• 한국정보처리학회논문지
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• 제7권3호
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• pp.1013-1020
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• 2000

In this paper, we propose an algorithm which segments hierarchically blocks of image using discrete cosine transform(DCT) and execute finite-state vector quantization (FSVQ) for each block. Using DCT coefficient feature, image is segmented hierarchically to large smooth block and small edge block, then the block hierarchy informations are transmitted. The codebooks are respectively constructed for each hierarchical blocks, the encoder transmits codeword index using FSVQ for reducing encoded bit with hierarchical segmentation. Compared with side match VQ(SMVQ) and hierarchical FSVQ(HFSVQ) algorithm, about Zelda and Boat image, the new algorithm shows better picture quality with 1.97dB and 2.85 dB difference as to SMVQ, 1.78dB and 1.85dB diffences as to HFSVQ respectively.

• 방송공학회논문지
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• 제24권5호
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• pp.785-790
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• 2019

본 논문에서는 적응적 중첩 블록 움직임 보상 방법을 이용한 새로운 양방향 프레임 율 향상 방법을 제안한다. 제안한 방법에서는 참조 영역의 움직임 복잡도에 기반한 적응적 중첩 블록 음직임 보상 방법이 사용된다. 움직임 복잡도는 이전에 부호화된 움직임 추정과정에서 판단되므로 중첩 블록 움직임 보상 방법에 적응적 기법을 추가적인 계산 복잡도 없이 적용 가능하다. 실험결과는 제한한 방법이 기존 방법에 비해 객곽적, 주관적 화질에서 우수함을 보여준다.

• 한국통신학회논문지
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• 제33권11C호
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• pp.925-931
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• 2008

동영상 표준안 H.264/AVC에서 가변 블록 모드 알고리즘은 압축 성능을 향상시키나 다양한 블록 모드와 모드 결정을 위해 방대한 계산을 필요로 한다. 한편, 결정된 인터 블록 모드들은 블록 영상의 복잡도에 의존하여 복잡한 매크로블록일수록 블록 크기는 더 작아지고 있다. 본 논문은 고속 인터 블록 모드 결정 알고리즘을 제안한다. 제안된 알고리즘은 영상 복잡도를 이용해 유효 인터 블록 모드를 결정 가능성이 큰 블록 모드로 제한하고, 유효블록 모드들에서만 움직임 추정 및 율-왜곡 최적화를 수행한다. 거기에 $16{\times}16$ 블록 모드만을 갖는 유효 블록 모드들에는 고속 움직임 추정 알고리즘인 PDE (partial difference elimination)를 적용시키고 있다. 제안된 알고리즘의 성능 평가를 위해 참조 소프트웨어 JM 9.5에서 화질, 비트율, 부호화 시간이 기존 알고리즘과 비교되었다. 실험 결과는 제안된 알고리즘이 평균 움직임 추정 시간의 약 24.12%를 감소시키며 화질과 비트량을 각각 -0.02dB와 -0.12% 정도로 유지시킬 수 있는 것을 보여주었다.

• The Korean Journal of Pain
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• 제36권2호
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• pp.195-207
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• 2023

Background: This study aimed to compare the effectiveness of the pericapsular nerve group (PENG) block and intra-articular injection (IAI) of steroid-bupivacaine in the treatment of hip osteoarthritis (OA). Methods: After randomization, patients received either a PENG block or IAI under ultrasound-guidance. Clinical evaluations were recorded at baseline, day 1, and weeks 1, 4, and 8 post-intervention. The numerical rating scale (NRS), Western Ontario and McMaster Universities Arthritis Index (WOMAC), Harris Hip Scale (HHS) scores, pain medication use determined by a quantitative analgesic questionnaire, and patient satisfaction were evaluated. Results: Sixty patients were included in this study. NRS scores improved significantly for both groups during the follow-up compared to pretreatment (P < 0.001), with better pain scores for the PENG group (P < 0.001) at day 1 with larger effect size (Cohen's d = 4.62), and IAI group at 4 (Cohen's d = 5.15) and 8 (Cohen's d = 4.33) weeks (P < 0.001). There was no significant difference in pain medication consumption (P = 0.499) and patient satisfaction (P = 0.138) between groups. Patients in the IAI group experienced significant improvement in HHS (Cohen's d = 2.16, P = 0.007) and WOMAC (Cohen's d = 1.02, P = 0.036) scores at 8 weeks compared to the PENG group. Conclusions: The ultrasound-guided PENG block provides effective pain relief which improves functionality and quality of life in hip OA patients up to 2 months. The PENG block can be considered an easy, safe, and useful alternative treatment modality for hip OA.

