녹내장 환자에서 유리체강 내 베바시주맙 주사가 망막신경섬유층에 미치는 영향

박창현,이기일,박혜영,이진해,김인태,박찬기,Chang Hyun Park,Kee Il Lee,Hae Young Park,Jin Hae Lee,In Tae Kim,Chan Kee Park 대한안과학회 2014 대한안과학회지 Vol.55 No.5

Purpose: To examine retinal nerve fiber layer (RNFL) changes after intravitreal injection of bevacizumab in patients with or without underlying glaucoma. Methods: A total of 104 eyes of 104 patients with retinal disease undergoing intravitreal injection of bevacizumab were prospectively investigated. Bevacizumab injections (1.25/0.05 mg/mL) were performed using a standardized technique. In the patient who had pretreatment with intraocular pressure (IOP)-lowering medication, 1 drop of brimonidine was instilled 30 minutes before the injection. Before and after the intravitreal injections, the patients were monitored for IOP and evaluated with optical coherence tomography using Stratus at least 3 months after the injection. Results: Thirty minutes after injection, 6.4% of patients had an IOP over 30 mm Hg in the non-pretreatment group while no patient had an IOP over 30 mm Hg in the pretreatment group. In eyes with only retinal diseases, the RNFL thickness did not change significantly after the injection regardless of pretreatment, whereas in eyes with underlying glaucomatous damage and no pretreatment, significant decrease in RNFL thickness was observed at the superior (<em>p</em> = 0.036) and temporal (<em>p</em> = 0.048) sectors of the optic nerve head without pretreatment. Conclusions: Intravitreal injection of bevacizumab did not typically cause significant changes in RNFL thickness; however, in eyes with underlying glaucoma without pretreatment, a significant decrease in RNFL thickness was observed in the superior and temporal sectors of the optic nerve head. Therefore, applying IOP-lowering pretreatment medication before intravitreal injection of bevacizumab is required for protection of RNFL in glaucoma patients. J Korean Ophthalmol Soc 2014;55(5):693-701

코헨증후군에서의 안과적 소견

박창현,최경식,이동환.Chang Hyun Park. M.D.. Kyung Seek Choi. M.D.. Dong Hwan Lee. M.D.. Ph.D. 대한안과학회 2006 대한안과학회지 Vol.47 No.4

Purpose: We report two cases of Cohen syndrome associated with ophthalmologic findings, which is the first such report from Korea. Methods: A 14-year-old boy and a 13-year-old girl, a brother and sister, who had visited the department of pediatrics for evaluation of developmental disorders was transferred to the department of ophthalmology due to evidence of nyctalopia and decreased visual acuity. There, refraction, ultrasonography, and fundus examinations were performed. Results: The children had high myopia, and refractive astigmatism. Bull`s eye maculopathy with a pale disc was found on the fundus examination. There were characteristic facial appearances including wave-shaped, down-slanting palpebral fissures and short philtrum. They also had grimacing expressions upon smiling. Neutropenia was identified in the female patient. Conclusions: Cohen syndrome should be suspected and considered in the differential diagnosis of patients with high myopia, nyctalopia, and decreased visual acuity.

산소로 유도된 망막증 모델에서 인간재조합 적혈구생성인자가 망막혈관에 미치는 영향

박창현,박태관,김성신,이승준,온영훈,김성운,Chang Hyun Park,Tae Kwann Park,Seung Joon Lee,Young Hoon Ohn,Sung Woon Kim 대한안과학회 2007 대한안과학회지 Vol.48 No.6

Purpose: To evaluate the effect of recombinant human erythropoietin (rhEPO) on the retinal vessels in a rat model of oxygen-induced retinopathy (OIR). Methods: Twenty-six Sprague-Dawley rat siblings were exposed to seven cycles each of hyperoxia (80% O2, 23.5 hours) and room air recovery (0.5 hours), followed by exposure to room air for five days. After each of the test group and control group was divided into two groups of rhEPO injected group and normal saline injected group, 400 u/kg of rhEPO or normal saline were intraperitoneally injected, respectively on the third, fifth, and eighth days of the experiment. Retinal neovascularization and capillary densities were compared between the rats on the eighth and fourteenth day after injection. The extent of VEGF164, and IGF-1 mRNA expression was measured in the rats on the 14th day post-injection. Results: Neovascularization and capillary density was the most increased in the rhEPO injected test group, but the avascular area was widely distributed in the vicinity of the retina. The degree of VEGF164 mRNA expression was highest in the test group that had been injected with normal saline. We found no difference in IGF-1 mRNA levels between the groups. Conclusions: We can infer that rhEPO can be a potent factor for inducing retinal neovascularization.

