• Journal of the Korean Orthopaedic Association
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• v.54 no.3
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• pp.254-260
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• 2019

Purpose: To evaluate the relationship between the knee function at 1 year postoperation and the gap difference (90° flexion gap-extension gap) in total knee replacement. Materials and Methods: Eighty-two consecutive osteoarthritis knees that underwent primary total knee replacement using navigation from March 2017 June 2017 were evaluated prospectively. The gap was measured using navigation after reducing the patella with towel clips. After checking the average values of the medial and lateral gaps at extension and 90° flexion knee, the gap difference (90° flexion gap-extension gap) was calculated. The knees were divided into three groups according to the gap difference (gap difference<0 mm, 0 mm≤gap difference<2 mm, 2 mm≤gap difference). The Knee Society score (KSS) and maximal knee flexion were compared at 1 year postoperation among three groups. Results: The numbers of knees according to groups were 37, 29, and 16 knees in regular order. The average of the KSS knee, KSS function, and maximal knee flexion at the 1-year follow-up were 81.21±8.31, 71.34±9.84, and 126.48°±7.28°, respectively. No statistically significant difference in KSS was observed among the 3 groups. The third group (2 mm≤gap difference) showed a larger maximal knee flexion than the other groups in the Mann-Whitney test. Conclusion: The group of total knee replacement (2 mm≤90° flexion gap-extension gap) showed larger maximal knee flexion than the other groups at the 1-year follow-up in statistics.

• Journal of the Korean Society of Radiology
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• v.11 no.6
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• pp.467-473
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• 2017

Using Digital Imaging and Communications in Medicine(DICOM) and a 3D medical imaging program, the characteristics of the external auditory canal(EAC) were compared. Using images of the ears of 63 different male and female subjects of varying age, this study measured and compared EAC transverse axis lengths, internal diameter circumferences, and upper and lower curvature angles. The findings of the study indicated differences in EAC shapes according not only to age and sex but also to the left and right of the same subject. A comparison between the sexes of the subjects (35 males and 28 females) indicated that, on average, the length of the EAC was 4.75mm longer in males. Based on the lower curvature angle, the interior side of the diameter circumference of the EAC was found to be reduced on average by 37.2% compared to the exterior side. Although the upper curvature angle was on average $25.7^{\circ}$ larger than the lower curvature angle, 4 subjects showed a larger lower curvature angle and large differences between the upper and lower curvature angles were observed in 8 subjects of the younger age group (4~14 years old). This indicated changes in EAC curvature shapes during growth. This study presents a method to raise safety and precision by comparing direct measurements taken through physical means and indirect measurements acquired from existing ear samples. This was possible due to technological developments in which 3D medical image representation technology creates images close to reality, and, through further development, this method is expected to be used for standardization research of EAC shapes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.7
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• pp.1551-1556
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• 2010

In this paper, we propose a new inspection method that applies fuzzy reasoning method considering the difference of brightness and intensity of illumination by bend together. In the preprocessing phase, we compensate the degree of semiconductor images with bilinear interpolation and moment-rotation. Then we use fuzzy reasoning method with the difference of brightness from error region by pattern matching and the difference of intensity of illumination from bends. Then the result is difuzzified and applied to the final inspection process. In experiment which uses 30 real world semiconductors with strait shots and side shots, the proposed method successfully discard the false positive identified by conventional brightness comparison only method without any loss of misidentification.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.678-679
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• 2022

In this paper, information on ankle instability will be acquired and processed by selecting the area of flexion of the ankle among a diverse range of areas of the Healthcare System. In addition, re-damaging of patient's ankle will be prevented on the basis of such information. Moreover, the system of automatically measuring and managing the angles of dorsiflexion and plantarflexion of the ankle by using video will be presented in this System.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.663-669
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• 2011

This paper examines methods to estimate torque and angle in shoulder flexion from surface electromyography(sEMG) signals for intuitive and delicate control of robotic assistance device. Five muscles on the upper arm, three for shoulder flexion and two for shoulder extension, were used to offer favorable sEMG recording conditions in the estimation. The methods tested were the mean absolute value (MAV) with linear regression and the artificial neural network (ANN) method. An optimal condition was sought by varying combination of muscles used and the parameters in each method. The estimation performance was evaluated using the correlation values and normalized root mean square error values. In addition, we discussed their possible use as an estimation of motion intent of a user or as a command input in a physical human-machine interaction system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2773-2779
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• 2013

