Clinical Outcomes of an Optimized Prolate Ablation Procedure for Correcting Residual Refractive Errors Following Laser Surgery

Byunghoon Chung,Hun Lee,Bong Joon Choi,Kyung Ryul Seo,Eung Kwon Kim,Dae Yune Kim,Tae-im Kim 대한안과학회 2017 Korean Journal of Ophthalmology Vol.31 No.1

Purpose: The purpose of this study was to investigate the clinical efficacy of an optimized prolate ablation procedure for correcting residual refractive errors following laser surgery. Methods: We analyzed 24 eyes of 15 patients who underwent an optimized prolate ablation procedure for the correction of residual refractive errors following laser in situ keratomileusis, laser-assisted subepithelial keratectomy, or photorefractive keratectomy surgeries. Preoperative ophthalmic examinations were performed, and uncorrected distance visual acuity, corrected distance visual acuity, manifest refraction values (sphere, cylinder, and spherical equivalent), point spread function, modulation transfer function, corneal asphericity (Q value), ocular aberrations, and corneal haze measurements were obtained postoperatively at 1, 3, and 6 months. Results: Uncorrected distance visual acuity improved and refractive errors decreased significantly at 1, 3, and 6 months postoperatively. Total coma aberration increased at 3 and 6 months postoperatively, while changes in all other aberrations were not statistically significant. Similarly, no significant changes in point spread function were detected, but modulation transfer function increased significantly at the postoperative time points measured. Conclusions: The optimized prolate ablation procedure was effective in terms of improving visual acuity and objective visual performance for the correction of persistent refractive errors following laser surgery.

래더링 기법을 이용한 교육서비스제품의 가치구조 파악에 대한 연구

임병훈 ( Lim Byunghoon ),정선태 ( Chung Suntae ) 인하대학교 교육연구소 2007 교육문화연구 Vol.13 No.1

The purpose of this study is to select consumers of lifelong education for the research scope, to analyze their motives classified into attribute, consequences, and personal value, and to promote consumption of education services. This study has questioned the followings to achieve the purpose of the research. < Question 1 > : How is the value system of the consumers constructed? < Question 2 > : What meaning do the effects found in the principal values have? The result of this study can be used in management of lifelong education service institutions from many angles. Secondly, it can supply materials for setting up visions and missions of lifelong education service institutions when they try to establish a management strategy. Thirdly, it can help establishment of marketing communication strategy, that is, we can set the priority and the direction of marketing mix through users' cognitive structures and we can know the appeal concept of advertisement and marketing messages. Besides we can get lots of hints how to attract consumers' attention. Through this study, lifelong education service institutions should create messages that can be appealed to the value such as self-realization and self-respect.

TCP Vegas의 공정성 향상을 위한 혼잡 제어 알고리즘

오민철(Mincheol Oh),송병훈(Byunghoon Song),정광수(Kwangsue Chung) 한국정보과학회 2004 정보과학회논문지 : 정보통신 Vol.31 No.3

