위성통신에서 강우 감쇠 보상을 위한 UEP 방식의 계층적 부호화 방식

정지원,Jung Ji-Won 한국전자파학회 2006 한국전자파학회논문지 Vol.17 No.9

본 논문에서는 Ka 대역 초고속 위성 방송 시스템에서 강우 감쇠에 대처하면서 가입자에게 지속적으로 방송을 제공하기 위해 unequal error protection(UEP) 방식을 이용한 계층적 부호화 방식에 대한 연구를 하였다. 신호의 중요도에 따라 변조 방식 및 채널 코딩 방식을 달리하는 time sharing 방식과 달리 하나의 변조 방식을 이용하여 성상도 위치에서 신호의 중요도에 따라 신호간의 최소 거리를 다르게 배치하는 UEP 방식에 대한 구조 및 성능을 분석하였으며, 성능 분석을 토대로 최적의 방식을 제시하였다. In this paper, we studied hierarchical channel coding scheme using unequal error protection method fur consecutively broadcastingservice under the rain attenuation of Ka band satellite broadcasting. Unlike time-sharing methods, which are design for different channel coding scheme in according to different modulation, unequal error protection method is made in such way that minimum distance between signals are different for importance of signals with same modulation. Consequently we proposed optimal method according to performance analysis.

이중분무의 중첩영역과 단일분무에서 액적의 거동 특성

정지원,차건종,김덕줄,Jung, Ji-Won,Cha, Keun-Jong,Kim, Duck-Jool 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.10

The objectives of this study was to investigate the spray characteristics of single spray and twin spray in the overlap region such as mean axial velocity, mean radial velocity, mean droplet size and probability density function of droplet size. A phase doppler anemometer was used as the measurement system for droplet size and velocity. In case of single spray, injection pressure was varied from 0.2MPa to 0.7MPa. Mean axial velocity, mean radial velocity and droplet size were decreased as the distance below nozzle tip was increased. In case of twin spray, the spray characteristics were measured by varying the distance between two nozzles from 127mm to 155mm. In the overlap region, the boundary of the overlap region was determined by obtaining the distribution of mean axial and radial velocity. Droplet size was increased as the distance from nozzle tip was increased. It was found that the distribution of droplet size for twin spray in the overlap region was different to single spray.

한국인 나이관련황반변성 환자의 우울 및 불안에 대한 조사 및 그 영향에 대한 고찰

정지원,문연성,Ji Won Jung,Yeon Sung Moon 대한안과학회 2012 대한안과학회지 Vol.53 No.6

Purpose: To examine the degree of depression and anxiety in Korean patients with age-related macular degeneration (AMD) and to evaluate the influence of mood disturbance on patient’s treatment satisfaction and compliance. Methods: Forty-four patients with AMD and thirty-three controls comprised the study populations. Patients and controls rated themselves on the Korean Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI). The effect of mood disturbance on the patient’s satisfaction and compliance was evaluated. Results: The depression and anxiety scores were significantly higher in patients with AMD. The mood disturbance was negatively correlated with the patient’s satisfaction and compliance. 14 patients (31.8%) were lost to follow-up 1 year later. The depression and anxiety scores of these patients were higher than those of remaining thirty patients. Conclusions: Depression and anxiety of patients with AMD affect on patient’s satisfaction and compliance. So recognition and management of mood disturbance may help improving visual function and maintaining quality of life in patients. J Korean Ophthalmol Soc 2012;53(6):792-800

DVB-S2 기반 LDPC 복호기의 멀티레벨 변조 방식 적용을 위한 디맵핑 알고리즘

정지원,정진희,김민혁,Jung Ji-Won,Jeong Jin-Hee,Kim Min-Hyuk 한국전자파학회 2006 한국전자파학회논문지 Vol.17 No.7

DVB-S2 표준안에서는 다양한 부호화율과 그에 따른 다양한 변조 방식을 지원한다. 따라서 본 논문에서는 LDPC에 8 PSK 이상의 다치 변조 방식 적용을 위해 수신단에서 비트 분리 방법을 제시한다. 수신된 I, Q 심볼만을 이용하여 세 비트 이상의 비트를 분리하기 위한 LLR 방식에 기초를 하여 LLR 방식의 단점인 복잡도를 개선하기 위해 Euclidean, MAX, Sector 방식을 제시하였다. DVB-S2 offers various coding rate and modulation schemes. Therefore this paper proposes bit split methods to applying to multilevel modulation. Log-likelihood ratio method splits multilevel symbols to soft decision symbols using the received in-phase and quadrature component based on Gaussian approximation. However it is too complicate to calculate and to implement hardware due to exponential and logarithm calculation. Therefore this paper presents Euclidean, MAX and Sector method to reduce the high complexity of LLR method.