The purpose of this study was to evaluate of the usefulness and to develop new auxiliary equipment that can bending angle of the bone of the knee various depending on the thickness of the thigh of the human. The subjects agreed for research purposes and were selected from normal person who do not have past knee-related diseases and grouped thin group A and thick group B for the thigh. We set in order to obtain images in the axial direction of the bones of the knee, $35^{\circ}$ to increase by $5^{\circ}$ angle of knee flexion, $45^{\circ}$, to $55^{\circ}$, and we performed combinations of 9 tests by incident angle X-ray per each angle, $40^{\circ}$, $50^{\circ}$ and $60^{\circ}$. As a result, we have developed an Merchant auxillary equipment of X-ray table integral type in radiographic images which was easy to use and could take images of various integral knee joint angles adjusting different body types. Using the auxiliary equipment, in the case of X-ray incident angle $50^{\circ}$ and $60^{\circ}$ with the knee flexion angle of $40^{\circ}$ in group A, and in group B, Knee flexion angle of $45^{\circ}$ and $35^{\circ}$, the X-ray incident angle at $60^{\circ}$, excellent images were derived. Future, it would be very useful in the examination of patients with a variety of body types.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.3
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• pp.392-398
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• 1986

It is often occurred that exhaust pipe of an internal combustion engine should be bent due to some geometrical constraints. Especially for automobiles most of exhaust pipes of engines have curvature to avoid rear axles. In this paper effects of pipe curvature on the exhaust noise of a diesel engine have been studied experimentally. Experiments were carried out on a 4-cycle, 2164cc diesel engine. Two types of curvature, circular arc and retangle, were tested. Sound pressure level (SPL) and power spectrum of the exhaust noise were measured by inserting bent pipes of different curvature dimensions into the exhaust pipe at various engine operating conditions. The following results were obtained from this study. Among the engine operating conditions the exhaust noise was affected mainly by engine revolution speed. The noise was reduced by the circular arc bent pipe. The effectiveness of an arc bent pipe on the noise reduction was dominated by its arc angle and the maximum noise reduction was obtained by the angle of 180.deg.. But the noise reduction could not be obtained by the rectangular bent pipe, and at high engine speed the noise was rather increased due to turbulence of exhaust gas.

• Journal of the Korean Arthroscopy Society
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• v.9 no.2
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• pp.143-147
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• 2005

Purpose: In case of anterior cruciate ligament (ACL) reconstruction, graft tendon is generally fixed in tibial tunnel with knee extended. When reconstructing ACL using hamstring tendon, the authors aim to find out the effect of knee joint position during graft fixation on postoperative knee joint stability and range of motion. Materials and Methods: Prospective study was done on patients who have undergone ACL reconstruction using hamstring tendon from May 2002 to January 2003 We used Rigifix system (Mitek Product, Johnson and Johnson, USA) and Intrafix system for fixation. Thirty nine patients received ACL reconstruction during this period. Excluding 2 patients lost in the follow-up, 37 patients were analyzed. The mean follow-up period was 14 months $(13{\sim}25months)$. Knee position was decided alternatively without any bias. Clinical evaluation was based on Lachman test, pivot shift test, Lysholm score, IKDC(international knee documentation committee) assessment and side to side KT-1000 maximal manual arthrometer difference. Results: After the last follow-up, average postoperative Lysholm score was 93.1 poins(65-98points). According to IKDC score, 26 cases were normal, 10 cases were nearly normal, 1 case was abnormal and we had no case of severe abnormality. The mean difference from the normal side was 2.5 mm under maximal manual loading KT-1000 arthrometer. According to postoperative Lachman test, 32 cases were normal,2 cases were grade I and 1 case was grade II. There were 34 cases of normal, 2 cases of grade I and 1 case of grade II. When using maximal manual KT-1000 arthrometer side to side difference, the difference from the normal side while fixing the tibia at 20'knee flexion was 2.3 mm and at full extention the difference was 2.7 mm. The range of motion at postoperative 1 year showed 5 degree flexion contracture in 1 case at 20 degrees knee flexion and 10 degrees of flexion limitation was observed in 2 cases at full extension. Conclusion: When ACL reconstruction using autogenous hamstring tendon, anterior laxity showed no difference in its stability between two groups. Tibial side fixation at full extension may be helpful in preventing flexion contracture due to overconstrained graft tendon.