• 정보처리학회논문지C
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• 제15C권3호
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• pp.149-156
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• 2008

JPEG2000은 차세대 이미지 압축 포맷으로 JPEG에 비하여 우수한 압축률과 화질을 제공할 수 있다. JPEG2000 이미지를 커버 오브젝트로 사용하는 lazy-mode 스테가노그라피는 압축과정에서 발생하는 정보 손실에 의해 메시지가 손실되지 않도록 제안된 알고리즘으로 많은 양의 메시지 삽입이 가능하다. 그러나 이 방법은 메시지 삽입으로 인하여 코드블럭 노이즈 분산의 변화를 발생하게 되고, 이러한 특징을 기반으로 하는 Hilbert-Huang 변환 (HHT) 기반의 스테거낼리시스에 의하여 메시지 삽입여부가 탐지될 수 있다. 본 논문에서는 코드블럭 노이즈 분산의 변화를 예측하고, 이를 최소화하도록 메시지를 삽입하여 HHT 기반 스태거낼리시스에 의해 탐지되지 않는 새로운 JPEG2000 스테가노그라피 알고리즘을 제시한다. 코드블록 노이즈 분산의 변화를 예측하기 위하여 low precision code-block variance와 low precision code-block noise variance를 활용하였다. 또한 메시지 삽입 후의 높은 영상 화질을 유지하기 위하여 JPEG2000의 quality layer 정보를 활용하였다. 제안한 알고리즘의 성능을 보이기 위하여 2048장의 다양한 영상에 대하여 분석을 수행하였고, 이를 통하여 HHT 기반 스태거낼리시스 방법에 안전함을 증명하였다.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.519-528
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• 2016

In order to achieve fast computational speed with good visual quality of output video, we propose a frequency domain based new fractal video compression scheme. Normalized cross correlation is used to find the structural self similar domain block for the input range block. To increase the searching speed, cross correlation is implemented in the frequency domain using FFT with one computational operation for all the domain blocks instead of individual block wise calculations. The encoding time is further minimized by applying rotation and reflection DFT properties to the IFFT of zero padded range blocks. The energy of overlap small size domain blocks is pre-computed for the entire reference frame and retaining the energies of the overlapped search window portion of previous adjacent block. Quadtree decompositions are obtained by using domain block motion compensated prediction error as a threshold to control the further partitions of the block. It provides a better level of adaption to the scene contents than fixed block size approach. The result shows that, on average, the proposed method can raise the encoding speed by 48.8 % and 90 % higher than NHEXS and CPM/NCIM algorithms respectively. The compression ratio and PSNR of the proposed method is increased by 15.41 and 0.89 dB higher than that of NHEXS on average. For low bit rate videos, the proposed algorithm achieve the high compression ratio above 120 with more than 31 dB PSNR.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.626-630
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• 2005

This paper presents a novel Intelligent-Welding-Carriage (IWC) for automation of curved block in shipbuilding. The curved block is usually used in both front and back side of the ship. In curved block root gap is big, $1{\sim}7$ [mm] and inclination, $0{\sim}30$ [deg]. Since available conventional carriage type is limited to use below root gap of 3 [mm], only manual welding is employed in curved block. To adopt an IWC in curved block, it requires control of the welding conditions, i.e., voltage, current and travel speed, with respect to root gap and inclination to achieve good welding quality. In this paper, an IWC is developed for automization of welding operation to accommodate gap and inclination. Kinematics model and dynamics using Lagrangian formulation of the manipulator is introduced. IWC utilizes a database to perform accurate welding. The database is programmed based on numerous experimental test results with respect to gap, inclination, material, travel speed, weaving condition, voltage, and current. Finally, experimental result using PID control is addressed for verify the trajectory tracking accuracy of end-effector.