교사 학생 심층신경망을 활용한 다채널 원거리 화자 인증

정지원,허희수,심혜진,유하진,Jung, Jee-weon,Heo, Hee-Soo,Shim, Hye-jin,Yu, Ha-Jin 한국음향학회 2018 韓國音響學會誌 Vol.37 No.6

원거리 발성은 화자 인증 시스템의 성능을 하락시키는 주요 요인으로 알려져 있다. 본 논문에서는 교사 학생 학습을 이용하여 원거리 발성에 의한 화자 인증 시스템의 성능 하락을 보상하는 기법을 제안한다. 교사 학생 학습은 미리 학습된 교사 심층신경망의 출력과 학생 신경망의 출력이 같아지도록 학생 신경망을 학습하는 기법이다. 여기서 교사 신경망에는 근거리 발성을, 학생 신경망에는 원거리 발성을 입력한 뒤, 두 신경망의 출력을 동일하게 만드는 과정을 통해 원거리 발성을 보상할 수 있을 것이라고 기대하였다. 하지만 원거리 발성을 보상하는 과정에서, 근거리 발성에 대한 인식률이 저하되는 현상을 실험적으로 발견하였다. 위와 같은 현상을 예방하기 위해 본 논문에서는 교사 심층신경망을 학생 심층신경망의 초깃값으로 사용하는 기법과 학생 심층신경망을 근거리 발성에 대해서도 학습하는 기법을 제안하였다. 모든 실험은 원 음성을 입력 받는 심층신경망을 활용해 수행하였다. 동일한 발성을 각각 4 채널로 근거리와 원거리에서 자체적으로 수집한 문장 종속 데이터셋을 활용하였다. 동일 오류율을 기준으로 근거리 / 원거리 발성에 대한 화자 인증 성능을 평가한 결과 교사 학생 학습을 사용하지 않을 경우 2.55 % / 2.8 %, 기존의 교사 학생 학습을 사용할 경우 9.75 % / 1.8 %, 제안한 기법들을 적용한 경우 2.5 % / 2.7 %의 오류율을 확인하였다. Far field input utterance is one of the major causes of performance degradation of speaker verification systems. In this study, we used teacher student learning framework to compensate for the performance degradation caused by far field utterances. Teacher student learning refers to training the student deep neural network in possible performance degradation condition using the teacher deep neural network trained without such condition. In this study, we use the teacher network trained with near distance utterances to train the student network with far distance utterances. However, through experiments, it was found that performance of near distance utterances were deteriorated. To avoid such phenomenon, we proposed techniques that use trained teacher network as initialization of student network and training the student network using both near and far field utterances. Experiments were conducted using deep neural networks that input raw waveforms of 4-channel utterances recorded in both near and far distance. Results show the equal error rate of near and far-field utterances respectively, 2.55 % / 2.8 % without teacher student learning, 9.75 % / 1.8 % for conventional teacher student learning, and 2.5 % / 2.7 % with proposed techniques.

