Sound Quality Enhancement by using the Single Core Exciter in OLED Panel

( Sungtae Lee ),( Kwanho Park ),( Hyungwoo Park ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.2

With the development of display engineering and technology, the screen and sound quality of information devices such as TVs are improving. The screen used LEDs via LCD and PDP and a large flat panel in the early CRT to create super-high resolution. The sound is improved by directly vibrating a thin and simple panel, such as an OLED. In our previous study, the exciter speaker was attached to the rear of the OLED panel to be used as the diaphragm of the speaker, and the sound quality was as good as that of the TV using the existing dynamic speaker. This method supplied the viewer with the direct sound coming from the panel, delivering clear sound, and the sound and image came from the same location, thus giving the viewer high immersion and maximizing the effect of information transfer. OLED exciter speakers, however, have a special directivity, which tends to slightly attenuate the tone at the very center of the screen. This study improves the sound quality by improving the structure of the exciter speaker and the radiated sound of the flat panel display. A 2-in-1 Exciter is made into a single core to improve the speaker's radiation pattern.

Evaluation Model of Defense Information Systems Use

Sungtae Kim,Hanjun Lee,Hyukjin Kwon,Sangho Lee 한국정보기술융합학회 2015 JoC Vol.6 No.1

The Republic of Korea’s Ministry of National Defense (ROK-MND) has developed various defense information systems, and most of the projects for the development of such information systems are now in their completion or maintenance stage. Because information system (IS) use is a precondition to get the benefit and it can show what IS should be improved, measuring IS use is important. In this study, we benchmarked ISO/IEC 25010 and a guideline of Korean government for operational performance of information systems. We proposed the framework that can measure the degree of IS use with three perspectives such as task support, relevant information provision, and user convenience from the viewpoint of users, and conducted an evaluation of defense information systems with it. Moreover, we classified the defense information systems into four groups by two dimensions such as the status of use and the frequency of maintenance demand, and then made suggestions for better management of IS in each classification.

Efficacy of salivary versus subgingival bacterial sampling for the detection and quantification of periodontal pathogens

Lee, Yoonsub,Hong, Yoojin,Kim, Bome,Lee, Dajung,Kim, Sungtae,Rhyu, In-chul Korean Academy of Periodontology 2020 Journal of Periodontal & Implant Science Vol.50 No.6

Purpose: The aim of this study was to investigate the efficacy and validity of subgingival bacterial sampling using a retraction cord, and to evaluate how well this sampling method reflected changes in periodontal conditions after periodontal therapy. Methods: Based on clinical examinations, 87 subjects were divided into a healthy group (n=40) and a periodontitis group (n=47). Clinical measurements were obtained from all subjects including periodontal probing depth (PD), bleeding on probing (BOP), clinical attachment loss (CAL), and the plaque index. Saliva and gingival crevicular fluid (GCF) as a subgingival bacterial sample were sampled before and 3 months after periodontal therapy. The salivary and subgingival bacterial samples were analyzed by reverse-transcription polymerase chain reaction to quantify the following 11 periodontal pathogens: Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythus (Tf), Treponema denticola (Td), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn), Pavimonas micra (Pm), Campylobacter rectus (Cr), Prevotella nigrescens (Pn), Eikenella corrodens (Ec), and Eubacterium nodatum (En). Results: Non-surgical periodontal therapy resulted in significant decreases in PD (P<0.01), CAL (P<0.01), and BOP (P<0.05) after 3 months. Four species (Pg, Tf, Pi, and Pm) were significantly more abundant in both types of samples in the periodontitis group than in the healthy group. After periodontal therapy, Cr was the only bacterium that showed a statistically significant decrease in saliva, whereas statistically significant decreases in Cr, Pg, and Pn were found in GCF. Conclusions: Salivary and subgingival bacterial sampling with a gingival retraction cord were found to be equivalent in terms of their accuracy for differentiating periodontitis, but GCF reflected changes in bacterial abundance after periodontal therapy more sensitively than saliva.

