• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.737-742
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• 2007

The method of the reducing duct noise can be classified by passive and active control techniques. However, passive control has a limited effect of noise reduction at low frequencies (below 500Hz) and is limited by the space. On the other hand, active control can overcome these passive control limitations. The active control technique mostly uses the Least-Mean-Square (LMS) algorithm, because the LMS algorithm can easily obtain the complex transfer function in real-time particularly when the Filtered-X LMS (FXLMS) algorithm is applied to an active noise control (ANC) system. However, the convergence performance of the LMS algorithm decreases slightly so it may delay the convergence time when the FXLMS algorithm is applied to the active control of duct noise. Thus the Co-FXLMS algorithm was developed to improve the control performance in order to solve this problem. The Co-FXLMS algorithm is realized by using an estimate of the cross correlation between the adaptation error and the filtered input signal to control the step size. In this paper, the performance of the Co-FXLMS algorithm is presented in comparison with the FXLMS algorithm. Simulation results show that active noise control using Co-FXLMS is effective in reducing duct noise.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제42권
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• pp.2.1-2.6
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• 2020

Background: Facial palsy treatment comprises static and dynamic techniques. Among dynamic techniques, local temporalis transposition represents a reliable solution to achieve facial reanimation. The present study describes a modification of the temporalis tendon transfer using a cryopreserved fascia allograft. Case presentation: Between March 2015 and September 2018, seven patients with facial palsy underwent facial reanimation with temporalis tendon transfer and fascia lata allograft. Patients with long-term palsy were considered, and both physical and social functions were evaluated. The mean follow-up time was 21.5 months. No immediate complications were observed. Patients reported improvement in facial symmetry both in static and dynamic. Improvement was noticed also in articulation, eating, drinking, and saliva control. The Facial Disability Index revealed an improvement both in physical function subscale and in the social/well-being function subscale. Conclusions: This modified orthodromic technique allows to reduce the operative time and the risk of complications connected to the use of autologous tissues. The use of the cryopreserved fascia allografts from cadaveric donors seems to provide promising and long-standing results in the treatment of facial palsy.

• 대한방사선기술학회지:방사선기술과학
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• 제30권3호
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• pp.251-257
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• 2007

디지털 MTF의 정확도를 결정하는 요소로는 정확한 엣지 각도의 결정, 합성 ESF 또는 합성 LSF을 작성을 위한 재 샘플링, 스무징, 커브핏팅 등을 들 수가 있다. 본 실험에서는 Edge를 이용한 MTF커브 핏팅방법을 구현하였고, 슬릿법에 의한 MTF산출결과와 비교하였다. 실험결과 공간주파수 2.0 LP/mm 근방까지의 저주파수영역에서는 엣지법이 높은 수치를 나타내며 2.0 LP/mm 이상의 주파수 영역에서는 MTF값이 역전이 되어 슬릿법이 더욱 높은 값을 나타내었다. 이는 Cunningham의 보고와 완전히 일치한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1807-1812
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• 2004

Sinusoidal wavy channel is one of the most commonly used devices in the industry for achieving mixing and heat transfer. Here we report on results obtained from the DNS of flow inside the wavy channel performed using the finite volume technique. As a primary stage to obtain the optimal design for heat transfer and mixing, this study observed the basic flow structures in a wavy channel. The mass flow rate is kept constant with friction Reynolds number of $Re_{\tau}$ = 140 . Time- and space-averaged and instantaneous flow fields are illustrated to observe the flow structures. Although the direct comparison of results between turbulent wavy and flat channel is somehow difficult due to the different flow phenomena derived from different configuration, here the mean streamwise velocity and RMS of velocities at same $Re_{\tau}$ of two different channels are compared. The basic difference between wavy and flat channel flow is the existence of small scale wall vortices along the walls in a wavy channel. These vortices make flow more complex, which will accompany the increase of heat transfer, pressure drop and drag.

• 한국임상수의학회지
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• 제19권1호
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• pp.73-79
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• 2002

To investigate the usability of frozen canine embryos for embryo transfer in the dog, 19 donors, 3 recipients, and 6 male dogs were used for the experiment. Natural mating or artificial insemination was performed for breeding the bitches in natural estrus. Vaginal smear test along with progesterone titre test were performed to detect the appropriate mating time and the bitches were bred twice during 3-6days following LH surge. Embryo collection was done on 8, 9-11, 12-13 days after the second mating to collect morula and blastocyst. Embryos were frozen using a programmable freezer and preseued in LNE tank. Embryos were thawed in 37$^{\circ}C$ water for 15 seconds and transferred into each uterine horn within 30 minutes. Embryos were collected from 13 bitches of 19 donors(68.4%) and the collected embryos were from between 9 and 13 days after 2nd mating. Embryos were produced both by natural mating(60.0%, 9115) and AI with frozen semen(100.0%, 4/4). Embryos were collected from the donors weighed between 2.5 and 30 kg and their age was from 1.5 to 3 years. 52 embryos were collected from 13 donors and the mean number of embryos was four. The stage of embryos was from 2-cell to gastrula and morulae were colledted mostly from 10 to 11 days after 2nd mating. Embryos were collected evenly from each uterine horn and the rate of embryo collection for the number of corpus luteum was 83.9%. Embryos were transferred to 3 recipients(morula 8, blastocyst 1, gastrula 8), however, no offspring was produced.

