Nelder-Mead 심플렉스 알고리듬의 수렴에 관한 수치실험

현창헌,이병기 江原大學校 産業技術硏究所 2002 産業技術硏究 Vol.22 No.B

To find the optimal solution as rapidly and exactly as possible with Nelder-Mead simplex algorithm, the present values of the reflection, expansion, contraction and/or shrink parameters of this algorithm are needed to be changed at appropriate time during the search process. The reflection parameter is selected in this study in order to be changed because reflection, expansion and contraction process can be simultaneously effected by only this parameter. Two independent indices for determining whether the present value of the reflection parameter of this algorithm should be changed or not during the search process are suggested in this study. Those indices were made of the equations of Nelder-Mead simplex algorithm's convergence criterion and Dennis-Wood's convergence criterion, repectively. It is appeared that the optimal solution can be find with smaller numbers of objective function evaluation than the original Nelder-Mead's one with fixed parameter when the those indices are used during the search process and the more remarkable reduction effect of the number of an objective function evaluation can be obtained when the latter index is used.

High-Resolution Capacitive Microinclinometer With Oblique Comb Electrodes Using (110) Silicon

Dae-Hun Jeong,Sung-Sik Yun,Byung-Geun Lee,Myung-Lae Lee,Chang-Auk Choi,Jong-Hyun Lee IEEE 2011 Journal of microelectromechanical systems Vol.20 No.6

<P>We propose a new capacitive microinclinometer where oblique comb electrodes and double-folded suspension springs are aligned parallel to the vertical (111) plane of (110) silicon. The oblique comb utilizes both the overlapped area and the gap between movable and stationary electrodes, resulting in a considerable increase in sensitivity (capacitance change/angle). The resolution becomes even higher by taking advantage of the smooth (111) sidewalls of the oblique comb electrodes, which are fabricated using silicon deep reactive ion etching followed by crystalline wet etching. The surface roughness was reduced from 200 (R<SUB>rms</SUB>) to 20 nm (R<SUB>rms</SUB>), and the verticality was improved from 88.7° to 89.7°. The capacitance change of the fabricated inclinometer experimentally ranges from -0.793 to 0.783 pF for the full range of inclination angle (from -90° to 90°). The estimated worst resolution, which is obtainable at an inclination angle of ±85°, was as low as 0.25°.</P>

Usefulness of Skin Explants for Histologic Analysis after Fractional Photothermolysis

( Gyeong Hun Park ),( Sung Eun Chang ),( Seunghyun Bang ),( Kwang Hee Won ),( Chong Hyun Won ),( Mi Woo Lee ),( Jee Ho Choi ),( Kee Chan Moon ) 대한피부과학회 2015 Annals of Dermatology Vol.27 No.3

Background: Fractional laser resurfacing treatment has been extensively investigated and is widely used. However, the mechanism underlying its effects is poorly understood because of the ethical and cosmetic problems of obtaining skin biopsies required to study the changes after laser treatment. Objective: To evaluate the usefulness of human skin explants for the investigation of fractional photothermolysis. Methods: Full-thickness discarded skin was treated in 4 ways: no treatment (control), fractional carbon dioxide laser, fractional Er:YAG laser, and fractional 1,550-nm erbium- doped fiber laser. Both treated and non-treated skin samples were cultured ex vivo at the air-medium interface for 7 days. Frozen tissue was sectioned and stained with hematoxylin & eosin for histologic examination and nitro blue tetrazolium chloride for viability testing. Results: Skin explants cultured for up to 3 days exhibited histologic changes similar to those observed in in vivo studies, including microscopic treatment zones surrounded by a thermal coagulation zone, re-epithelialization, and formation of microscopic epidermal necrotic debris. However, the explant structure lost its original form within 7 days of culture. The viability of skin explants was maintained for 3 days of culture but was also lost within 7 days. Conclusion: The skin explant model may be a useful tool for investigating the immediate or early changes following fractional photothermolysis, but further improvements are required to evaluate the long-term and dermal changes. (Ann Dermatol 27(3) 283∼290, 2015)

Treatment of alopecia areata with tofacitinib

( Ji Su Lee ),( Min-woo Kim ),( Hyun-sun Park ),( Jung Yoon Ohn ),( Hyun-sun Yoon ),( Chang-hun Huh ),( Ohsang Kwon ),( Soyun Cho ) 대한피부과학회 2017 대한피부과학회 학술발표대회집 Vol.69 No.2