Efficacy of sonic-powered toothbrushes for plaque removal in patients with peri-implant mucositis

Lee, Jungwon,Lim, Jong Heun,Lee, Jungeun,Kim, Sungtae,Koo, Ki-Tae,Seol, Yang-Jo,Ku, Young,Lee, Yong-Moo,Rhyu, In-Chul Korean Academy of Periodontology 2015 Journal of Periodontal & Implant Science Vol.45 No.2

Purpose: The aim of this study was to evaluate the effectiveness of powered toothbrushes for plaque control in patients with peri-implant mucositis, in comparison with manual toothbrushes. Methods: This randomized, prospective, controlled, clinical parallel study compared the efficacy of manual and powered toothbrushes for plaque control in implant restorations. Patients with bleeding on probing, no residual pocket depth (as indicated by a pocket probing depth ${\geq}5mm$), and no radiological peri-implant bone loss were eligible for this study. Patients were requested to complete a questionnaire describing their oral hygiene habits. The duration and frequency of tooth brushing were recorded by subjects in order to assess their compliance. Clinical parameters, including the modified plaque index (mPI), the modified sulcus bleeding index (mSBI), and clinical photographs (buccal and lingual views) were recorded at baseline and at one-month and two-month follow-up visits. Results: Statistically significant differences between patients who used manual toothbrushes and those who used powered toothbrushes were found regarding the frequency of tooth brushing per day and the duration of brushing at one-month and two-month follow-up visits, while no statistically significant differences were found relating to other oral hygiene habits. A statistically significant difference in patient compliance for tooth brushing was found at one month, while no difference was found at two months. Statistically significant decreases in the mPI and the mSBI were observed in both groups from baseline to the one- and two-month follow-ups. The overall reduction of these parameters was not significantly different between the two groups, except for mPI reduction between baseline and one month of follow-up. Conclusions: Sonic-powered toothbrushes may be a useful device for plaque control in patients with peri-implant mucositis.

Modified tunneling technique for root coverage of anterior mandible using minimal soft tissue harvesting and volume-stable collagen matrix: a retrospective study

Lee, Yoonsub,Lee, Dajung,Kim, Sungtae,Ku, Young,Rhyu, In-Chul Korean Academy of Periodontology 2021 Journal of Periodontal & Implant Science Vol.51 No.-

Purpose: In this study, we aimed to evaluate the clinical validity of the modified tunneling technique using minimal soft tissue harvesting and volume-stable collagen matrix in the anterior mandible. Methods: In total, 27 anterior mandibular teeth and palatal donor sites in 17 patients with ≥1 mm of gingival recession (GR) were analyzed before and after root coverage. For the recipient sites, vertical vestibular incisions were made in the interdental area and a subperiosteal tunnel was created with an elevator. After both sides of the marginal gingiva were tied to one another, a prepared connective tissue graft and volume-stable collagen matrix were inserted through the vestibular vertical incision and were fixed with resorbable suture material. The root coverage results of the recipient site were measured at baseline (T₀), 3 weeks (T₃), 12 weeks (T₁₂), and the latest visit (T_l). For palatal donor sites, a free gingival graft from a pre-decided area avoiding the main trunk of the greater palatine artery was harvested using a prefabricated surgical template at a depth of 2 mm after de-epithelization using a rotating bur. In each patient, the clinical and volumetric changes at the donor sites between T₀ and T₃ were measured. Results: During an average follow-up of 14.5 months, teeth with denuded root lengths of 1-3 mm (n=12), 3-6 mm (n=11), and >6 mm (n=2) achieved root coverage of 97.01%±7.65%, 86.70%±5.66%, and 82.53%±1.39%, respectively. Miller classification I (n=12), II (n=10), and III (n=3) teeth showed mean coverage rates of 97.01%±7.65%, 86.91%±5.90%, and 83.19%±1.62%, respectively. At the donor sites, an average defect depth of 1.41 mm (70.5%) recovered in 3 weeks, and the wounds were epithelized completely in all cases. Conclusions: The modified tunneling technique in this study is a promising treatment modality for overcoming GR in the anterior mandible.