열공망막박리에서 냉동고정술과 도상검안경레이저광응고술의 결과 비교

박창현,박성희,이성진,Chang Hyun Park,M,D,Song Hee Park,M,D,Ph,D,Sung Jin Lee,M,D,Ph,D 대한안과학회 2008 대한안과학회지 Vol.49 No.11

Purpose: To compare the efficacy and safety of intraoperative laser indirect ophthalmoscopy and cryopexy for rhegmatogenous retinal detachment through the use. Methods: We retrospectively analyze the clinical results of 60 patients (61 eyes) with rhegmatogenous retinal detachment. All eyes had an attached macula and were scheduled for conventional scleral buckling surgery with cryopexy (25 eyes) or laser indirect ophthalmoscopy (36 eyes) from March 2001 to August 2007. The visual acuities of the two groups at the first postoperative day, 1 week, 1 month, and 3 months were compared. Retinal reattachment, macular pucker, cystoid macular edema, and proliferative vitreoretinopathy were confirmed 3 months after surgery. Results: The visual recovery was faster in patients who received laser indirect ophthalmoscopy (1 day, P=0.044; 1 week, P=0.017). During the follow-up period, anatomical failure in the laser indirect ophthalmoscopy group did not develop, but there were two anatomical failures in the cryopexy group. In addition, 1 PVR was detected in the cryopexy group. However, neither group exhibited macular pucker or cystoid macular edema. Postoperative additional laser photocoagulation was performed on 7 eyes (19.4%) in thelaser indirect ophthalmoscopy group and 2 eyes (4.0%) in the cryopexy group. Conclusions: Although intraoperative laser indirect ophthalmoscopy causes less chorioretinal scar formation than cryopexy, it has a higher anatomical success rate and allows for faster visual recovery. J Korean Ophthalmol Soc 2008;49(11):1779-1784

분산 감소 기법에 의한 몬테칼로 선량 계산 효율 평가

박창현,박성용,박달,Park, Chang-Hyun,Park, Sung-Yong,Park, Dal 한국의학물리학회 2003 의학물리 Vol.14 No.4

몬테칼로 계산은 다른 어떤 알고리즘보다 정확한 선량 계산 결과를 주지만 계산 시간이 오래 걸리는 단점이 있다. 본 연구에서는 Varian 600 C/D 선형가속기로부터지 6 MV 광자선에 대해 몬테칼로 계산을 사용하여 얻은 선량 분포가 측정에 의해 얻은 선량 분포와 2% 이내에서 서로 잘 일치하도록 하며 분산 감소 기법을 사용하여 계산 시간 단축 정도를 평가하였다. 그리고 연산 능력을 높여 계산 시간 단축 정도를 평가하여 분산 감소 기법을 사용한 경우와 연산 능력을 높인 경우 간에 계산 시간 단축 정도를 비교하였다. 몬테칼로 계산 코드로는 빔 모사를 위해 BEAMnrc 코드, 선량 계산을 위해 DOSXYZnrc 코트를 각각 사용하였는데 분산 감소 기법은 이 코드들에서 지원하는 방법들을 사용하였고 연산 능력을 높이는 방법으로는 컴퓨터 클러스터를 이용한 병렬 처리를 사용하였다. 비교 결과, 분산 감소 기법을 사용하여 계산 시간을 최대 1/25 이상 단축시킬 수 있었고 9대의 컴퓨터를 이용한 병렬 처리 결과 계산 시간을 1/9로 단축시킬 수 있었다. 계산 곁과의 정확성을 만족할 만한 수준으로 유지할 수 있다면 분산감소 기법을 포함한 간략화된 물리의 적용은 현 시점에서 몬테칼로 선량 계산 시간을 획기적으로 단축시킬 대안이 될 수 있다. The Monte Carlo calculation is the most accurate means of predicting radiation dose, but its accuracy is accompanied by an increase in the amount of time required to produce a statistically meaningful dose distribution. In this study, the effects on calculation time by introducing variance reduction techniques and increasing computing power, respectively, in the Monte Carlo dose calculation for a 6 MV photon beam from the Varian 600 C/D were estimated when maintaining accuracy of the Monte Carlo calculation results. The EGSnrc­based BEAMnrc code was used to simulate the beam and the EGSnrc­based DOSXYZnrc code to calculate dose distributions. Variance reduction techniques in the codes were used to describe reduced­physics, and a computer cluster consisting of ten PCs was built to execute parallel computing. As a result, time was more reduced by the use of variance reduction techniques than that by the increase of computing power. Because the use of the Monte Carlo dose calculation in clinical practice is yet limited by reducing the computational time only through improvements in computing power, introduction of reduced­physics into the Monte Carlo calculation is inevitable at this point. Therefore, a more active investigation of existing or new reduced­physics approaches is required.