• Journal of Welding and Joining
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• 제8권1호
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• pp.31-42
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• 1990

Arc must be stable during welding first of all other factors for obtaining sound weldment, especially in the automation of welding process. Arc stability is somewhat sophisticated phenomenon which is not clearly defined yet. In consumable electrode welding, the voltage and current variation due to metal transfer enables to assess arc stability. Recently, statistical analyses of the voltage and current waveform factors are performed to assess the degress of arc stability which is assessed and controlled by operator's own experience by now. But, considering the increasing need and the trend of automation of welding process, it is necessary to monitor arc stability in real-time. In this sutdy, the modified stability index composed of two voltage and current wvaeform factors (arc time and short circuit time) reduced from four factors (arc time, short circuit time, average arc current and average short circuit current) in Mita's index by the welding electrical circuit modeling is proposed and verified by experiments to be well estimating arc stability in the static sense. Also, the recursive calculation form estimating present arc stability in the dynamic sense is developed for real-time estimation. The results of applying the recursive index during welding show good estimation of arc stability in real-time. Therefore, the results of this study offers the mean for real-time control arc stability.

• 전기학회논문지P
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• 제64권3호
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• pp.169-174
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• 2015

Noise problem that occurs on the road is raising a lot of problems in the economic, social and environmental aspects. The active noise control (ANC) systems based on the filtered-X least mean square(FxLMS) algorithm have a problem with compensating the acoustic feedback of secondary route. However, newly proposed correlation-LMS(CLMS) and expanded CLMS algorithms have slightly much calculation and are minutely behind performance, these have a advantage not in measuring transfer function onerously so that we can easily adapt these in real time. The CLMS and expanded CLMS algorithm was developed to improve the real-time implementation performance under the variable input noise such as road noise environment. In this paper, we compared and analyzed their performance. From the results of the Matlab simulation for an ANC system, it is shown that expanded CLMS algorithms are more convergence speed and keep the desirable performance even in the input of road noise situation.

• Archives of Reconstructive Microsurgery
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• 제12권2호
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• pp.119-124
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• 2003

Introduction : The purpose is a retrospective evaluation of the clinical results of the radial forearm flap transfer for foot reconstruction. Materials and methods : We evaluated 21 cases with medical records including etiology, wound dimension, presence of infection, associated fracture, ischemic time of free flap, complication of donor and recipient site. The final results were evaluated with our clinical score (walking, shoe-in, cosmetic). Results : Defects were located on the heel (12 cases), dorsum of foot (4 cases) and sole (5 cases). Mean wound dimension was $7.56{\times}6.0cm$, and mean ischemic time of free flap was 94.5minute. There were superficial skin necrosis (1 case), recurrent ulceration (2 cases) in recipient site, and no complication in donor site but complaint about cosmetic problem (3 cases). The clinical score showed excellent in 14 cases, good in 4 cases, fair in 1 case and poor in 2 cases. Conclusion : We consider the radial forearm flap could provid the stable and durable restoration of normal foot contour without debulking in the foot reconstruction and achieved normal ambulation and cosmetic satisfaction.

• 대한산업공학회지
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• 제40권3호
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• pp.283-290
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• 2014

In the flat panel display industry, to meet production target quantities and the deadline of production, the scheduler and dispatching systems are major production management systems which control the order of facility production and the distribution of WIP (Work In Process). Especially the delivery time is a key factor of the dispatching system for the time when a lot can be supplied to the facility. In this paper, we use survival analysis methods to identify main factors of the delivery time and to build the delivery time forecasting model. To select important explanatory variables, the cox proportional hazard model is used to. To make a prediction model, the accelerated failure time (AFT) model was used. Performance comparisons were conducted with two other models, which are the technical statistics model based on transfer history and the linear regression model using same explanatory variables with AFT model. As a result, the mean square error (MSE) criteria, the AFT model decreased by 33.8% compared to the statistics prediction model, decreased by 5.3% compared to the linear regression model. This survival analysis approach is applicable to implementing the delivery time estimator in display manufacturing. And it can contribute to improve the productivity and reliability of production management system.

• 대한족부족관절학회지
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• 제16권4호
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• pp.235-240
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• 2012

Purpose: The aim of this study was to evaluate the radiographic and clinical results of short scarf osteotomy that has minimized longitudinal cut for moderate hallux valgus. Materials and Methods: Total 12 patients (12 feet) were reviewed by medical records and radiographs. All patients were female and the mean age at the time of operation was 41.5 years. The mean followup time was 21.2 months. We modified original scarf osteotomy by shortening the longitudinal cut to 15~20 mm in length. Additionally, Akin osteotomy of the first proximal phalanx was done in 7 feet and Weil osteotomy of the second metatarsal was done in 4 feet. First-second intermetatarsal and hallux valgus angles were analyzed radiographically before and after the operation. And the clinical result was assessed by AOFAS (American Orthopaedic Foot and Ankle Society) hallux score. Results: First-second intermetatarsal and hallux valgus angles were reduced from the mean preoperative values of $14.6^{\circ}$ and $32.8^{\circ}$ to $6.5^{\circ}$ and $11.2^{\circ}$, respectively. The mean AOFAS hallux score was increased from 52.4 points preoperatively to 88.2 points at followup. Three complications were found: metatarsal fracture during the operation, painful scar around second metatarsal head after Weil osteotomy and postoperative neuralgia. There was no transfer metatarsalgia or recurrence of hallux valgus during followup. Conclusion: Short scarf osteotomy would be an effective surgical procedure for moderate hallux valgus with the benefits of minimized soft tissue dissection and stable fixation.