Comparison of Cytotoxic Effects on Rabbit Corneal Endothelium between Preservative-free and Preservative-containing Dorzolamide/ timolol

권준기,허정화,김효명,송종석 대한안과학회 2015 Korean Journal of Ophthalmology Vol.29 No.5

Purpose: To evaluate and compare the toxic effects of eyedrops containing a fixed combination of 2.0% dorzolamide and 0.5% maleate timolol with or without preservatives on rabbit corneal endothelium. Methods: This study was performed with 22 eyes of New Zealand white rabbits. Dorzolamide/timolol eyedrops with preservative (Cosopt group) or without preservative (Cosopt-S group) were diluted with a balanced salt solution at a 1 : 1 ratio. We injected 0.1 mL of diluted Cosopt into the anterior chamber of left eyes and an equal volume of diluted Cosopt-S into the anterior chamber of right eyes. Corneal thickness, corneal haze, and conjunctival injection were measured before and 24 hours after treatment. Endothelial damage was compared between both eyes by vital staining (alizarin red/trypan blue staining), live/dead cell assay, TUNEL assay, and scanning electron microscopy. Results: Corneal endothelial damage was severe in the Cosopt group. Cosopt-treated eyes exhibited remarkable corneal edema and prominent apoptosis of endothelial cells. In addition, the live/dead cell assay revealed many dead cells in the endothelium, and scanning electron microscopy analysis showed that corneal endothelial cells exhibited a partial loss of microvilli on the surface as well as extensive destruction of intercellular junctions. However, in the Cosopt-S group, corneal edema was mild and the damage to the corneal endothelium was minimal. Conclusions: The main cause of corneal endothelial toxicity was due to the preservative in the dorzolamide/ timolol fixed combination eyedrops, and not the active ingredient. Thus, it appears to be safer to use preservative- free eyedrops during the early postoperative period.

삼차원(3D) 영상 시청이 눈 피로에 미치는 영향

권준기,강수연,김균형,서영우,오재령,김승현,김효명,송종석 대한안과학회 2012 대한안과학회지 Vol.53 No.7

Purpose: To compare ocular fatigue, non-ocular symptoms, and ocular surface changes, such as tear break-up time (BUT) and ocular surface temperature, after watching 2-dimensional (2D) and 3-dimensional (3D) images. Methods: Fourteen volunteers were enrolled in the present study. Subjects watched 2D as well as 3D images and answered questions regarding ocular fatigue and general symptoms such as headache. Before and after watching images, the spherical equivalent, degree of conjunctival injection, tear BUT, and ocular surface temperature were measured and the amount of change was analyzed. While watching images, subjects answered questions regarding ocular fatigue and the time when they began to feel definitive symptoms. Results: Watching 3D images induced a greater degree of ocular fatigue, headache, and decreasing concentration than watching 2D images (p = 0.038, 0.003, and 0.045, respectively). While watching images, 3D images induced a greater degree of ocular fatigue than 2D images and caused subjects to feel earlier ocular fatigue (3D: 54.86 min, 2D: 78.57 min, p = 0.002). Spherical equivalents became more myopic after watching 3D images. Conclusions: After watching 3D images, a greater degree of ocular fatigue, headache, and decreasing concentration was induced and a shorter time to feel definitive ocular fatigue was observed than after watching 2D images. In addition, spherical equivalents changed myopically after watching 3D images. J Korean Ophthalmol Soc 2012;53(7):941-946

눈물점 협착 환자에서 고주파 수술기구를 이용한 눈물점 성형술의 효과

권준기,장민욱,백세현,이태수,Jun Ki Kwon,MD,Min Wook Chang,MD,PhD,Se Hyun Baek,MD,PhD,Tae Soo Lee,MD,PhD 대한안과학회 2012 대한안과학회지 Vol.53 No.12

Purpose: To introduce and assess the results of punctoplasty using a radiofrequency surgical unit for punctal stenosis. Methods: Patients who complained of epiphora, had an intact lacrimal pathway below puncti, and underwent punctoplasty with the Ellman Surgitron F.F.P.F were evaluated in the present study. Results: A total of 19 patients (31 eyes) were included in the study. The average age was 55 years (±15.7 years). At the last follow-up visit, 27 eyes (87%) had patent puncti, 1 eye became stenotic again, and 3 eyes were completely obstructed. Twenty-two eyes (71%) showed almost complete disappearance of dye on the fluorescein dye-disappearance test (FDDT). Twenty-five eyes (81%) had symptomatic improvement. No significant complication was reported postoperatively. Conclusions: Punctoplasty with a radiofrequency surgical unit is a simple and effective method for punctal stenosis.