인터넷의 안정성에 가장 큰 영향을 미치는 요소는 종단간에 이루어지는 TCP 혼잡제어이다. 현재 인터넷의 주요 TCP 버전인 Reno가 사용하는 수동적인 혼잡제어 방법은 네트워크의 혼잡을 심화시키는 원인이 된다. 이러한 Reno의 문제점을 개선하기 위해 제안된 Vegas는 Reno에 비해 우수한 성능을 가짐이 증명되었음에도 불구하고 두 가지 심각한 불공정성 문제를 가지고 있기 때문에 범용적으로 사용되지 못하고 있다. 본 논문에서는 이러한 Vegas의 문제점을 보완하기 위해서 기존의 Vegas 혼잡제어 알고리즘을 개선한 새로운 TCP PowerVegas 혼잡제어 알고리즘을 제안한다. rtt(round trip time)만을 기반으로 네트워크의 혼잡을 제어하는 기존의 Vegas에 비해서 제안한 PowerVegas는 rtt와 패킷 손실 정보를 유기적으로 결합 시킨 새로운 기법으로 경쟁력 있는 혼잡제어를 수행한다. 그러므로 기존의 Vegas에서 발생했던 불공정성 문제를 모두 효과적으로 개선할 수 있다. 제안한 알고리즘의 성능을 검증하기 위해 동일한 시뮬레이션 환경에서 PowerVegas와 Reno 및 Vegas를 비교하는 실험을 수행하였다. 실험 결과를 통해서 제안한 PowerVegas가 기존 Reno의 혼잡제어 방법에 비해 우수한 성능을 보일 뿐만 아니라, Vegas의 불공정성 문제도 크게 개선되었음을 확인할 수 있었다. The most important factor influencing the robustness of the Internet is the end-to-end TCP congestion control. However, the congestion control scheme of TCP Reno, the most popular TCP version on the Internet, employs passive congestion indication. It makes worse the network congestion. Recently, Brakmo and Peterson have proposed a new version of TCP, which is named TCP Vegas, with a fundamentally different congestion control scheme from that of the Reno. Many studies indicate that the Vegas is able to achieve better throughput and higher stability than the Reno. But there are two unfairness problems in Vegas. These problems hinder the spread of the Vegas in current Internet. In this paper, in order to solve these unfairness problems, we propose a new congestion control algorithm called TCP PowerVegas. The existing Vegas depends mainly only on the rtt(round trip time), but the proposed PowerVegas use the new congestion control scheme combined the information on the rtt with the information on the packet loss. Therefore the PowerVegas performs the congestion control more competitively than the Vegas. Thus, the PowerVegas is able to solve effectively these unfairness problems which the Vegas has experienced. To evaluate the proposed approach, we compare the performance among PowerVegas, Reno and Vegas under same network environment. Using simulation, the PowerVegas is able to achieve better throughput and higher stability than the Reno and is shown to achieve much better fairness than the existing Vegas.

TCP Power Vegas

오민철(Mincheol Oh),송병훈(Byunghoon Song),정광수(Kwangsue Chung) 한국통신학회 2003 한국통신학회 학술대회 및 강연회 Vol.2003 No.4

NewVegas : 공정성 향상을 위한 새로운 TCP Vegas 알고리즘

이선헌(Sunhun Lee),송병훈(Byunghoon Song),정광수(Kwangsue Chung),이승형(Seung Hyong Rhee),최웅철(WoongChul Choi) 한국통신학회 2004 한국통신학회 학술대회 및 강연회 Vol.2004 No.4

100 MVA STATCOM 개발

한영성(Youngseong Han),정정주(Chung Choo Chung),박용희(Yonghee Park),김준성(Junsung Kim),유현호(Hyunho Yoo),최종윤(Jongyun Choi),서인영(Inyoung Suh),장병훈(Byunghoon Chang) 전력전자학회 2009 전력전자학술대회 논문집 Vol.2009 No.1

한전 전력연구원이 주관하고 (주)효성이 참여하는 협동 연구의 형태로 진행된 연구과제의 결과물로써 100 MVA STATCOM 이 설계, 제작되었다. 100 MVA STATCOM은 순수 국내 기술로 설계, 제작되었으며, 한전 미금변전소 345 ㎸에 연결되어 Commissioning 중에 있다.

TCP Vegas에서 공정성 향상을 위한 혼잡제어 알고리즘

이선헌(Sunhun Lee),송병훈(Byunghoon Song),정광수(Kwangsue Chung) 한국정보과학회 2005 정보과학회논문지 : 정보통신 Vol.32 No.5

