DQN 기반 TCP 혼잡제어 알고리즘의 성능평가

서상진,조유제 한국통신학회 2024 韓國通信學會論文誌 Vol.49 No.4

기존의 TCP 혼잡제어는 느린 혼잡 윈도우 (cwnd) 증가율로 인해 전송 대역폭이 매우 크거나, 채널의 특성이빈번하게 변화하는 환경에서 사용 가능한 대역폭을 충분히 활용하지 못하는 문제점이 있다. 이러한 문제를 개선하기 위해 기계학습을 적용한 적응형 TCP 혼잡제어에 관한 연구가 꾸준히 진행되고 있다. 본 논문에서는 강화학습의 일종인 Deep Q-Network (DQN)을 TCP 혼잡제어 알고리즘에 적용하여 성능을 개선한 DQN-based NewReno 와 DQN-based CUBIC을 소개하였다. 구현한 알고리즘들은 NS-3 시뮬레이터를 통해 성능 평가를 수행하였으며, 실험 결과를 통해 DQN-based CUBIC이 특히 기존 혼잡제어에 비해 높은 처리량을 보이고, 서로 다른 혼잡제어프로토콜 간의 공평성과 round trip time (RTT) 공평성 모두 향상됨을 확인하였다. The existing TCP congestion control suffers from the problem of slow congestion window (cwnd) increase, leading to underutilization of available bandwidth in environments where there is either a very large link bandwidth or frequent changes in channel characteristics. To address these issues, research on adaptive TCP congestion control using machine learning has been consistently progressing. In this paper, we propose DQN-based NewReno and DQN-based CUBIC, which enhance performance by applying a type of reinforcement learning, Deep-Q Network (DQN) to TCP congestion control algorithms. The implemented algorithms underwent performance evaluation using the Network Simulator 3 (NS3). Experimental results reveal that DQN-based CUBIC, in particular, demonstrates higher throughput compared to traditional congestion control. Additionally, fairness between different congestion control and round-trip time (RTT) fairness is also improved.

망막혈관폐쇄 질환에서 경동맥초음파로 측정된 내중막두께

서상진,장현덕,이수정,박정민,Sang Jin Seo,Hyun Duk Jang,Soo Jung Lee,Jung Min Park 대한안과학회 2014 대한안과학회지 Vol.55 No.4

Purpose: To evaluate the findings of carotid ultrasonography performed on patients with retinal vascular disease and to determine the risk of cardiovascular disease and association of retinal vascular disease and cardiovascular disease. Methods: From December 2009 to May 2012, patients diagnosed with central retinal artery occlusion (CRAO, n = 18), central retinal vein occlusion (CRVO, n = 23), and branch retinal vein occlusion (BRVO, n = 68) underwent carotid ultrasonography. We evaluated the intima-media thickness (IMT) of the common carotid artery (CCA) and the internal carotid artery (ICA), stenosis and the number of plaques, and then compared these results with those of a healthy control group (n = 221). Results: The mean CCA-IMT and ICA-IMT were significantly higher in the CRAO and BRVO groups compared with the control group. On the contralateral side, CCA-IMT was increased in the CRAO, BRVO, and CRVO groups and ICA-IMT was increased in the CRAO and BRVO groups compared with the control group. Contralateral CCA stenosis was higher in the CRVO group (9.1%) and ipsilateral ICA stenosis in CRAO group (21.7%) was significantly higher than that of the control group. Plaque was observed better in all groups compared with the control group. The proportion of patients risk for cardiovascular disease, i.e. those who had IMT thickenesses more than 1.0 mm, was higher in the CRAO and BRVO groups compared with the control group. Conclusions: The carotid ultrasound findings of patients with retinal vascular diseases showed increased IMT and plaque. The group of patient at risk for cardiovascular disease, which was defined with carotid artery IMT, was higher in patients with retinal vascular disease. Therefore, in patients with retinal vascular disease, carotid artery ultrasonography and the overall management and treatment of cardiovascular disease are necessary. J Korean Ophthalmol Soc 2014;55(4):541-547

황반전막환자에서 빛간섭단층촬영 형태에 따른 수술결과

서상진,이수정,박정민,Sang Jin Seo,Soo Jung Lee,Jung Min Park 대한안과학회 2013 대한안과학회지 Vol.54 No.5

