• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.109-119
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• 2017

In the present study, to determine walking imbalance using the walking analysis method, where limitations in the existing walking analysis have been minimized, we propose a new walking analysis method that adopts the following: self-developed equipment to measure the angles of left-right hip joints and knee joints; a determination system using symmetry index (SI); and dynamic time warping (DTW) similarity analysis algorithm to analyze individual walking styles. Normal and imbalanced walking tests were conducted for 12 subjects without walking disorder. From the SI calculation to determine imbalanced walking, both the normal and imbalanced walking styles can be determined using the angle measurements of the left-right hip joints and knee joints. In the analysis of the individual walking styles, the similarities at the center of the lower back, left-right thighs, and dorsum of the feet of the 12 subjects in both normal and imbalanced walking cases were compared. From the similarity analysis of the measured values during the normal and imbalanced walking tests, I determined that the walking pattern does not maintain the same stance when the body parts move during walking.

• Korea journal of population studies
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• v.28 no.2
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• pp.1-32
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• 2005

The optimum population of a society or country can be defined as 'the population growth path that maximizes the welfare level of the society over the whole generations of both the present and the future, under the paths allowed by its endowments of production factors such as technology, capital and labor'. Thus, the optimum size or growth rate of population depends on: (i) the social welfare function, (ii) the production function, and (iii)demographic economic interrelationship which defines how the national income is disposed into consumption(birth and education of children included) and savings on the one hand and how the demographic and economic change induced thereby, in turn, affect production capacities on the other. The optimum population growth path can, then, be derived in the process of dynamic optimization of (i) under the constraints of (ii) and (iii), which will give us the optimum population growth rate defined as a function of parameters thereof. This paper estimates the optimum population growth rate of Korea by: specifying (i), (ii), and (iii) based on the recent development of economic theories, solving the dynamic optimization problem and inserting empirical estimates in Korea as the parametric values. The result shows that the optimum path of population growth in Korea is around TFR=1.81, which is affected most sensitively, in terms of the size of the partial elasticity around the optimum path, by the cost of children, share of capital income, consumption rate, time preference, population elasticity of utility function, etc. According to a survey implemented as a follow up study, there are quite a significant variations in the perceived cost of children, time preference rate, population elasticity of utility across different socio-economic classes in Korea, which implied that, compared to their counterparts, older generation and more highly educated classes prefer higher growth path for the population of Korea.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.4 s.54
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• pp.289-293
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• 2005

Nowadays there are many sun protection cosmetics including organic or inorganic UV filter as an active ingredient. Chemically stable inorganic sunsEreen agents, usually metal oxides, we widely employed in high SPF products. Titanium dioxide is one of the most frequently used inorganic UV filters. It has been used as pigments for a long period of cosmetic history. With the development of micronization techniques, it becomes possible to incorporate titanium dioxide in sunscreen formulations without whitening effect and it becomes an important research topic. However, there are very few works related to quantitations of titanium dioxide in sunscreen products. In this research, we analyzed amounts of titanium dioxide in sunscreen cosmetics by adapting redof titration, reduction of Ti(IV) to Ti(III) and reoxidation to Ti(IV). After calcification of other organic ingredients of cosmetics, titanium dioxide is dissolved by hot sulfuric acid. The dissolved Ti(IV) is reduced to the Ti(III) by adding aluminum metals. The reduced Ti(III) is titrated against a standard oxidizing agent, Fe(III) (ammonium iron(III) sulfate), with potassium thiocyanate as an indicator In order to test accuracy and applicability of the proposed method, we analyzed the amounts of titanium dioxide in four types of sunscreen cosmetics, such as cream, make-up base, foundation and powder, after adding known amounts of titanium dioxide $(1{\sim}25w/w%)$. The percent recoveries of the titanium dioxide in four types of formulations were in the range between 96 and 105%. We also analyzed 7 commercial cosmetic products labeled titanium dioxide as an ingredient and compared the results with those of obtained from ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry), one of the most powerful atomic analysis techniques. The results showed that the titrated amounts were well coincided with the analyzed amounts of titanium dioxide by ICP-AES. Although instrumental analytical methods, ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) and ICP-AES, are the best for the analysis of titanium, it is hard to adopt because of their high prices for small cosmetic companies. It was found that the volumetric method presented here gat e quantitative and reliable results with routine lab-wares and chemicals.