단안 분지망막정맥폐쇄 환자의 무증상 반대안에서 안구관류압의 일중변동

박창현,박혜영,윤재윤,박찬기,Chang Hyun Park,Hae Young Park,Jae Yoon Yoon,Chan Kee Park 대한안과학회 2014 대한안과학회지 Vol.55 No.2

Purpose: To investigate diurnal change in blood pressure (BP), intraocular pressure (IOP), and ocular perfusion pressure (OPP) in patients with unilateral branch retinal vein occlusion (BRVO) and compare the results with healthy controls. Methods: We conducted a prospective case‐control study which included 50 patients with unilateral BRVO and 50 agematched volunteers as controls. Each participant underwent a comprehensive ophthalmic examination including optical coherence tomography (OCT). BP and IOP were evaluated 4 times daily at 8 AM, 10 AM, 2 PM and 6 PM. The mean and fluctuation of BP, IOP, mean arterial pressure (MAP), mean OPP (MOPP), and diastolic OPP (DOPP) were compared between fellow eyes of BRVO patients and normal control eyes. Results: The average retinal nerve fiber layer (RNFL) thickness was significantly reduced in the fellow eyes of BRVO patients compared to control eyes (p < 0.001). Mean IOP and IOP fluctuation did not differ, but BP fluctuation (systolic BP fluctuation, p = 0.045; diastolic BP fluctuation, p = 0.037) and MAP fluctuation (p = 0.011) were greater in the fellow eyes of BRVO patients compared to normal eyes. The mean MOPP and DOPP did not differ between groups, however, the fluctuation of MOPP (p < 0.001) and DOPP (p < 0.001) were significantly increased in the fellow eyes of BRVO patients. The mean and fluctuation of BP, MAP, MOPP and DOPP were associated with reduced average RNFL thickness in the fellow eyes of BRVO patients. Conclusions: These results suggest the fellow eyes of unilateral BRVO patients may be at risk of developing glaucomatous damage. J Korean Ophthalmol Soc 2014;55(2):237-246

기아 마우스 담세관의 전자현미경적 연구

박창현,신영철,장병준,Park, Chang-Hyun,Shin, Young-Chul,Jang, Byung-Joon 한국현미경학회 1996 Applied microscopy Vol.26 No.2

This study was designed to investigate the ultrastructural alterations of the hepatocyte and bile canaliculus of the fasted mice with transmission and scanning electron microscopes. The morphometry was also carried out for the caliber of the bile canaliculus and the number, length and thickness of the microvillus. The hepatocyte observed in the three day fasting group showed ultrastructural images of active function. The dilated bile canaliculi, especially of type II were increased in number as compared with those seen in the normal group. However, the hepatocyte observed in the six day fasting group showed ultrastructural images of inactive function. The bile canaliculi without dilation (type I) were increased in number. The number of microvilli were identical with one another among the different types of bile canaliculi, while their length and thickness were reduced in the dilated bile canaliculi. From the evidence, the luminal size of the bile canaliculi seems to be easily changeable according to the functional state of the hepatocyte. However, the microvilli may not be changed in number but may be changed length and thickness when the bile canaliculi are dilated.

근사최적화 기법을 이용한 RC 빌딩의 구조 최적설계

박창현,안희재,최동훈,정철규,Park, Chang-Hyun,Ahn, Hee-Jae,Choi, Dong-Hoon,Jung, Cheul-Kyu 한국전산구조공학회 2011 한국전산구조공학회논문집 Vol.24 No.2

본 논문에서는 수직하중, 풍하중 및 지진하중에 의해 발생하는 변위 관련 구속조건을 만족하면서 RC(Reinforced Concrete) 빌딩 구조의 부피를 최소화하기 위한 설계문제를 정식화하였다. 구조해석 절차 자동화의 어려움으로 인해 실험 계획법과 근사화기법, 최적화기법을 이용한 근사모델기반 최적설계를 수행하였다. 특히, 만족할 만한 설계 결과를 얻을 때까지 설계변수의 범위와 구속조건의 허용값을 조정하는 단계적 최적설계 방법을 제안하였다. 제안된 단계적 최적설계 방법을 통해 주어진 구속조건을 모두 만족하면서 RC 빌딩 구조의 부피를 초기 설계 대비 53.3% 감소시키는 결과를 얻음으로 써 본 논문에서 보인 단계적 최적설계 방법의 타당성을 보였다. A design optimization problem was formulated to minimize the volume of an RC building structure while satisfying design constraints on structural displacements under vertical, wind and seismic loads. We employed metamodel-based design optimization using design of experiments, metamodeling and optimization algorithm to circumvent the difficulty of the automation of structural analysis procedure. Especially, we proposed a design approach of repetitive design optimizations by stages with changing the side constraint values on design variables and limit values on design constraints until a satisfactory design result was obtained. Using the proposed design approach, the volume of the RC building structure has been reduced by 53.3 % compared to the initial one while satisfying all the design constraints. This design result clearly shows the validity of the proposed design approach.