DVB-S2 시스템을 위한 저복잡도 LDPC 복호 알고리즘

정지원,Jung Ji-Won 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.10

본 연구에서는 DTV, HDTV 서비스를 동시에 제공하는 차세대 위성 방송시스템의 표준안인 DVB-S2에서 채널 부호화 알고리즘으로 채택한 LDPC 부호의 복호 알고리즘에 대해 연구를 하였다. 샤논의 한계에 근접하기 위해서는 큰 블록 사이즈의 LDPC 부호어 길이와 많은 반복 횟수를 요구한다. 이는 많은 계산량을 요구하며, 그리고 이에 따른 전력 소비량(power consumption)을 야기시키므로 본 논문에서는 세 가지 형태의 low complexity LDPC 복호 알고리즘을 제시한다. 첫째로 큰 블록 사이즈와 많은 반복 회수는 많은 계산량과 power 소모량을 요구하므로 성능 손실 없이 반복 횟수를 줄일 수 있는 SUBSET 방법을 이용한 복호 알고리즘, 둘째로 early stop 알고리즘에 대해 연구하였고, 셋째로 비트 노드 계산과 체크 노드 계산시 일정한 신뢰도 값보다 크면 다음 반복시 계산을 하지 않는 early detection 알고리즘에 대해 연구하였다. In this paper, we first review LDPC codes in general and a belief propagation algorithm that works in logarithm domain. LDPC codes, which is chosen for second generation digital video broadcasting standard, are required a large number of computation due to large size of coded block and iteration. Therefore, we presented two kinds of low computational algorithm for LDPC codes. First, sequential decoding with partial group is proposed. It has same H/W complexity, and fewer number of iteration's are required at same performance in comparison with conventional decoder algerian. Secondly, early detection method for reducing the computational complexity is proposed. Using a confidence criterion, some bit nodes and check node edges are detected early on during decoding. Through the simulation, we knew that the iteration number are reduced by half using subset algorithm and computational complexity of early detected method is about $50\%$ offs in case of check node update, $99\%$ offs in case of check node update compared to conventional scheme.

FTN 전송기법에서 최적의 필터 roll-off 값 및 탭수 설정

정지원,Jung, Ji-Won 한국정보전자통신기술학회 2015 한국정보전자통신기술학회논문지 Vol.8 No.2

본 논문은 인접 심볼 간의 간섭이 발생하지 않는 최대 데이터 전송률인 Nyquist rate 보다 빠르게 데이터를 전송하여 전송량을 증가시키는 FTN(Faster than Nyquist) 기법을 이용하여 최적의 필터 roll-off 값과 탭 수를 설정한다. FTN 신호 전송 시 발생하는 ISI(Inter-Symbol Interference)를 최소화하기 위해 LDPC부호를 기반으로 하는 터보 등화 모델을 적용하였으며, FTN 신호의 필터 roll-off 값과 탭 수에 따라 시뮬레이션하여 성능을 향상시키고 최적의 값을 설정하였다. In this paper, to increase the throughput for wireless communication, FTN methods that is faster than Nyquist rate are used recently. To improve performance, turbo equalization algorithms that iteratively exchange probabilistic information between soft Viterbi equalizer and LDPC decoder to minimize ISI are applied in this paper. In FTN transmission, the performance depends on roll-off value and number of tabs of SRRC(Square Root Raised Cosine) filter. Therefore, Based on simulation, this paper present optimal number of filter coefficient and tab for various ISI factor of ${\tau}$.

Effect of stellate ganglion block on laryngopharyngeal reflux disease

정지원,Hye Jung Chun,이미순,Ki Ryang Ahn,Chun Sook Kim,Kyu Sik Kang,유시현,정진헌,김난설,서용한,Hyung Youn Gong,Yong Man Lee 대한마취통증의학회 2013 Korean Journal of Anesthesiology Vol.64 No.5

Background: Laryngopharyngeal reflux (LPR) disease has many symptoms such as globus pharyngeus, excessive throat clearing and hoarseness. The aim of this study was to investigate the effect of stellate ganglion block (SGB) in addition to proton pump inhibitors (PPI) on LPR. Methods: Fifty patients complaining of more than 3 typical LPR symptoms for over 3 months were enrolled in the study. The P group took PPI for 8 weeks. The SP group took PPI and interwent a series of 8 SGB procedure once a week during the period of treatment. The blocks were performed one at a time unilaterally on the right and left stellate ganglions by injecting 1% mepivacaine 6 ml. We evaluated the reflux symptom index (RSI) before treatment and following 4 weeks and 8 weeks of treatment in both groups. Results: After 4 weeks of treatment, the RSI of the P group decreased, but not significantly, to 16.6 ± 6.8 compared with the baseline value of 19.2 ± 2.7 (P = 0.093), whereas the RSI of the SP group decreased significantly to 9.8 ± 3.3 compared with the baseline value of 19.0 ± 4.7 (P = 0.000). After 8 weeks of treatment, the RSI of the P group decreased significantly to 13.7 ± 6.7 (P= 0.001) and the RSI of the SP group also decreased significantly to 7.7 ± 3.4 (P= 0.000). There were significant differences in the RSI between the two groups after 4 weeks (P = 0.000) and 8 weeks (P = 0.001) of treatment. Conclusions: The symptoms of LPR improved earlier when PPI therapy was combined with SGB compared with PPI therapy alone.