• Journal of the Korean Orthopaedic Association
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• v.54 no.6
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• pp.537-546
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• 2019

Purpose: Anteromedial (AM), posterolateral (PL), anterior, and posterior remnant preserving anterior cruciate ligament (ACL) reconstructions were conducted on patients with partial ACL tears based on the arthroscopic findings. The clinical results of the four groups were compared. Materials and Methods: This study included 98 patients who underwent a remnant preserving ACL reconstruction from January 2013 to June 2016 and could be followed-up for at least two years. The subjects were categorized into four groups according to the selective bundles reconstructed: group A, anteromedial selective bundle reconstruction; group B, posterolateral selective bundle reconstruction; group C, anterior bundle reconstruction; and group D, posterior bundle reconstruction. The preoperative and postoperative anterior translation from the stress X-ray, International Knee Documentation Committee Subjective Knee Form (IKDC SKF) score, Lysholm score, and hospital for special surgery (HSS) score were compared. Results: All four groups showed significant improvement in anterior translation on the stress X-ray conducted with knees at 15° flexion, IKDC SKF score, Lysholm score, and HSS score postoperatively (in all groups, p<0.001). No intergroup differences were observed in terms of the functional outcomes except that preoperative IKDC SKF score was higher in the C group than in the A group (p=0.021), and the preoperative Lysholm score was higher in the B group than in the A group (p=0.03). Conclusion: After the AM, PL, anterior, and posterior remnant preserving ACL reconstructions, all four groups showed satisfactory results in terms of the anteroposterior stability and functional knee scores with no significant intergroup differences.

• Journal of the Korean Arthroscopy Society
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• v.12 no.2
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• pp.107-111
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• 2008

Purpose: To evaluate the clinical and radiographical results of arthroscopic meniscectomy in patients aged over 50 with minimum 3-year follow-up. Materials and Methods: Of the patients who had undergone arthroscopic meniscectomies between Dec. 1997 and Dec. 2003, 36 patients(36 knees) were available for retrospective evaluation. The average age at the time of surgery was 56.4 years and the mean follow-up period was 63 months. According to the Kellgren-Lawrence classification, grade I change were noted in 16 patients, II in 12, III in 6 and IV in 2. According to Outerbridge classification, grade I articular lesions were noted in 16 patients, II in 10, III in 7 and IV in 3. Postoperative Lysholm score, patient s subjective satisfaction and radiographic changes were evaluated retrospectively. Results: Twenty-four patients(66.7%) were good or excellent for the Lysholm score and 26 patients(72.2%) were satisfied at final follow-up. Tibiofemoral angle was changes from mean valgus 3.9 degrees to mean valgus 2.6 degrees and 22 patients(61.1%) showed the progression of osteoarthritic changes. Conclusion: The satisfactory results could be obtained in 72.2% of patients aged over 50 with a minimal follow-up of 3 years after arthroscopic meniscectomy. The results tended to be worse in patients with moderate or severe tibiofemoral osteoarthritic changes or with articular cartilage lesions.

• Journal of the Korean Arthroscopy Society
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• v.10 no.1
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• pp.53-60
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• 2006

Purpose: This study is to analyze the clinical and radiological results after arthroscopic reduction and internal fixation of intra-articular fractures of lateral tibial plateau. Materials and Methods: The subject of the study are the 13 cases of the patients visited orthopedics surgery during March year 2000 to August year 2004 because of intra-articular fractures of lateral tibial plateau and were treated with arthroscopic reduction and internal fixation. X-rays and CT or MRI were both carried out to identify the precise pattern of fracture and the degree of depression which showed out to be all type 2 by Schatzker fracture classification. And in 9 of the cases, autogenous and allogenous bone grafts were given as bone loss were severe. The average age was 48, age group between 31 and 66, and average follow up period of about 38 months ($13{\sim}65months$). Radiological ratings were given by comparing the X-rays of degree of joint congruency before and after the operation, functional ratings by analyzing IKDC score and Lysholm score. Combined injuries observed after arthroscopy were posterior cruciate ligament injury in 1 case, meniscus injury in 4 cases and medial collateral ligament in 2 cases. Results: During follow up, X-rays showed well-maintained reduction of articular surface in all cases and no complications such as joint depression, fracture reduction loss, angular deformity or malunion were found. Average Lysholm score at last follow up was 87 points ranging from 65 to 97, in 8 of the cases excellent, 3 good, 1 fair and 1 poor according to Lynsholm classification. Average IKDC score was 92 (from 82 to 99). Conclusion: Not only does arthroscopic reduction of lateral tibial plateau fracture bring exact reduction of articular surface, but also, is considered to be a good way of operation to diagnose and treat combined injuries of knee joint using arthroscopy.