지상파 DMB용 능동형 안테나의 설계 및 제작

박창현,신동률,김정표,김기호,양묘근,성원모,Park, Chang-Hyun,Shin, Dong-Ryul,Kim, Jeong-Pyo,Kim, Gi-Ho,Yang, Myo-Guen,Seong, Won-Mo 한국전자파학회 2007 한국전자파학회논문지 Vol.18 No.1

본 논문에서는 기생 소자를 이용한 소형화된 안테나와 저 잡음 증폭기를 결합하여 휴대 단말기에 적용이 가능한 지상파 DMB 능동형 안테나를 설계 및 제작하였다. 제작된 능동형 안테나의 크기는 $80{\times}6{\times}0.4\;mm$로서 FR4 기판으로 제작하였다. 제작된 안테나는 기생 소자 및 단락 스터브가 없는 단순 안테나에 비해 38.8 %의 안테나 크기 축소 효과를 가진다. 제작된 능동 안테나를 DMB 수신 모듈에 연결하여 S/N 비를 측정한 결과 300 mm의 로드 안테나와 동등 이상의 성능을 나타내었다. 본 논문에서 제작된 능동형 안테나는 지상파 DMB 휴대 단말기에 적용 가능하다. In this paper, An active antenna of T-DMB was developed to equip to handhold gadgets by using LNA and a parasitic element allowing to miniature. The size of the fabricated active antenna is $80{\times}6{\times}0.4\;mm$ and FR4 is used for the substrate. The size of the proposed antenna is reduced by 38.8% at the operating frequency compared to one without a parasitic element, and a short stub. The proposed antenna shows improved performance at the measurement especially in the ratio of S/N compared with conventional monopole of 300 mm. The proposed antenna is well able to adapt into handhold gadgets for receiving T-DMB.

중량 최소화를 위한 RC 빌딩의 구조 최적설계

박창현,안희재,최동훈,정철규,Park, Chang-Hyun,Ahn, Hee-Jae,Choi, Dong-Hoon,Jung, Cheul-Kyu 한국전산구조공학회 2010 한국전산구조공학회논문집 Vol.23 No.5

본 논문에서는 중력하중 및 풍하중, 지진하중을 받는 지상 8층, 지하 3층의 RC(Reinforced Concrete) 빌딩 시공에 필요한 부재의 재료비를 줄이기 위해 중량을 감소시키는 구조 최적설계를 수행한다. 이를 위해 설계요구사항을 바탕으로 부재의 부피를 최소화하는 설계변수값을 찾기 위한 설계문제를 정식화한다. 최적설계 수행을 위해 상용 PIDO(Process Integration and Design Optimization) 툴인 PIAnO(Process Integration, Automation and Optimization)에서 제공하는 다양한 설계기법들을 이용한다. 먼저 실험계획법(Design of Experiments; DOE)을 이용하여 실험계획을 세우고, 실험점에 따라 건축분야 범용 구조해석 프로그램인 MIDAS Gen을 사용하여 구조해석을 수행한다. 그리고 해석결과를 바탕으로 각 응답에 대한 근사모델을 생성한 후 근사모델의 예측성능을 평가한다. 예측성능이 검증된 근사모델과 최적화기법을 이용하여 최적설계를 수행하고, 설계조건을 만족하면서 부재의 부피를 최소화하는 최적 설계변수값을 도출함으로서 본 논문에서 제안된 설계방법의 유효성을 보이고자 한다. Structural optimization is performed to minimize the weight of a RC building structure, which has eight floors above ground and three underground, under gravity, wind, and seismic loads. Design optimization problem is formulated to find the values of the design variables that minimize the volume while satisfying various design and side constraints. To solved the optimization problem posed, several design techniques equipped in PIAnO, a commercial PIDO tool, are used. DOE is used to generate training points and structural analysis is performed using MIADS Gen, a general-purpose structural analysis CAE tool. Then, meta-models are generated from structural analysis results and accuracies of meta-models are evaluated. Next, design optimization is performed by using the verified meta-models and optimization technique equipped in PIAnO. Finally, we obtained optimal results, which could demonstrate the effectiveness of our design method.