Background: Treatment of alopecia areata (AA) is often empiric and not yet satisfactory. Recently, Janus kinase inhibitor showed promising results in Caucasians. Objectives: To investigate efficacy, tolerability, and hair growth trajey of oral tofacitinib monotherapy for Korean AA patients over extended period. Methods: This is a retrospective study of adult AA patients treated with tofacitinib monotherapy for least 4 months. Results: Thirty-six Korean patients with median initial SALT score of 98.9 were included; 91.7% had refractory AA. Twenty-nine (80.6%) patients demonstrated more than 5% SALT change. Twenty patients (55.6%) achieved 50% SALT change at median 7.5 months with 5 mg twice dosage. There were significant differences between SALT 50 achievers and non-achievers: duration of current episode (ρ = 0.009), duration of disease since first onset (ρ = 0.026) and age at onset of first episode (ρ = 0.011). Tofacitinib was well tolerated and there was no any serious adverse effect such as malignancy or tuberculosis reactivation. Conclusion: Oral tofacitinib monotherapy may be effective and tolerable in patients with AA. SALT 50 achievement was associated with followings: duration of current episode, duration of disease since first onset, and age at onset of first episode.

악관절 강직증의 치험례

현영옥,강창희,노양호,천영두,김신헌,이희원 대한악안면성형재건외과학회 2001 Maxillofacial Plastic Reconstructive Surgery Vol.23 No.1

Temporomandibular ankylosis is defined as a situation in which the condyle is fused to the fossa by bone or fibrous tissue. Conditons such as trauma, infection, or systemic disease may predispose to various types of ankylosis, bringing about different levels of limitation in mandibular movement. Most patients with temporomandibular ankylosis are associated with limitation of maximal mouth opening, deviation of the chin toward the affected side, impaired occlusion, chronic pain, compromised oral hygiene, severe facial asymmetry & impeded mandibular molar eruption occurring in childhood. Several techniques to release ankylosis have been described in the literature, showing variable and often unsatisfactory results. The most frequently used operations are gap arthroplasty, interpositional arthroplasty, and exicision and joint reconstruction with autogenous or alloplastic materials. We have managed the two patients of TMJ ankylosis. They had previously TMJ surgery and we treated with gap arthroplasty & active physial therapy. We have obtained favorable results and report these cases with literatures review.

최적화 알고리듬들의 객체지향 C++ 라이브러리의 개발

현창헌,최영일 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.B

There are many optimal design packages, but they are big ones and they have only a few kinds of optimal algorithm coded with Fortran and it is sometimes necessary for user to write down some codes into their packages. So it is hard for user to learn how to use and customize them. More over, there are no commercial home-made software for optimum design. So, in this paper, several famous optimum algorithms are coded and modulized with C^++ which is known as a suitable computer language in order to build up more algorithms into one computer software. All algorithms developed with C++ here were tested for comparison with optimization tool box of MATLAB and are superior to MATLAB.

평면도의 최소 영역 평가에서 유전자 알고리듬과 심플렉스 방법의 비교

현창헌,신상철 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.B

The definition of flatness is given by ISO. ANSI, KS. etc. but those standards don't mention about the specific methods for the flatness. So various solution models that are based on the Minimum Zone Method have been proposed as an optimization problem for the minimax curve fitting. But it has been rare to compare some optimization algorithms to make a guideline for choosing better algorithms in this field. Hence this paper examined and compared Genetic Algorithm and Simplex Method to the evaluation of flatness. As a result. Genetic Algorithm gave the better or equal flatness than Simplx Method but it has the inefficiency caused from the large number of iteration. Therefore, in the future. another researches about alternative algorithms including Hybrid Genetic Algorithm should be achieved to improve the efficiency of Genetic Algorithm for the evaluation of flatness.