• Journal of the Korean Arthroscopy Society
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• v.4 no.1
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• pp.1-6
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• 2000

Purpose : The purpose of this study was to compare the results of ACL reconstruction using bone-patellar tendon-bone to hamstring. Materials and Methods : Thirty-two ACL reconstructions with autogenous BPTB and eighteen reconstructions with hamstring were compared in terms of functional outcome, stability and tunnel expansion. Results : The functional score of BPTB group was higher than hamstring group in OAK(Orthopadishe Arbeitsguppe Knie) and IKDC(International Knee Documentation Committee) system. In BPTB group, OAK scores were 71.6$({\pm}10.0)$ preoperatively and 88.5$({\pm}7.9)$ finally. In hamstring group, OAK scores were 73.9$({\pm}11.5)$ and 82.5$({\pm}12.9)$ respectively. There was no difference in stability checked by either $KT-1000^{TM}$ or stress view. Anterior tibial translation measured by $KT-1000^{TM}$ were 2.4$({\pm}1.8)$mm in BPTB and 2.3$({\pm}2.4)$mm in hamstring group. Anterior tibial translation in stress view were 2.8$({\pm}3.4)$mm in BPTB and 2.8$({\pm}2.5)$mm in hamstring group. There was no difference in tibial tunnel expansion but femoral tunnel was more enlarged in hamstring group than BPTB (P=0.03). Conclusion : As there was no difference in stability between two groups, it seems prudent to select either graft defend on such factors as anterior knee pain, skeletal maturity and cosmetic concern. Tunnel expansion seems not to affect stability, but further study is needed to confirm that decrease of which might improve stability.

• KIPS Transactions on Software and Data Engineering
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• v.2 no.10
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• pp.723-730
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• 2013

This paper presents the design of an arm gesture recognition system using Kinect sensor. A variety of methods have been proposed for gesture recognition, ranging from the use of Dynamic Time Warping(DTW) to Hidden Markov Models(HMM). Our system learns a unique HMM corresponding to each arm gesture from a set of sequential skeleton data. Whenever the same gesture is performed, the trajectory of each joint captured by Kinect sensor may much differ from the previous, depending on the length and/or the orientation of the subject's arm. In order to obtain the robust performance independent of these conditions, the proposed system executes the feature transformation, in which the feature vectors of joint positions are transformed into those of angles between joints. To improve the computational efficiency for learning and using HMMs, our system also performs the k-means clustering to get one-dimensional integer sequences as inputs for discrete HMMs from high-dimensional real-number observation vectors. The dimension reduction and discretization can help our system use HMMs efficiently to recognize gestures in real-time environments. Finally, we demonstrate the recognition performance of our system through some experiments using two different datasets.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.351-361
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• 2012

The leading surgical method for correcting the misalignment of the varus and valgus in the knee joint is the high tibial osteotomy (HTO). In the opening wedge HTO (OWHTO), there is no concern about damaging the peroneal nerve on the lateral tibia of the proximal fibula. OWHTO has been the preferred choice, as the opening of the correction angle can be modulated during the operation. The correction of the varus and valgus on the coronal plane are performed adroitly. Nevertheless, there have been numerous reports of unintended changes in the medial tibial plateau and posterior slope angle (PSA). The authors have developed an HTO method using computer-assisted surgery with the aim of addressing the abovementioned problems from an engineer's perspective. CT images of the high tibia were reconstructed three-dimensionally, and a virtual osteotomy was performed on a computer. In addition, this study recommends a surgical method that does not cause changes in the PSA after OWHTO. The results of the study are expected to suggest a clear relationship between the anteromedial cortex oblique angle of each patient and the PSA, and an optimal PSA selection method for individuals.

• Journal of Gastric Cancer
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• v.5 no.4 s.20
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• pp.288-294
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• 2005

Purpose: Superficially spreading (SS) early gastric cancer (EGC) is characterized by wide horizontal extension without deep vertical invasion. It is a relatively rare form of EGC, and it's clinicopathological (C-P) characteristics are not evident. This study aimed to clarify their C-P characteristics. Materials and Methods: We defined SS EGC as invading less than the submucosal layer that measured more than 60 mm in diameter or wider than $5{\times}5cm \;(25cm^2)$ in width. The C-P characteristics and prognosis were compared between 69 patients with SS EGC and 319 patients with the common type EGC (EGC except SS type). Results: For SS EGC lymph node metastases, Lauren's diffuse type, lymphatic invasion were significantly higher than in common type EGC. In patients with SS EGC, all of the metastatic lymph nodes were anatomically distributed within the paragastric region, with fewer along the left gastric artery and common hepatic artery. In 6 cases of SS EGC with resection marqins less than 10 mm, there was no death during the follow-up period (4 to 13 years after operation) if margins were not involved. Age (>58 yrs), tumor site (upper 1/3), lymph node metastasis, submucosal invasion were statistically significant poor prognostic factor in univariate survival analysis. In multivariate survival analysis, age and lymph node metastasis were independent prognostic factors. However, tumor diameter or width was not a significant prognostic factor. Conclusion: Although SS EGC has histologically distinct properties, gastrectomy with free surgical margins and appropriate lymph node dissection $(D1+{\beta})$ could be a suitable treatment.