• 한국CDE학회논문집
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• 제15권1호
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• pp.1-10
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• 2010

Recently, a shipyard is making every effort to efficiently manage equipments of resources such as a gantry crane, transporter, and so on. So far block lifting scheduling of a gantry crane has been manually performed by a manager of the shipyard, and thus it took much time to get scheduling results and moreover the quality of them was not optimal. To improve this, a block lifting scheduling system of the gantry crane using optimization techniques was developed in this study. First, a block lifting scheduling problem was mathematically formulated as a multi-objective optimization problem, considering the minimization of travel distance at an idle state and wire replacement during block lifting. Then, to solve the problem, a meta-heuristic optimization algorithm based on the genetic algorithm was proposed. To evaluate the efficiency and applicability of the developed system, it was applied to an actual block lifting scheduling problem of the shipyard. The result shows that blocks can be efficiently lifted by the gantry crane using the developed system, compared to manual scheduling by a manager.

• Imaging Science in Dentistry
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• 제45권2호
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• pp.117-122
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• 2015

Purpose: Panoramic radiographs taken using conventional chin-support devices have often presented problems with positioning accuracy and reproducibility. The aim of this report was to propose a new bite block for panoramic radiographs of anterior edentulous patients that better addresses these two issues. Materials and Methods: A new panoramic radiography bite block similar to the bite block for dentulous patients was developed to enable proper positioning stability for edentulous patients. The new bite block was designed and implemented in light of previous studies. The height of the new bite block was 18 mm and to compensate for the horizontal edentulous space, its horizontal width was 7 mm. The panoramic radiographs using the new bite block were compared with those using the conventional chin-support device. Results: Panoramic radiographs taken with the new bite block showed better stability and bilateral symmetry than those taken with the conventional chin-support device. Patients also showed less movement and more stable positioning during panoramic radiography with the new bite block. Conclusion: Conventional errors in panoramic radiographs of edentulous patients could be caused by unreliability of the chin-support device. The newly proposed bite block for panoramic radiographs of edentulous patients showed better reliability. Further study is required to evaluate the image quality and reproducibility of images with the new bite block.

• The Korean Journal of Pain
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• 제34권3호
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• pp.271-287
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• 2021

Background: Postoperative pain management is crucial for patients undergoing total knee arthroplasty (TKA). There have been many recent clinical trials on post-TKA peripheral nerve block; however, they have reported inconsistent findings. In this meta-analysis, we aimed to comprehensively analyze studies on post-TKA analgesia to provide evidence-based clinical suggestions. Methods: We performed a computer-based query of PubMed, Embase, the Cochrane Library, and the Web of Science to retrieve related articles using neurothe following search terms: nerve block, nerve blockade, chemodenervation, chemical neurolysis, peridural block, epidural anesthesia, extradural anesthesia, total knee arthroplasty, total knee replacement, partial knee replacement, and others. After quality evaluation and data extraction, we analyzed the complications, visual analogue scale (VAS) score, patient satisfaction, perioperative opioid dosage, and rehabilitation indices. Evidence was rated using the Grading of Recommendations Assessment, Development, and Evaluation approach. Results: We included 16 randomized controlled trials involving 981 patients (511 receiving peripheral nerve block and 470 receiving epidural block) in the final analysis. Compared with an epidural block, a peripheral nerve block significantly reduced complications. There were no significant between-group differences in the postoperative VAS score, patient satisfaction, perioperative opioid dosage, and rehabilitation indices. Conclusions: Our findings demonstrate that the peripheral nerve block is superior to the epidural block in reducing complications without compromising the analgesic effect and patient satisfaction. Therefore, a peripheral nerve block is a safe and effective postoperative analgesic method with encouraging clinical prospects.