• 디지털콘텐츠학회 논문지
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• 제10권2호
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• pp.357-365
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• 2009

사용자가 느끼는 QoS를 최대화하면서 네트워크 대역폭의 특성을 효율적으로 활용하기 위해서는 네트워크의 패킷 손실과 대기행렬의 지연 시간을 구체적으로 예측이 필요하다. 네트워크의 자원이 충분치 않은 무선 네트워크 환경의 경우 예측은 특히 중요한 문제로 부각된다. 본 연구는 무선 네트워크의 성능 모델을 개발하는 것을 목표로 하고 있다. 실험을 위해서 실제 운영 중인 무선 네트워크 환경에서 패킷 흐름 자료를 수집하였다. 무선 환경에서의 패킷 개수 공정과 대역폭 공정은 장기 기억 특성을 갖고 있는 것으로 나타났다. 실험을 통해서 네트워크 트래픽의 주요 성능 변수들을 추출해 냈고, 대기 시간과 버퍼 오버플로우 확률에 대한 분석적 모델을 개발하였다. 프랙탈 브라운 운동 (FBM)을 이용한 대기 행렬의 꼬리 확률을 얻었고, 대기행렬의 길이 모델을 통해서 평균대기 지연을 표현하였다. 실측 데이터를 활용하여 개발한 성능 모델이 IEEE 802.11b 네트워크 트래픽의 물리적 특성을 잘 표현하고 있음을 알 수가 있다

• 디지털콘텐츠학회 논문지
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• 제9권3호
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• pp.389-398
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• 2008

청각장애우들과 일반인과의 커뮤니케이션을 위한 구화체계가 연구되고 있지만 사회적인 무관심과 시장성의 결여로 기존 교사가 일일이 지도하는 비효율적 교육 방식으로 진행되고 있다. 이러한 단점을 극복하기위하여 3차원 애니메이션 및 디지털 테크놀로지 기술을 활용한 콘텐츠를 개발이 필요하다. 캐릭터 제작을 위한 표준얼굴 및 표준구형 조사를 위해 국내 서울 및 경기지역 초등학교 $3{\sim}6$학년 학생의 얼굴관련 데이터를 충분히 수집하여 해당 연령층 학생들의 얼굴과 구형에 대한 표준을 도출하였다. 이러한 자료는 청각장애우를 위한 콘텐츠개발의 기초자료 뿐 아니라 실질적으로 적용할 수 있는 표준치수 및 표준 형태를 제공할 수 있다. 캐릭터 구화 애니메이션 시스템은 3D캐릭터 애니메이션을 응용하여 대화를 이해하고 자신의 의사표현을 교육하는 시스템으로 3D 기술과 모션캡쳐를 접목시켜 가정 및 특수교육 기관에서 언어교육이 필요한 청각장애아동들의 언어교육에 효과적인 학습을 지원한다.

• 대한방사선기술학회지:방사선기술과학
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• 제21권1호
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• pp.29-34
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• 1998

The purpose of simple abdomen erect projection is to see the fluid level which indicates gastrointestinal ileus or free air due to perforation. we do not have to insist on low kVp technique in simple abdomen erect position as long as we can detect the fluid level and free air shadow. Therefore, the author tried to decrease patient dose by high kVp technique and to improve the image quality due to motion artifact by reduction of exposure time. [Methods] Experiment 1. * screen/film SRO1000/HRH * exposure factor : $140\;kvp{\pm}5\;kv$ with added filters, 200 mA, 0.01 sec * phantom : Acryles : 15.0 cm(equivalent to 17 cm body thickness) 17.5 cm(equivalent to 21 cm body thickness) 20.0 cm (equivalent to 25 cm body thickness) With the exposure factor for same film density($D=0.8{\pm}0.1$) and with the materials above, we tried to find out entrance skin dose and gonad dose for both male and female. Experiment 2. Burger's phantom radiography were checked to see whether there was any change of image quality according to the kVp and the added filters. Experiment 3. Using rotating meter(self made), we examined the motion artifact and the exposure time limitation. [Results and conculution] 1. Using high voltage technique of 140 kVp with added filter, Skin dose, testicle dose and ovary dose decrease to 89.3%, 47% and 71.4% respectively compare to 70 kVp technique, 2. No great changes of Burger's phantom image has detected as from 70 kVp to 140 kVp and the air hole size of Burger's phantom over 0.028 cc(Diameter 3 mm, hight 4 mm) can be distinghished. 3. 0.01 sec(1 pulse) exposure time is possible in the single phase full wave rectification that why we can quitely reduce the unsharness caused by patient's movement.