Delayed bone healing by collagen membrane in early phase of 4 weeks

Lee, Jungtae,Lee, Dajung,Oh, Seo-Eun,Park, Kyeong-Mee,Hu, Kyung-Seok,Kim, Sungtae Elsevier 2018 Oral surgery, oral medicine, oral pathology and or Vol.126 No.6

<P><B>Objective</B></P> <P>Barrier membranes are important in maintaining space in guided bone regeneration process by preventing downgrowth of epithelial or connective tissue. In this study, the effects of resorbable membranes during the early stages of bone regeneration in rats with impaired bone healing capacity were investigated.</P> <P><B>Study Design</B></P> <P>Twenty-eight rats were selected for this study. Half of the animals were selected for radiation therapy before surgical procedure (G3, G4). Animals were assigned into 4 groups (G1–G4). A circular defect was created in the central parietal bone. It was covered with resorbable membrane in G2 and G4. After 4 weeks, the animals were sacrificed.</P> <P><B>Results</B></P> <P>At week 4, the new bone formation was observed around the margin of old bone in G1, G2 and G4 groups. Osteoclast was most abundant in the G1 group (18.3 ± 7.7) and least abundant in the G4 group (7.9 ± 4.7). The mean of osteocalcin levels in blood was the highest in the G2 group and lowest in the G3 group. Only G4 group showed significant difference in Runx2 levels between before-treatment and after- treatment.</P> <P><B>Conclusions</B></P> <P>Bone healing is adversely affected after radiation therapy. In addition, resorbable membranes can delay healing in the early stages of bone regeneration.</P>

LCD 제조시스템에서 생산량, 셋업, 작업타입 균형의 종합적 고려를 위한 A3C 기반의 일정계획 모델

이성태(Sungtae Lee),이태희(Tehie Lee),유우식(Woosik Yoo),김관호(Kwanho Kim) 한국전자거래학회 2024 한국전자거래학회지 Vol.29 No.1

LCD 제조는 다수의 설비로 구성된 복잡한 시스템이며, 각 설비는 고가이며 수명이 짧기 때문에 효율적인 일정계획의 중요성이 크다. 이는 특히 LCD 제조시스템의 병목공정인 Photo 공정에서 심화된다. 또한, Photo 공정 내의 목적함수인 KPI(Key Performance Indicators)를 구성하는 요소간에 상충관계가 존재하여 이를 종합적으로 반영하는 고품질의 일정계획을 얻기 어렵다. 이러한 문제를 해결하기 위해 본 연구에서는 A3C 기반의 분산학습 프레임워크를 제안한다. 제안하는 프레임워크는 각 설비에 Local Agent를 배치하여 설비간의 상호관계를 고려하여 작업을 할당할 수 있도록 설계되었다. 또한 포인터 네트워크를 사용하여 할당할 수 있는 모든 작업을 상태로 입력받아 보다 정확한 상태 관측과 작업 할당을 할 수 있다. 실험 결과, 제안하는 모델은 KPI를 구성하는 개별 요소는 다른 모델 대비 뛰어나지 않았지만, 모든 요소를 고르게 고려한 일정계획을 하여 휴리스틱 및 기존 강화학습 모델보다 더 높은 KPI를 기록하였다. LCD manufacturing is a complex system composed of a number of facilities, and since each facility is expensive and has a short lifespan, efficient scheduling is important. This is intensed in the photo process, which is the bottleneck process of the LCD manufacturing system. In addition, it is difficult to get a high-quality schedule because there is a trade-off between the elements constituting the KPI(Key Performance Indicator), which are the objective functions in the photo process. To solve this problem, this study proposes an A3C-based distributed learning framework. The proposed framework is designed to assign tasks in consideration of the interrelationships between the facilities by placing local agents in each facility. In addition, all tasks that can be assigned using the pointer network can be input as a state, allowing more accurate state observation and task allocation. As a result of the experiment, the proposed model recorded a higher KPI than the heuristic and existing reinforcement learning models by making a schedule that evenly considered all factors, although the individual elements constituting the KPI were not superior to other models.