식품 미생물 균총 연구를 위한 최신 마이크로바이옴 분석 기술

권준기(Joon-Gi Kwon),김선균(Seon-Kyun Kim),이주훈(Ju-Hoon Lee) 한국식품과학회 2019 식품과학과 산업 Vol.52 No.3

Rapid development of next-generation sequencing (NGS) technology is available to study microbes in genomic level. This NGS has been widely used in DNA/RNA sequencing for genome sequencing, metagenomics, and transcriptomics. The food microbiology area could be categorized into three groups. Food microbes including probiotics and food-borne pathogens are studied in genomic level using NGS for microbial genomics. While food fermentation or food spoilage are more complicated, their genomic study needs to be done with metagenomics using NGS for compositional analysis. Furthermore, because microbial response in food environments are also important to understand their roles in food fermentation or spoilage, pattern analysis of RNA expression in the specific food microbe is conducted using RNASeq. These microbial genomics, metagenomics, and transcriptomics for food fermentation and spoilage would extend our knowledge on effective utilization of fermenting bacteria for health promotion as well as efficient control of food-borne pathogens for food safety.

축산식품 미생물 유전체 연구를 위한 차세대 염기서열(NGS) 분석 및 활용 기술

김유태,권준기,이요셉,이주훈,Kim, You-Tae,Kwon, Joon-Gi,Lee, Jo-Seph,Lee, Ju-Hoon 한국축산식품학회 2020 축산식품과학과 산업 Vol.9 No.2

LiDAR 항공측량에 의한 곶자왈의 분포와 범위 설정

김진광,권준기,최형순 국토지리학회 2015 국토지리학회지 Vol.49 No.4

This study is intended to set up a distribution and extent of area that Gotjawal made of volcanic activity of the island. Gotjawal is rugged Gotjawal is rugged area of volcanic rock made of high-viscosity lavas that split into various size. And later, forest cover its surface. Gotjawal is a natural evergreen coniferous forests. And it is a genetic-resource repository of plants and animals in Jeju, contains a large amount of underground water also. It is distributed from middle mountainous area of Hallasan to coastal, it help to live animals and plants as buffer zone. Initial investigation has been set up primarily to distribution, characteristics and the scope of the soil. But there are limits in setting the specific area because it was made mainly fieldwork. In order to prevent reckless development and establish proper development plan at Gotjawal, as natural resource. we select the two site in four candidates, tried to set a precise boundary of Gotjawal using airborne LiDAR and aero digital camera. When existing boundary compared with the results of study, area of Gotjawal was reduced from 58km2 to 49.56km2. The causes were confirmed by golf course, residential, residential land development. 본 연구는 제주도의 화산활동으로 이루어진 곶자왈 지역의 분포와 범위를 설정하고자 하는 것이다. 곶자왈 지역은 화산분출 시 점성이 높은 용암이 크고 작은 암괴로 쪼개지면서 울퉁불퉁한 지형을 이루고 있으며, 그 위에 숲이 형성된 독특한 지역이다. 곶자왈은 상록활엽수림이 천연적으로 자생하고 있는 지역으로서 제주지역 동식물 유전자원의 보고이며, 지하수함양 역할을 하고 있는 곳이다. 이와 같이 곶자왈의 중요성을 인지하여 조사 초기에는 주로 토양의 분포나 특성, 그리고 범위를 설정하는데 주로 현지조사로만 이루어져 명확한 영역을 설정하는데 한계가 있었다. 자연자원인 곶자왈에 대한 난개발을 방지하고 정확한 개발계획을 세울 수 있도록 하기 위해 4곳의 곶자왈 중 두 곳에 대해 항공 LiDAR 장비와 항공 디지털카메라를 활용하여 정밀한 곶자왈의 경계를 설정하고자 하였다. 연구 결과 기존 경계와 비교를 하였을 때 58km2에서 49.56km2로 곶자왈의 면적이 줄어들었다. 원인은 골프장, 주거지, 택지개발에 의한 것으로 확인되었다.

백내장수술 후 독성 전안부 증후군으로 인한 동공차단의 증례

민찬홍,권준기 대한안과학회 2019 대한안과학회지 Vol.60 No.8

Purpose: We report a case of pseudophakic pupillary block after toxic anterior segment syndrome (TASS). Case summary: An 84-year-old woman underwent phacoemulsification and intraocular lens implantation in the posterior chamber. Six days after surgery, anterior chamber inflammation was seen. Twenty-five days after surgery, a sudden increase in intraocular pressure (IOP) associated with pupillary block was observed. Despite the use of IOP-lowering medication, the IOP was not controlled. Peripheral laser iridotomy failed. After surgical peripheral iridectomy, IOP decreased significantly and was controlled. Conclusions: Despite the rarity of TASS combined with pseudophakic pupillary block, clinicians must be aware of this condition in patients showing prolonged inflammatory state and IOP elevation after surgery. 목적: 백내장수술 후 발생한 독성 전안부 증후군으로 인한 동공차단의 증례를 보고하고자 한다. 증례요약: 84세 여성환자에게 수정체유화술로 백내장을 제거한 후 수정체낭에 인공수정체를 삽입하였다. 수술 후 특별한 문제는 없었으나 6일째 전방 염증 증가 소견을 보였으며, 25일 뒤에 동공차단이 발생하며 안압이 상승하였다. 안압 조절을 위한 안압하강제를 사용하였으나 효과가 적었으며, 주변부 레이저 홍채절개술을 시행하고자 하였으나 실패하였다. 수술적으로 홍채절제술을 시행하고 안압은 조절되었다. 결론: 백내장수술을 하는 경우에 드문 독성 전안부 증후군과 동공차단의 가능성을 고려해야 할 것으로 생각한다.