• The korean journal of orthodontics
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• v.32 no.4 s.93
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• pp.275-291
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• 2002

Of various factors indicated for effective use of straight wire appliances, there was a great lack of studies both domestic and international about the curvatures of tooth crowns. This study was performed to investigate the labio/buccal clinical crown curvatures of Korean permanent teeth. For this study, three-dimensional laser scanning was performed on 36 dental casts with normal anatomic structures. Andrews plane and Facial axis of clinical crown (FACC) were designated as horizontal and vertical reference planes respectively. 2 or 3 lines, 1mm apart, were drawn superior, inferior, left and right of these reference planes. A three-dimensional coordinate table was made for points formed by crossing these lines, and averages of each coordinate point on the 36 dental casts were obtained. The curvature equation was made using three-dimensional coordinate points (x,y,z) and by this curvature equation, the curve ratio of each tooth was obtained. Curve ratio changes of each section of teeth were calculated by curve ratios of simplified curves. These two dimensional curves were simplified horizontally and vertically Conclusions for this study are as follows. 1. The basic data of labial and buccal clinical crown curvatures were obtained about Korean permanent teeth. 2. No significant difference was found between male and females. 3. Individual tooth characteristics 1) In maxillary central incisors, the difference in the curve ratio between the gingival and incisal sides was greater than for the other teeth. And the gingival side showed a greater curve ratio. 2) Maxillary canines showed more curvatures in the mesio-occlusal surface than the other surfaces. 3) In maxillary $1^{st}$ premolars, more curvatures were found in mesio-occlusal and disto-gingival surface, thus showing a twisted crown surface, but in maxillary $2^{nd}$ premolars, the crown curvatures of mesial and distal ends became parallel to each other. 4) No significant difference in crown curvatures was found between mandibular central and lateral incisors. 5) Occluso-gingival curvatures of mandibular$2^{nd}$ premolar turned out to be more rounded than mandibular $1^{st}$ premolars or maxillary $2^{nd}$ premolars. From the above conclusions, it can be deduced that the same bracket bases can be used for mandibular central and lateral incisors. But for maxillary $1^{st}\;and\;2^{nd}$ premolars and for mandibular $1^{st}\;and\;2^{nd}$ premolars, because crown curvatures showed significant differences, when making bracket bases there is ample reason to make bracket base curves differently for each type of tooth.

• Restorative Dentistry and Endodontics
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• v.33 no.2
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• pp.83-89
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• 2008

The purpose of this study was to evaluate the effect of the polymerization shrinkage and modulus of elasticity of composites on the cusp deflection of class V restoration in premolars. The sixteen extracted upper premolars were divided into 2 groups with similar size. The amounts of cuspal deflection were measured in Class V cavities restored with a flowable composite (Filtek flow) or a universal hybrid composite (Z-250). The bonded interfaces of the sectioned specimens were observed using a scanning electron microscopy (SEM). The polymerization shrinkage and modulus of elasticity of the composites were measured to find out the effect of physical properties of composite resins on the cuspal deflection. The results were as follows. 1. The amounts of cuspal deflection restored with Filtek flow or Z-250 were $2.18\;{\pm}\;0.92{\mu}m$ and $2.95\;{\pm}\;1.13\;{\mu}m$, respectively. Filtek flow showed less cuspal deflection but there was no statistically significant difference (p > 0.05). 2. The two specimens in each group showed gap at the inner portion of the cavity. 3. The polymerization shrinkages of Filtek flow and Z-250 were 4.41% and 2.23% respectively, and the flexural modulus of elasticity of cured Filtek flow (7.77 GPa) was much lower than that of Z-250 (17.43 GPa). 4. The cuspal deflection depends not only on the polymerization shrinkage but also on the modulus of elasticity of composites.