백내장 수술 후 서로 다른 임상 양상을 보인 스테노트로포모나스 말토필리아 안내염 2예

정지원,강행구,진희승.Ji Won Jung. MD. Haeng Ku Kang. MD. Hee Seung Chin. MD. PhD 대한안과학회 2012 대한안과학회지 Vol.53 No.1

Purpose: To report 2 different cases of postoperative endophthalmitis caused by Stenotrophomonas maltophilia after cataract surgery. Case summary: A 73-year-old male with diabetes mellitus developed severe pain in the right eye 2 weeks after cataract surgery. The patient was hospitalized with a diagnosis of infectious endophthalmitis, and vitrectomy was performed. Cultures of aqueous humor and vitreous aspirate revealed S. maltophilia. On day 30 after vitrectomy, his visual acuity had improved to 20/20 and there were no recurrences. A 61-year-old female with no significant past medical history was referred for uveitis or delayed onset endophthalmitis 30 days after cataract surgery. An anterior chamber tapping and cultures were performed. S. maltophilia and Aspergillus fumigatus were isolated. The patient received antibiotics and antifungal agents and her visual acuity improved to 20/25. Conclusions: S. maltophilia has been considered a life-threatening systemic opportunistic infection; however, the organism has recently been reported as an exogenous pathogen of endophthalmitis following cataract surgery. Herein, 2 different cases of S. maltophilia endophthalmitis after cataract surgery are presented and compared with previous case reports. J Korean Ophthalmol Soc 2012;53(1):161-167

소아기에 발현한 C형 Niemann Pick 병 1례

정지원,서고훈,오아름,진희경,배재성,김구환,유한욱,이범희,Jung, Jiwon,Seo, Go Hun,Oh, Arum,Jin, Hee Kyung,Bae, Jae-Sung,Kim, Gu-Hwan,Yoo, Han-Wook,Lee, Beom Hee 대한유전성대사질환학회 2018 대한유전성대사질환학회지 Vol.18 No.1

C형 Niemann-Pick 병은 NPC1 및 NPC2 유전자의 돌연변이로 인해 발생하며 상염색체 열성으로 유전된다. 신생아 간염 및 간비비대로 발현하며 안구의 수직운동 마비, 조화운동불능, 근육긴장이상, 경련 등의 신경학적 증상이 서서히 발현 하는 것을 특징으로 한다. 저자들은 복부 팽만 및 심한 비장비대로 입원한 3세 남아에서 간 조직 검사 및 유전자 검사, 섬유모세포의 Filipin 염색으로 확진 된 C형 Niemann-Pick 병 1례를 보고하는 바이다. Niemann Pick type C disease (NPC) is an inherited progressive neurodegenerative disorder, due to defects of intracellular lipid trafficking and storage. Hepatosplenomegaly may prevail, while progressive neurodegenerative symptoms such as cerebellar involvement, dystonia, vertical supranuclear ophthalmoplegia, cataplexy, and eventually seizures starting at juvenile or late infantile period may accompany after normal early development. Here we describe a 3-year-old Korean boy with NPC who presented with splenomegaly at age 3. Liver biopsy showed characteristic foamy cell stained by periodic acid-schiff, and molecular analysis for NPC1 identified the compound heterozygous mutations, novel mutation of c.1631G>A (p.Trp544Ter) and c.2662C>T (p. Pro888Ser) as a known mutation. Filipin was strongly stained with unesterified cellular cholesterol in the patient's skin fibroblasts. The patient has received migulstat since age 3 years and his long-term outcome is needed to be observed.