• 대한통합의학회지
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• 제10권3호
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• pp.13-25
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• 2022

Purpose : The purpose of this study was to investigate the effects of combined cervical stabilization exercise (CSE) and stretching exercise (SE) on office workers with forward head posture (FHP). Methods : A total of 32 office workers with forward head posture were randomly assigned to experimental (n=16) and control (n=16) groups. The experimental group underwent combined CSE and SE, and the control group underwent cervical self-myofascial release and SE. Both groups performed exercises for 40 min per day, thrice per week for a total of 6 weeks. Craniovertebral angle (CVA), respiration, disability, and joint range of motion (ROM) before and 6 weeks after intervention were measured and compared. Results : There was no significant between-group difference in the general characteristics (p>.05). The intra-group comparison showed significant differences in the visual analog scale (VAS) and neck disability index (NDI) of both groups post-intervention (p<.05). CVA and forced expiratory volume in 1 seconds (FEV₁) were significantly improved post-intervention in the experimental group only (p<.05). In the experimental group, all ROM variables were significantly improved post-intervention. In contrast, in the control group, all ROM variables improved significantly post-intervention, except for extension (p<.05). The inter-group comparison showed significant differences in NDI, left lateral flexion, right lateral flexion, and left rotation between the two groups (p<.05). Conclusion : The combination of CSE and SE, which stabilizes the cervical spine, had positive effects on cranial rotation angle, respiration, disability, and joint ROM in office workers with forward head posture. Therefore, the combination of the two exercises may be an effective option to reduce symptoms and prevent postural problems in office workers with FHP.

• Clinics in Shoulder and Elbow
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• 제25권4호
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• pp.311-320
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• 2022

Background: The outcomes of patients 50-55 years old or younger undergoing prosthetic shoulder arthroplasty (PSA) may not generalize to younger patients. We report outcomes following PSA in a consecutive series of patients 40 years or younger. We hypothesize that total shoulder arthroplasty (TSA) provides better outcome and durability than resurfacing hemiarthroplasty (RHA). Methods: Patients were stratified by diagnosis and surgical procedure performed, RHA or TSA. Active range of motion and self-assessed outcome were evaluated preoperatively and at final follow-up. Results: Twenty-nine consecutive PSAs were identified in 26 patients, comprising 9 TSAs and 20 RHAs, with a minimum of 2-year follow-up. Twelve PSAs were performed for chondrolysis. Mean active forward elevation, abduction, external rotation, and internal rotation improved significantly (p<0.001 for all). Mean pain score improved from 6.3 to 2.1, Simple Shoulder Test from 4.0 to 9.0, and American Shoulder and Elbow Surgeons score from 38 to 75 (p<0.001 for all). Patients undergoing RHA and TSA had similar outcomes; but three RHAs required revision, two of these within 4 years of implantation. Four of five patients undergoing revision during the study period had an original diagnosis of chondrolysis. Conclusions: PSA in young patients provides substantial improvement in active range of motion and patient reported outcomes irrespective of diagnosis and glenoid management. However, patients undergoing RHA, especially for chondrolysis, frequently require subsequent revision surgery, so that RHA should be considered with caution in young patients and only after shared decision-making and counsel on the risk of early revision to TSA.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권4호
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• pp.1216-1233
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• 2023

Conventional occupational therapy (OT) is conducted under the observation of an occupational therapist, and there are limitations in measuring and analyzing details such as degree of hand tremor and movement tendency, so this important information may be lost. It is therefore difficult to identify quantitative performance indicators, and the presence of observers during performance sometimes makes the subjects feel that they have to achieve good results. In this study, by using the Unity3D and artificial intelligence (AI) speaker, we propose a system that allows the subjects to steadily use it by themselves and helps the occupational therapist objectively evaluate through quantitative data. This system is based on the OT of the sensory integration approach. And the purpose of this system is to improve children's activities of daily living by providing various feedback to induce sensory integration, which allows them to develop the ability to effectively use their bodies. A dynamic OT cognitive assessment tool for children used in clinical practice was implemented in Unity3D to create an OT environment of virtual space. The Leap Motion Controller allows users to track and record hand motion data in real time. Occupational therapists can control the user's performance environment remotely by connecting Unity3D and AI speaker. The experiment with the conventional OT tool and the system we proposed was conducted. As a result, it was found that when the system was performed without an observer, users can perform spontaneously and several times feeling ease and active mind.

• 대한물리의학회지
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• 제17권2호
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• pp.29-40
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• 2022

PURPOSE: This study examined the effects of an exercise program for the thoracic spine and scapula rather than the neck, which is the primary site of pain. METHODS: Thirty-two elementary school teachers with a forward head posture (FHP) were assigned randomly to either the experimental group (n = 16) or the control group (n = 16). The experimental group performed scapular stabilization exercise (SSE) and thoracic extension exercise (TEE), and the control group performed cervical self-myofascial release exercise and stretching exercise. The pulmonary functions, pain, craniovertebral angle (CVA), and cervical range of motion (CROM) were measured before the intervention and six weeks after. RESULTS: The within-group comparisons showed that the VAS and CROM (except for extension) in both groups were significantly different before and after the intervention (p < .05). The changes in the maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), forced vital capacity (FVC), forced expiratory volume at 1 sec (FEV1), and CVA were significant only in the experimental group (p < .05). The between-group comparisons showed a significant difference in the FVC, FEV1, VAS, CVA, and left lateral flexion (p < .05). CONCLUSION: The combination of SSE and TEE in the experimental group was more effective in improving the FHP and breathing ability. Moreover, the experimental group and control combination appeared to be effective in reducing pain and improving the CROM. The combination of SSE and TEE, which are exercises that do not target the cervical spine directly, was effective in improving the posture, respiration, neck pain, and CROM in elementary school teachers with FHP.