MCU 평가를 위한 HILS 시스템 개발

진성태(Sungtae Jin),이강윤(Kangyoon Lee),이우택(Wootaik Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11

This paper describes implementation and development of Hardware-in-the-Loop Simulation(HILS) system to easily test software functions of Motor Control Unit(MCU) in hybrid electric vehicle. A current automotive ECU has a number of requirements which are legal enforcement, passenger convenience, driver assistance and dynamic drive aspects. These various requirements make the software functions more difficult to enhance reliability. To overcome this problem, this paper presents a better testing environment for maximizing the software quality using the HILS technique. The proposed HILS system can cover not only simulation environment of plant model in real-time but also a means to automatically test the software functions embedded into MCU. For the validation of simulation environment, the experimental results of the developed HILS system are compared with simulation results of the designed plant model on the PC environment. The proposed HILS system will look forward to improving the reliability of software quality and cost-effectiveness of the products.

임의의 환경에서 쿼드트리를 이용한 자율 운송장치의 경로 계획

이성태(Sungtae Lee),김판구(Panku Kim),이윤배(Yunbae Lee) 한국정보과학회 1999 한국정보과학회 학술발표논문집 Vol.26 No.1B

그동안, 장애물이 있는 복잡한 환경에서 AMR(Autonomous mobile robot)이나 AGV(Autonomous guided vehicle)에 대한 경로 탐사 문제는 많은 연구가 되어 왔다. 그런데, 이들 연구의 대부분은 AGV가 이동하고자 하는 환경이 완전히 알려져 있고 장애물은 고정되어 있는 것으로 가정하였다. 때문에, 임의의 환경에서 대해 부분적으로 알고 있거나, 완전히 미지의 환경에서의 AGV 운항을 위해서는, 이들 경로 계획 기법은 직접적으로 적용이 불가능하거나 확장할 수 없는 문제점을 갖고 있었다. 본 논문에서는 이와 같은 문제점을 개선하기 위해서 AGV의 좌우측과 정면에 초음파 센서를 탑재, 출발 지점에서 목표 지점가지 정적이거나 동적인 장애물의 유무와 관계없이 자율적으로 경로를 계획 할 수 있는 AGV를 제안하였다. 특히, 계층적 제어 구조를 도입하여 모듈 상호간에 간섭을 배체하도록 하였으며, 장애물 탐사를 위한 영역 분할을 위해서 쿼드트리 기법을 사용하였다.

SVM-SMO와 Pan-Tilt 웹카메라를 이용한 실시간 얼굴 추적과 얼굴 인식

이호근(Hogeun Lee),김명훈(Myonghun Kim),이지근(Chigeun Lee),정성태(Sungtae Jung) 한국정보과학회 2004 한국정보과학회 학술발표논문집 Vol.31 No.2Ⅱ

웹카메라로부터 입력된 비디오 영상으로부터 실시간 얼굴 인식은 빠르고 정확한 시스템이 요구된다. 따라서 본 논문에서는 객체 분류 기법인 SVM을 이용하여 실시간 다중 얼굴 인식이 가능한 시스템 구현에 중점을 두었다. 본 논문은 얼굴 skin/non-skin 정보를 이용한 얼굴 후보 영역의 검출 단계, 얼굴/비얼굴의 검출 단계 그리고 얼굴의 인식 단계로 구성되어 있다. 각각의 단계별로 SVM을 적용하였고, 각 SVM은 오프라인상의 학습 부분과 온라인상의 테스트 부분으로 구성되어 있고 SVM의 QP 최적화 문제를 해결하기 위해 학습 알고리즘인 SMO을 적용하였다. 팬(Pan) 틸트(Tilt)제어가 가능한 저가형 웹카메라를 이용하여 자동으로 얼굴 위치를 추적 이동하면서 얼굴 인식을 수행하였다.