Purpose: To determine the influence of morphologic classification based on optical coherence tomography (OCT) on epiretinal membrane (ERM) surgery outcomes. Methods: We retrospectively reviewed the medical records of 77 eyes with ERM treated by vitrectomy with ERM peeling. By using OCT, the preoperative ERM was classified into four types: diffuse (DIF), cystoids macular edema (CME), pseudolamellar hole (PLH), and vitreomacular traction (VMT). The postoperative changes of central macular thickness (CMT) and best-corrected visual acuity (BCVA) were compared. Results: Approximately six months postoperatively, the DIF type had the best BCVA for both idiopathic and secondary ERM, followed by the PLH, CME, and VMT types. On the other hand, regarding the mean BCVA improvement, the VMT type was the best, followed by the DIF, PLH, and CME types. When comparing the difference in BCVA improvement by each type, idiopathic ERM showed a clearer distinction when the inner segment/outer segment (IS/OS) junction was not disrupted. Conclusions: BCVA improvement was significantly different depending on the morphologic classification of ERM by using OCT. Especially in cases of ERM with an intact IS/OS junction, the morphologic classification can help predict surgical outcomes. J Korean Ophthalmol

하부열공망막박리에서 실리콘기름 충전술의 수술결과 및 의의

서상진,이수정,박정민,Sang Jin Seo,Soo Jung Lee,Jung Min Park 대한안과학회 2012 대한안과학회지 Vol.53 No.9

Purpose: To compare the surgical outcomes of 23-gauge transconjunctival sutureless vitrectomy (TSV) with silicone oil tamponade versus 20-gauge PPV with sclera buckling (SB) and SF6 gas tamponade for the repair of rhegmatogenous retinal detachment (RRD) with inferior breaks. In addition, silicone oil tamponade was evaluated as an alternative option for patients with inferior RRD. Methods: Two different types of surgery were performed on two groups of patients with inferior RRD: 23-gauge TSV with silicone oil tamponade (group 1) and 20-gauge PPV with SB and SF6 gas tamponade (group 2). The preoperative clinical features, anatomical success rate, complications, functional outcomes (visual acuity, VA, intraocular pressure, IOP), and surgical time were retrospectively evaluated. Results: The primary surgical success rates were 94% and 78% in groups 1 and 2, respectively. The final success rate was 100% in both groups. Therefore, in terms of success rate, there was no difference between the two groups. No statistically significant difference in IOP change or complication rate was observed between the two groups. VA change was significantly better and surgical time was shorter in group 1. Conclusions: No statistically significant difference of anatomical success rate or complication rate between 23-gauge TSV with silicone oil tamponade and 20-gauge PPV with SB and SF6 gas tamponade was found for inferior RRD. However, surgical time was shorter in group 1. A 23-gauge TSV with silicone oil tamponade could be an alternative to 20-gauge PPV with SB and SF6 gas tamponade for patients with inferior RRD, especially patients who cannot maintain a prone posture. J Korean Ophthalmol Soc 2012;53(9):1296-1303

선천성 특발성 작은 동공 1예

서상진,김대윤,Sang Jin Seo,Dae Yune Kim 대한안과학회 2012 대한안과학회지 Vol.53 No.3

Purpose: To report a case of congenital idiopathic microcoria corrected with pupilloplasty and amblyopia treatment. Case summary: A 4-year-old girl was referred for pupillary abnormality of the left eye. Her mother experienced no problems during gestation, and the patient was born at full term. On initial examination, visual acuity was 20/25 in the right eye and counting finger at 50 cm in the left eye. Slit lamp examination revealed that the left pupil was displaced superonasally. A band of fibrous tissue extended across the left pupil and there was no red reflex. There was very slight reaction to mydriatics. Using 23-gauge vitrectomy scissors, a pupilloplasty was performed, and the synechiae are removed. Postoperatively, the pupillary light reflex was brisk, and occlusion therapy was initiated. After 3 months, the visual acuity of the left eye improved to 20/30. Conclusions: In our case, although microcoria was diagnosed at a relatively old age, the patient’s clinical features were consistent with congenital idiopathic microcoria. Therefore, we diagnosed the patient with gradually progressed congenital idiopathic microcoria. In the case of typical congenital idiopathic microcoria, the red-reflex is absent at birth because of the small pupil. However, as in our case, it is possible that the pupil can contract gradually due to movement of the fibrous strand. The point must be considered in such patients. J Korean Ophthalmol Soc 2012;53(3):478-481

Size Control of Nanocrystals in InGaZnO₄ Thin Films Fabricated by Using the Sol-gel Method

서상진,조진형,장윤형,김철환 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.2

We report the structural properties of InGaZnO4 (IGZO) thin films prepared by using the sol-gel method. The structural properties of IGZO thin films were controlled by using the film thickness and thermal annealing temperature. In this study, the crystallization temperature of amorphous IGZO thin films was observed to be about 700 C. Also, we observed that the crystal size of IGZO thin films increased as the thickness and the annealing temperature were increased. In addition, we could observe that the atomic ratio of In, Ga and Zn of the IGZO thin film was slightly different from the molar ratio of a previous IGZO sol-gel solution (In:Ga:Zn = 1:1:1) post-annealed at 900 C because In and Zn are more volatile than Ga. The study of the crystallization of amorphous IGZO thin films provides an understanding of the growth mechanisms and thermal annealing effects for IGZO nanocrystals.