인터넷의 안정성에 영향을 미치는 요소로 종단간에 이루어지는 TCP 혼잡제어가 있다. 현재 인터넷의 주요 TCP 버전인 Reno가 사용하는 수동적인 혼잡제어 방법은 네트워크의 혼잡을 심화시키는 원인이 된다. 그러나 이러한 Reno의 문제점을 개선하기 위해 제안된 Vegas는 Reno에 비해 우수한 성능을 가짐이 이전의 관련 연구에서 증명되었음에도 불구하고 세 가지 심각한 불공정성 문제를 가지고 있기 때문에 범용적으로 사용되지 못하고 있다. 본 논문에서는 이러한 Vegas의 문제점을 보완하기 위해서 기존의 Vegas 혼잡제어 알고리즘을 개선한 새로운 TCP NewVegas 혼잡제어 알고리즘을 제안한다. 제안한 NewVegas는 병목구간 라우터에서 큐잉되는 패킷의 편차를 사용하여 기존 Vegas의 불공정성 문제를 효과적으로 해결한다. 제안한 알고리즘의 성능을 검증하기 위해 NewVegas와 Reno 및 기존의 Vegas를 비교하는 실험을 수행하였다. 실험 결과를 통해서 제안한 NewVegas가 기존 Vegas의 혼잡제어 방법에 비해 우수한 성능을 보일 뿐만 아니라, Vegas의 불공정성 문제도 크게 개선되었음을 확인할 수 있었다. An important factor influencing the robustness of the Internet is the end-to-end TCP congestion control. However, the congestion control scheme of TCP Reno, the most popular TCP version on the Internet, employs passive congestion indication. It makes the network congestion worse. Brakmo and Peterson proposed a congestion control algorithm, TCP Vegas, by modifying the congestion avoidance scheme of TCP Reno. Many studies indicate that Vegas is able to achieve better throughput and higher stability than Reno. But there are three unfairness problems in Vegas. These problems hinder the spread of Vegas in the current Internet. In this paper, in order to solve these unfairness problems, we propose a new congestion control algorithm called TCP NewVegas. The proposed NewVegas is able to solve these unfairness problems effectively by using the variation of the number of queued packets in a bottleneck router. To evaluate the proposed approach, we compare the performance among NewVegas, Reno and Vegas. Through the simulation, NewVegas is shown to be able to achieve throughput and better fairness than Vegas.

Anti–Vascular Endothelial Growth Factor with Gas for Submacular Hemorrhage

Shin, Joo Youn,Choi, Hun Jin,Chung, Byunghoon,Choi, Moonjung,Lee, Jonghyun,Byeon, Suk Ho Lippincott, Williams Wilkins 2016 Optometry and vision science Vol.93 No.2

<P>Purpose. To investigate the treatment outcome of pneumatic displacement and intravitreal anti-vascular endothelial growth factor (VEGF) for submacular hemorrhage (SMH) from exudative age-related macular degeneration (AMD). Methods. Best-corrected visual acuity (BCVA) and central foveal thickness (CFT) were measured at baseline and at 1, 3, and 6 months after initial treatment in 72 eyes of 72 patients treated with a combination of pneumatic displacement and anti-VEGF injection for SMH from exudative AMD. Results. Best-corrected visual acuity and CFT showed significant improvement from baseline during the 6-month follow-up period (logarithm of the minimum angle of resolution BCVA from 1.80 to 1.00, CFT from 886 to 383 mu m, p < 0.001, respectively). The decrease in subretinal hemorrhage was greater than that in subretinal pigment epithelial hemorrhage at 1 month after initial treatment (p < 0.001). In eyes with symptoms for less than 30 days, higher reflectivity of hemorrhage on optical coherence tomography and higher CFT were associated with lower BCVA after 6 months of treatment (reflectivity B = 0.335, p = 0.007; CFT B = 0.001, p = 0.003). Conclusions. The combination of pneumatic displacement and intravitreal anti-VEGF is a useful treatment option for SMH secondary to AMD. Higher baseline CFT and higher reflectivity of hemorrhage were associated with lower BCVA 6 months after initial treatment.</P>

복합 태양열 해수담수기의 변수별 성능실험

여세동(Sedong Yeo),정경열(Kyung-Yul Chung),안병훈(Byunghoon Ahn),박창대(Chang-Dae Park) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

We conducted parametric performance tests for hybrid solar still, which can be operated by solar thermal energy and/or waste heat. In this study, the solar radiation was used as thermal energy of the hybrid solar still with the 2 ㎡ collecting area. Experimental parameters include insulation condition at side glasses of the solar collecting part, reflecting fins in the basin of the solar still, seawater level in the basin of the solar still, and solar insolation. In the result of the performance tests for two identical hybrid solar stills, insulation of the side glasses improved performance. Reflecting fins in the basin had a negative effect on the production of distillates of basin part and multi-effect diffusion part of the solar still. Lower seawater level in the basin and higher solar insolation showed the better performance of the hybrid solar still.