• Clinics in Shoulder and Elbow
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• 제6권2호
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• pp.143-148
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• 2003

Objectives: To analyze the postoperative functional outcome of shoulder in patients with arthroscopically assisted repair of large to massive rotator cuff tears with or without acromioplasty and role of acromioplasty. Materials and Methods: From June 1996 to June 2002, twenty six patients with large to massive rotator cuff tears were undergone arthroscopically assisted repair. Mean follow up was over one year. Fourteen were male and twelve were female. Mean age was 51 years old(39-66). Mean duration was 9 months. Acromioplasty was done in 14 cases concomitantly. They were divided into two groups. Group I: arthroscopic cuff repair with acromioplasty(14 cases). Group II: arthroscopic cuff repair without acromioplasty(12 cases). Each shoulder was evaluated at preoperative and final follow-up with Visual Analogue Scale(VAS), University of Pennsylvania Patient self-assessment of pain, University of Pennsylvania Patient self-assessment of function, ASES standardized shoulder assessment form, Simple Shoulder Test, UCLA score and range of motion(ROM). We analyzed the differences between the two groups. Shoulder ROM and acromioplasty were determining factors. Statistics was tested by correlation analysis and repeated measure ANOVA test. Results: At the final follow up, functional outcome and pain were improved but they had no statistical significance between the two groups(p>0.05). Combined procedure, acromioplasty, didn't affect on VAS. UCLA score, University of Pennsylvania Patient self-assessment of pain, University of Pennsylvania Patient self-assessment of function, ASf:S standardized shoulder assessment form and Simple Shoulder Test(p>0.05). In group II, forward flexion and abduction were statistically improved at the final follow up than in group I(p<0.05). Conclusions: It appears that arthroscopic repair is satisfactory procedure in patients with large to massive cuff tears. Combined procedure, acromioplasty, doesn't affect on postoperative functional outcome of shoulder.

• 한국ITS학회 논문지
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• 제13권1호
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• pp.99-108
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• 2014

최근 들어, 차량 제어 기술의 집약체라 할 수 있는 자율 주행 차량에 관한 관심이 증대되고 있다. 특히, 자율 주행 차량의 안정적인 주행과 직결되는 자기 위치 인식 기술에 관한 연구가 꾸준히 진행되어져 왔으며, GPS가 갖는 한계점을 보완하기 위한 다양한 추측항법 기술이 소개되어져왔다. 하지만 기존의 추측항법들은 추가적으로 센서를 장착해야하는 단점과 차량 거동의 급격한 변화로 인하여 자기 위치 인식 정확도가 떨어진다는 단점을 가진다. 따라서 본 논문에서는 기존의 추측항법의 단점을 보완하기 위하여 대부분의 차량에 장착되어 있는 휠속 센서(Wheel Speed Sensor)를 활용하고, 휠속 센서에서 계측된 값을 토대로 타이어 슬립율(Slip ratio)을 추정하여 차량의 급격한 거동 변화에 대응하기 위한 새로운 개념의 슬립율 기반의 추측항법 알고리즘을 개발하였다. 기존의 추측항법 알고리즘과의 성능을 비교 평가하기 위해서 차량의 거동이 급격하게 변화하는 상황이 포함된 시뮬레이션 환경을 구성하여 그 결과를 비교하였다.

• 대한조선학회지
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• 제26권2호
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• pp.32-40
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• 1989

자동위치 확보시스템은 선박이 불규칙 해상에서 작업을 수행할 때 선체의 위치 및 선수를 일정한 작업반경 내에서 유지할 수 있도록 추진기를 자동제어하는 방법이다. 위치확보시스템의 구성은 계측시스템, 제어기시스템, 추진기시스템 및 동력시스템으로 구성된다. 본 논문은 최적제어 기법과 필터링 기법을 이용한 제어기시스템 구성에 관하여 논하였고, 제어시스템 구성을 위한 상태방정식의 정립과정을 서술하였다. 선체의 평면운동은 저주파수 운동과 고주파수 운동의 성분으로 구성되었다고 가정하였다. 저주파수 운동은 추진기에 의한 외력, 조류력 및 2차차수 파랑강제력에 기인하며 고주파수 운동은 1차 차수 파랑강제력에 의해 유기된다. 해상에서 계측되는 신호에는 선체의 운동성분 이외에도 계측오차 성분이 포함된다. 자기동조필터 및 칼만필터를 이용하여 계측신호로부터 저주파수 운동성분과 고주파수 운동성분을 각각 독립적으로 추정하고, 추정된 저주파수 운동성분을 궤환하여 제어를 수행하였다. 제어기는 교란환경 속의 최적제어기인 LQG제어기를 이용하였다. 시뮬레이션을 수행하기 위하여 Wimpey Sealab의 데이타를 이용하였다.