Additive Role of Optical Coherence Tomography Angiography Vessel Density Measurements in Glaucoma Diagnoses

권혜지,성경림,권준기 대한안과학회 2019 Korean Journal of Ophthalmology Vol.33 No.4

Purpose: This study compared the glaucoma diagnostic abilities of optical coherence tomography (OCT) andoptical coherence tomography angiography (OCTA). In addition, the possibility of enhancing diagnostic capabilityby combining the two modalities was investigated. Methods: A total of 131 healthy eyes and 113 glaucomatous eyes were imaged by both OCT and OCTA. InOCT, glaucoma was defined as when the color of the superior or inferior quadrant of the peripapillary retinalnerve fiber layer thickness map was yellow (borderline, <5%) or red (outside normal limits, <1%). In OCTA,glaucoma was determined using the cut-off value of the superior or inferior peripapillary vessel density, calculatedafter receiver operating characteristic curve analysis. Sensitivity and specificity were determined by OCTalone, by OCTA alone, or by OCT and OCTA combined. Results: The sensitivity of OCT (86.7%) was better than that of OCTA (74.3%), whereas the specificity of OCTA(87.0%) was better than that of OCT (67.9%). When these two modalities were combined, both sensitivity andspecificity were enhanced (90.3% and 92.4%, respectively). Among the 131 eyes, 32 were misdiagnosed asglaucomatous by OCT but accurately diagnosed as normal by OCTA. These eyes were myopic, with a longeraxial length and a thinner and temporally displaced peak of peripapillary retinal nerve fiber layer thickness,causing the false positive result in OCT. Conclusions: When OCTA was combined with OCT, the specificity of glaucoma diagnoses were enhanced. OCTA may compensate for the shortcomings of OCT in the diagnosis of glaucoma.

수경재배용 전기전도도 및 pH 전극 온도 보상 회로 설계

한희조 ( Hee-jo Han ),조우재 ( Woo-jae Cho ),권준기 ( Jun-ki Gwon ),김학진 ( Hak-jin Kim ),정대현 ( Dae-hyun Jung ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.2

수경재배에서 작물에게 관수되는 양액은 pH와 EC (Electrical Conductivity, 전기전도도)를 기반으로 제어가 이루어진다. 양액의 온도가 바뀌게되면 양액 내 이온의 활성도가 변화게 되어 측정된 pH와 EC 값이 자동 제어기반의 관수 시스템의 오차로 작용하여 잘못된 EC, pH 값을 가진 양액의 조성을 야기 할 수 있다. 본 연구에서는 최종적으로 온도 보상이 가능한 pH/EC 측정시스템을 개발하기 위하여 온도에 의해 영향을 받은 양액 센서 신호를 기준온도(25°C)에서의 신호 값으로 보정 유지 할 수 있는 회로와 관련 알고리즘을 개발하여 그 효과를 실험적으로 구명하고자 하였다. 온도측정은 기존 상용시스템과 같이 NTC(Negative Temperature Coefficient) 써미스터를 이용하였다. EC, pH 센서의 온도영향 반응성은 양액 농도범위인 EC 0.5~2.5 ds/m이고, pH 5.0~7.0에 대해 각각 5개씩 용액을 제작하여 농도 범위에서 양액 센서의 온도 반응 특성 곡선을 구하였다. 이때 나타난 온도 반응 특성에 맞추어 NTC 기반의 OP amp 회로를 설계하고 이에 대한 전달함수를 기반으로 온도 보상회로의 증가 값을 결정하는 저항 소자들에 대해 각각 100Ω 단위로 저항값을 변화시키면서 각 용액의 농도별로 보상 후의 신호 값과 기준온도에서의 신호 값의 차이의 평균제곱근편차(RMSD)를 구하였다. 전체 용액 구간에서 가장 낮은 RMSD를 갖는 저항소자를 결정하는 연산식을 구성한 뒤 이를 기반으로 주어진 양액 센서의 온도 반응 특성에 대해 가장 보상성능이 우수한 회로를 구성하였다. 최적화된 온도 보상회로를 기반으로 양액 센서에 대해 온도에 따른 신호값을 측정하고 이를 온도 보상회로 적용 전의 신호와 RMSD를 비교한 결과 RMSD가 줄어들면서 온도 보상이 이루어짐을 확인하였다.