터널의 시각순응시설

서상진 한국조명전기설비학회 2004 조명.전기설비 Vol.18 No.5

PLD법으로 제작한 비정질 IGZO 박막 트랜지스터의 UV광 조사 연구

서상진,조진형,김철환,장윤형 한국물리학회 2014 새물리 Vol.64 No.8

We have investigated the transport properties of amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) fabricated by using the pulsed laser deposition (PLD) method. The threshold voltage (V_t) was shifted to a positive bias by both an increase in the oxygen partial pressure during the deposition and an increase in the during post heat treatment. This shift was due to decreases of the numbers of interface defects and free electron carriers caused by the reduction in the number of oxygen vacancies. In the KPFM (Kelvin probe force microscopy) measurements, the histogram data showed that the surface potential decreased with time due to a reduction in the number of oxygen vacancies because the measurements were performed in air. UV illumination resulted in a negative shift of the V_t in the absence of any bias stress. A persistent negative shift of the V_t was observed after removal of the UV illumination due to the photo-induced hole trap state in the interface, and sufficient time was needed to recover to the initial V_t. 펄스 레이저 증착 (pulsed laser deposition, PLD)법을 이용하여 비정질 InGaZnO (amorphous InGaZnO, a-IGZO) 박막트랜지스터 (thin film transistor, TFT)를 제작하고 그 전달 특성 (transfer characteristics)을 조사하였다. 증착 시 산소 분압 (50, 80 and 100 mTorr)의 증가 및 후 열처리 (300℃ , 1 hour)에 의해 문턱 전압 (threshold voltage, V_t)은 양의 방향으로 이동하였다. 이와 같은 문턱전압 이동은 산소 공공 (oxygen vacancy)의 감소에 의한 캐리어의 감소뿐 아니라 채널층과 게이트절연층 사이에 존재하는 계면결함의 감소 때문으로 보인다. KPFM (Kelvin probe force microscopy)을 이용한 a-IGZO 박막의 표면전위 측정 실험에서는 대기 노출에 의해서 표면전위분포가 시간이 지남에 따라 감소하는 것으로 나타났다. 또한 UV 광 조사에 의해 V_t는 음의 방향으로 이동하였다. UV 광 제거 후에도 a-IGZO와 SiO$_2$ 계면의 강한 홀 트랩 때문에 초기 값으로 회복 (recovery)하기 위해서는 충분한 시간이 필요한 것으로 나타났다.

비만도에 따른 최대지방연소를 위한 운동강도 설정에 관한 연구

서상진,박수연,박철빈 경희대학교 체육과학연구소 1999 體育學論文集 Vol.27 No.-

In order to provide the basic data required for an effective physical exercise program to get rid of obesity, women in their 20s to 50s who had never participated in a regular physical exercise were classified into GroupI, GroupII, and GroupIII consisting of 10 persons each with 25 to 30%,34 to 35%, and over 36% of body fat rate respectively, and then they were checked up with their maximum physical exercise intensity by using RAMP II protocol to analyze relations of physiological causes of change at the time of the maximum fat oxidation intensity for the three groups with the result of analysis as follows, 1.Maximum fat oxidation and fat -free weight(r=.396, p〈.03), oxygen uptake(r=.569, p〈.001) and ruts piratory exchange rate(r=.673, p〈.000) have notable co-relations one another. 2.At the time of the maximum fat oxidation intensity, oxygen uptake, heart rate, respiratory exchange rate, fat oxidation, and energy consumption among the 3 group have shown no notable statistical difference one another. 3.At the time of the maximum fat oxidation intensity, percentage in the maximum oxygen uptake value(% VO2max) shows a notable difference among the three groups. A post verification shows GroupIII has a notable difference from GroupI or GroupII(p〈.05) while there is no notable difference between GroupII and GroupI. In conclusion at the time of the maximum fat oxidation intensity, GroupIII(body fat rate of over 36%) shows a notably high relative intensity. Accordingly people of high body fat rate need the tensity of 60% VO2max in aerobic exercise to reduce their fat.

창원시 창진지구 지하수자원 관리지역 분석

서상진,추연우,백미경,이병선,이규상 대한지질공학회 2021 대한지질공학회 학술발표회논문집 Vol.2021 No.1