텔레스코픽 크라운 임플란트 지지 피개의치와 치아 지지 피개의치의 하악골내 응력분포에 관한 유한요소분석

이창규,백장현,김태훈,김민정,김형섭,권긍록,우이형 대한치과보철학회 2012 대한치과보철학회지 Vol.50 No.1

PURPOSE. The purpose of this study was to investigate the stress distribution in mandibular implant-supported overdentures and tooth-supported overdentures with telescopic crowns. MATERIALS AND METHODS. The assumption of this study was that there were 2, 3, 4 natural teeth and implants which are located in the second premolar and canine regions in various distributed conditions. The mandible, teeth (or implants and abutments), and connectors are modeled, and analyzed with the commercial software, ANSYS Version 10.1. Stress distribution was evaluated under 150 N vertical load bilaterally on 3 experimental conditions - between canine areas, canine and 2nd premolars, 10 mm posterior to 2nd premolars. RESULTS. Overall, the case of the implant group showed more stress than the case of the teeth group in stress distribution to bone. In stress distribution to superstructures of tooth and implants, there was no significant difference between TH group and IM group and the highest stress appeared in TH-IV and IM-IV. The stress caused from bar was much higher than those of implant and tooth. TH group showed less stress than IM group in stress distribution to abutment teeth and implant. CONCLUSION. The results shows that it is crucial to make sure that distance between impact loading point and abutment tooth does not get too far apart, and if it does, it is at best to set abutment tooth on premolar tooth region. It will be necessary to conduct more experiments on effects on implants, natural teeth and bone, in order to apply these results to a clinical treatment. 연구 목적: 이 연구의 목적은 텔레스코픽 크라운 하악 임플란트 지지 피개의치와 치아 지지 피개의치에서 지대치의 수와 위치에 따른 응력 분산을 비교하기 위함이다. 연구 재료 및 방법: 본 연구에서는 임플란트를 4개 식립하고 임플란트 지지 피개의치로 설계하였고, 식립 위치를 견치와 소구치 부위에 위치 별로 3개 또는 2개 존재시를 실험군으로 설정하였다. 자연치아를 갖는 경우도 견치와 제2소구치 4개를 가진 경우를 대조군으로 설정하고 부위별로 3개 또는 2개를 가지는 경우를 실험군으로 설정하였다. ANSYS Version 10.1 (Swanson, Inc., USA)로 분석하였다. 결과: 악골내 응력의 경우, 전반적으로 임플란트(IM)로만 구성된 경우가 치아(TH)로만 구성된 경우에 비해 응력이 크게 발생하였다. 상부구조의 경우, 치아군(TH)과 임플란트군(IM) 사이의 차이는 크게 없었으며 편측 견치와 제2소구치에 지대치 또는 임플란트가 위치하는 경우 가장 큰 응력이 나타났고 바(bar)에서 발생된 응력이 임플란트와 치아에서 발생되는 응력에 비해 상대적으로 훨씬 크게 발생하였다. 지대치와 임플란트의 경우, 치아군(TH)이 임플란트군(IM)보다 응력이 작게 발생하였다. 결론: 본 연구의 결과로부터 지대치(임플란트 또는 치아)를 설정할 때는 하중작용점과 지대치 사이의 거리가 너무 길어지지 않도록 지대치의 수와 위치를 확보해야 하며 소구치 자리에 지대치를 확보하는 것이 유리하다. 앞으로, 실제 임상에 적용하였을 경우, 임플란트 및 자연치아와 악골에 미치는 결과에 대한 연구가 더 필요할 것으로 생각된다.

퍼지 simplex search 알고리듬을 이용한 동력 스크류 효율의 최적설계

현창헌,이병기 江原大學校 産業技術硏究所 2002 産業技術硏究 Vol.22 No.A

The Nelder-Mead simplex algorithm has been one of the most widely used methods for the nonlinear unconstrained optimization, since 1965. Recently, the new algorithm, (so-called the Fuzzy Simplex Algorithm), with fuzzy logic controllers for the expansion, reflection and contraction process of this algorithm has been proposed. In this paper, this new algorithm is developed. And, the formulation for the optimum design of the power screw's efficiency is made. And then, the developed fuzzy simplex algorithm as well as the original one is applied to this optimum design problem. The Fuzzy simplex algorithm results in a faster convergence in this problem, as reported in other study, too.

뇌수막종에 대한 고식적 방사선 치료 : 7예 치험보고 Experience of 7 Cases

이창훈,윤상민,이승훈,김종현 대한신경외과학회 1995 Journal of Korean neurosurgical society Vol.24 No.12

Meningiomas had long been considered radioresistant and therefore the role of radiation therapy in its treatment remains controversial. Lately, however, most of the retrospective analysis of meningiomas indicates that radiation therapy does show some degree of beneficial effects not only for malignant but also for benign meningiomas with the advanced technology and increased amount of radiation therapy, the rate of growth of tumor had been successfully slowed and local recurrence rate is also reduced following subtotal resection. We have performed conventional high dose radiation therapy on 7 cases of meningiomas (four cases of meningotheliomatous meningiomas, and three cases of malignant meningiomas). Of the 7 cases, the residual mass of 6 had decreased in size and neurological improvement was also evident. However, the 7th case resulted in complicated hydrocephalus. These cases are presented and the effect of conventional radiation therapy is discussed together with the review of literatures.