펨토초레이저 백내장수술 후 건성안에 대한 0.15% 무보존제 히알루론산나트륨의 임상적 효과

김태환(Tae Hwan Kim),정병훈(Byunghoon Chung),김강윤(Kang Yoon Kim),전익현(Ikhyun Jun),서경률(Kyoung Yul Seo),김응권(Eung Kweon Kim),김태임(Tae-im Kim) 대한안과학회 2021 대한안과학회지 Vol.62 No.7

목적: 펨토초레이저 백내장수술 후 발생하는 건성안에 대한 0.15% 무보존제 히알루론산나트륨 점안액의 임상적 효과를 분석하고자 하였다. 대상과 방법: 본원에서 진료 중인 건성안 환자들 중 펨토초레이저 백내장수술을 시행한 총 37안을 대상으로 수술 후 0.15% 무보존제히알루론산나트륨 점안액을 사용한 치료군 19안, 사용하지 않은 대조군 18안에 대해 수술 전, 후 1, 3개월째 각결막형광염색점수, 눈물막파괴시간, 1형 쉬르머검사, 안구표면질환지수, 눈꺼풀 마이봄샘 평가, 눈물 지질층 두께를 측정하였다. 결과: 치료군에서는 수술 후 3개월째 안구표면질환지수의 유의한 감소, 눈물막파괴시간의 증가, 각결막형광염색점수의 감소, 1형 쉬르머검사의 유의한 증가가 확인된 반면, 대조군에서는 수술 후 1, 3개월째 유의한 쉬르머검사의 감소, 1개월째 마이봄샘 성상 악화, 3개월째 눈물막파괴시간 감소가 관찰되었다. 안구표면질환지수는 수술 후 1, 3개월째 치료군에서 유의하게 낮았으며, 눈물막파괴시간은 수술 후 3개월째 치료군에서 유의하게 높게 나타났다. 또한 수술 후 3개월째 치료군에서 마이봄샘 성상이 유의하게 좋은 결과를 보였다. 이외에 각결막형광염색점수와 눈물 지질층 두께를 포함한 다른 건성안 지표에 대해서는 치료군과 대조군 간 유의한 차이를 보이지 않았다. 결론: 펨토초레이저 백내장수술 후 무보존제 0.15% 히알루론산나트륨 점안액 사용은 수술 후 발생하는 건성안 증상을 경감시키고 눈물막 안정성 향상에 도움을 줄 수 있다. Purpose: The efficacy of using preservative-free 0.15% sodium hyaluronate eyedrops for dry eye disease after femtosecond laser- assisted cataract surgery (FLACS) was evaluated. Methods: This prospective randomized study was conducted on patients with dry eye who were scheduled for FLACS among those with Tear Film & Ocular Surface Society Dry Eye Workshop II Dry Eye Levels 1 and 2. In total, 37 eyes scheduled for FLACS were randomized to the treatment group (n = 19) or control group (n = 18). Corneal and conjunctival fluorescein staining (CFS), tear breakup time (TBUT), Schirmer I test (SIT) value, ocular surface disease index (OSDI), meibomian gland evaluation result, and lipid layer thickness were evaluated for all patients, preoperatively and at 1 and 3 months postoperatively. Results: In the treatment group, the OSDI and CFS scores were significantly lower at 3 months postoperatively than at baseline, but the TBUT and SIT values were significantly increased. In the control group, TBUT was significantly shorter at 3 months postoperatively than at baseline, SIT values were significantly decreased at 1 and 3 months postoperatively compared with the baseline, and meibum quality was significantly aggravated at 1 month postoperatively compared with the baseline. In the treatment group, OSDI improved significantly from baseline at 1 and 3 months. TBUT increased significantly in the treatment group at postoperative 3 months. Meibomian gland quality showed clinically better results in the treatment group than in the control group at postoperative 3 months. There were no significant differences in corneal and CFS, lipid layer thickness, and other dry eye disease parameters between the treatment and control groups. Conclusions: Preservative-free 0.15% sodium hyaluronate eyedrops were effective for improving dry eye symptoms and tear film stability after FLACS.