 cm의 장애물이 있는 조건에서 양팔의 운동을 제한하지 않고 측정한 안정화 시간은 평균 0.98초이었고, 건측의 상지운동을 제한한 상태에서의 펑균은 1.00초이었으며, 양쪽 팔의 운동을 모두 제한했을 때의 평균은 1.14초이었다. 25 cm의 장애물이 있는 조건에서 양팔의 운동을 제한하지 않고 측정한 안정화 시간은 평균 1.09초이었고, 건측의 상지운동을 제한한 상태에서의 평균은 1.28초이었으며, 양쪽 팔의 운동을 모두 제한했을 때의 평균은 1.57초이었다. 남녀간의 스텝 안정화 시간에 차이가 있는지 알아본 결과 각각의 조건에서 통계학적으로 유의한 차이가 없었다. 장애물과 팔운동 제한 조건에 따른 스텝 안정화 시간의 차이가 있는지 알아보기 위하여 반복이 있는 2요인 분산분석을 실시한 결과, 장애물의 높이에 따라 스텝 안정화 시간에는 유의한 차이가 있었고(p<0.05), 15 cm, 25 cm 장애물 조건에서는 팔운동 제한 조건에 따른 스텝 안정화 시간에도 유의한 차이가 있었지만(p<0.05), 장애물이 없는 조건에서는 팔운동 제한에 따른 안정화 시간에는 유의한 차이가 없었다. 이상의 결과는 보행중 장애물을 넘고, 한발로 기립하여 안정성을 유지할 때 팔의 운동이 스텝 안정성에 영향을 미친다는 것을 알았고, 이러한 결과는 한팔 또는 두 팔을 사용할 수 없는 편마비환자나 상지 절단환자의 균형 평가나 치료시 고려되어져야 할 것이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4046-4053
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• 2011

In order to increase the accuracy and efficiency in measuring obesity conducted outside the hospitals, we examined not only the Body Mass Index and cutoff values of waist circumference of 3,281 adults but also considered their gender, age and various body characteristics. This study included 1,505 males (45.9%) and 1,776 females (54.1%) who visited the comprehensive health checkup center. The average body fat content of male participants was 22.2%, and their Body Mass Index was 24.4kg/$m^2$. The average Body Mass Index of female participants was 22.9kg/$m^2$. The average of waist circumference of male subjects was 86.2cm while that of female subjects was 76.9cm. The conventional method to measure obesity using BMI and WC only does not reflect the actual body fat which may change according to one's gender and age. Therefore, for those who visit individual's place to measure obesity outside the hospitals only based on BMI and WC, we need a new standard to measure obesity more accurately.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.80-87
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• 2003

This paper proposes a routing scheme for multi-hop LEO satellite networks with inter-satellite links aiming for reducing the number of link handovers while keeping the efficient use of network resource. The proposed routing scheme controls the link handovers by taking account of the deterministic LEO satellite system dynamics, geographical location of a ground terminal and statistic information of call duration. The performance of the proposed routing scheme has been evaluated and compared with previous routing schemes in terms of average number of link handovers during a call, the call blocking and dropping probability, and the network utilization.

• Journal of Chest Surgery
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• v.40 no.7 s.276
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• pp.480-484
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• 2007

Background: Major vascular injuries can jeopardize a patient's life or imperil limb survival. We performed this study to establish an optimal management plan for vascular injuries. Material and Method: We retrospectively reviewed 26 cases of vascular injury that were treated at Pusan National University Hospital from May, 1999 to September, 2004. The age and sex distribution, the locations and causes of vascular injury, the diagnostic tools, the degree of injuries, clinical manifestations, the treatment modality and complications were reviewed. Result: The mean age was 39.5 years (range: $12{\sim}86$) and the male to female ratio was 22 : 4. The injuries were in 6 descending thoracic aortas, 4 femoral arteries, 4 popliteal veins and so on. The causes of injury were iatrogenic in 8 cases, traffic accident in 7, stab injury in 6 and industrial accident in 5. The most commonly used diagnostic tools were CT and angiography. The degrees of arterial injury were pseudoaneurysm in 10 cases, partial severance in 5, complete severance in 3 and thrombosis in 3. The degrees of venous injury were partial severance in 6 cases, complete severance in 2 and arteriovenous fistula in 2. The clinical manifestations were absence of pulse in 8 cases, coldness in 7, chest pain in 6, swelling in 5, bleeding in 5 and so on. The most frequently used type of revascularization was graft interposition in 11 cases. Two arteriovenous fistulae were repaired by endovascular procedure. There was one case of mortality due to multi-organ failure after hemorrhagic shock, There were three major amputations, and two of them were due to delayed diagnosis and treatment. Conclusion: A system for the early diagnosis and treatment is essential for improving limb salvage and patient mortality. As a consequence of the widespread application of endovascular procedures, the incidence of iatrogenic injuries has recently increased. Educating physicians is important for the prevention of iatrogenic injury. Easy communication and cooperation for earlier involvement of a vascular surgeon is also an important factor.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.94-100
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• 2010

Purpose: The purpose of this study was to compare the fracture strength of the zirconia ceramic crowns according to tooth position. Material and methods: After 10 metal dies were made for each group, the zirconia ceramic crowns were fabricated using CAD/CAM system ($Lava^{TM}$ All-Ceramic System) and each crown was cemented on each metal die with resin cement (Rely $X^{TM}$ Unicem). The cemented zirconia ceramic crowns mounted on the testing jig were inclined with 30 degrees to the long axis of the tooth and the universal testing machine was used to measure the fracture strength. Results: 1. The fracture strength of the zirconia ceramic crown in the lower 1st molar (2963 N) had the highest and that in the lower central incisor (1035 N) had the lowest. 2. The fracture strength of zirconia ceramic crown was higher than that of the IPS Empress crowns in all tooth position. 3. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the long axis of the crowns. 4. There were no significant differences on the fracture strength of the zirconia ceramic crowns according to tooth position except in premolar group. Conclusion: Within the limitations of this study, the results suggested that strength of zirconia ceramic crown is satisfactory for clinical use.

• The Korean Journal of Applied Statistics
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• v.33 no.6
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• pp.777-789
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• 2020

COVID-19 has been rapidly spread world wide since late December 2019. In this paper, our interest is to estimate distribution of incubation time defined as period between infection of virus and the onset. Due to the limit of accessibility and asymptomatic feature of COVID-19 virus, the exact infection and onset time are not always observable. For estimation of incubation time, interval censoring technique is implemented. Furthermore, a competing risk model is applied to estimate the case fatality and cure fraction. Based on the result, the mean incubation time is about 5.4 days and the fatality rate is higher for older and male patient and the cure rate is higher at younger,female and asymptomatic patient.