• 한국정보컨버전스학회:학술대회논문집
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• 한국정보컨버전스학회 2008년도 International conference on information convergence
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• pp.145-150
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• 2008

This thesis explores the problem of reconstructing a three-dimensional(3D) scene given a set of images or image sequences of the scene. It describes efficient methods for the 3D reconstruction of static and dynamic scenes from stereo images, stereo image sequences, and images captured from multiple viewpoints. Novel methods for image-based and volumetric modelling approaches to 3D reconstruction are presented, with an emphasis on the development of efficient algorithm which produce high quality and accurate reconstructions. For image-based 3D reconstruction a novel energy minimisation scheme, Iterated Dynamic Programming, is presented for the efficient computation of strong local minima of discontinuity preserving energyy functions. Coupled with a novel morphological decomposition method and subregioning schemes for the efficient computation of a narrowband matching cost volume. the minimisation framework is applied to solve problems in stereo matching, stereo-temporal reconstruction, motion estimation, 2D image registration and 3D image registration. This thesis establishes Iterated Dynamic Programming as an efficient and effective energy minimisation scheme suitable for computer vision problems which involve finding correspondences across images. For 3D reconstruction from multiple view images with arbitrary camera placement, a novel volumetric modelling technique, Embedded Voxel Colouring, is presented that efficiently embeds all reconstructions of a 3D scene into a single output in a single scan of the volumetric space under exact visibility. An adaptive thresholding framework is also introduced for the computation of the optimal set of thresholds to obtain high quality 3D reconstructions. This thesis establishes the Embedded Voxel Colouring framework as a fast, efficient and effective method for 3D reconstruction from multiple view images.

• 한국음향학회지
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• 제24권8호
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• pp.492-497
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• 2005

본 논문에서는 오디오 분야에서 가장 대중적인 압축 방식인 MP3 공격에 강인한 워터마킹 방법을 제안한다. 일반적인 주파수 도메인에서의 워터마킹 방법인 Cox의 스프레드 스펙트럼 방법에서는 DCT후 값이 큰 저주파수의 계수에 순차적으로 워터마크를 삽입한다. 제안한 방법에서는 MP3 공격시 손실되는 주파수 계수를 통계적으로 조사하여, 손실이 덜한 순서를 정한 후 이에 맞추어 계수에 워터마크를 삽입하는 방법을 제안한다. 다양한 음원에 대하여 실험한 결과, 제안한 방법은 Cox의 방법에 비해 워터마크의 보존하고 원본 음원의 왜곡을 줄이는 두가지 측면 모두 좋은 결과를 나타내었다.

• 한국비블리아학회지
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• 제6권1호
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• pp.5-46
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• 1984

Today, we have often heard that information is a national resources, perhaps our most important national resources, and that government should recognize this and develop a national policy for the effective management and use of information. But traditionally the library has played a rather passive role in selecting, acquiring, preserving and transfering information. Now we have faced greater and much more diverse and more urgent demand from users and we have to cope effectively with a massive increase in volume and in cost in selecting, acquiring, storing and retrieving information. Individual libraries can no longer keep pace with the published outputs of the world. The solution of these problems lies in "national planning and in cooperation through inter-library cooperation and in the application of data processing to library operations." Also at the national level lies the responsibility for total bibliographic control of the national information output and for the interfacing of this with other national and international systems; for the development, adoption and maintenance of, standards in all areas affecting library work; for the provision of services based on centrally created and maintained bibliographic data files, and for planning and policy development of the national information system.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.105-105
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• 2021

본 연구에서는 2차원 비선형 천수모형과 수심평균된 스칼라 이송모형을 해석하는 수치모형에 대해 기술하였다. 수치모형의 정확성을 보장함과 동시에 안정성을 높이기 위해 유한체적법, 플럭스 재구성 및 minmod 제한자를 사용하였다. 비선형 천수방정식의 이송항과 바닥 경사항은 계산된 수심의 양수 보존과 흐름의 정상 상태를 보장하기 위한 second order well-balanced positivity preserving central-upwind method를 이용하여 수치적으로 이산화되었다. 마찬가지로, 이송-확산 방정식 내 이송항은 동일한 2차 풍상차분법을 통해 수치적으로 풀이하였다. 격자점 경계면에서의 불연속으로 인한 수치진동을 방지하기 위해 이송항의 계산에 포함된 보존항의 차이로 인해 발생하는 스칼라의 수치확산을 최소화하기 위해 무차원의 비소산함수를 도입하였다. 또한, 확산항은 유한차분법을 이용하여 이산화하였다. 제안된 수치모형은 시간미분항의 계산을 위해 오일러 기법을 적용하여 계산된 수심 및 스칼라의 양수 보존여부와 함께 정지된 흐름의 정상 상태의 보존여부를 확인하였다. 제안된 수치모형의 해석 정확성을 평가하기 위해 1, 2차원 공간 내 다양한 흐름 조건에서의 해석해를 이용한 3개의 벤치마크 테스트를 수행하였다. 평균 제곱근 오차(Root Mean Squared Error, RMSE)를 산정하여 수치모형의 성능을 정량적으로 평가하였으며, 비소산함수를 적용함에 따라 스칼라의 수치확산이 감소하게 되었음을 확인하였다. 또한, 세 차례의 벤치마크 테스트 결과는 공통적으로 수치모형에 의해 계산된 결과값이 비소산함수를 고려함에 따라 해석해와 잘 일치함을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권6호
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• pp.1462-1477
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• 2024

With the evolving complexity of connected vehicle features, the volume and diversity of data generated during driving continue to escalate. Enabling data sharing among interconnected vehicles holds promise for improving users' driving experiences and alleviating traffic congestion. Yet, the unintentional disclosure of users' private information through data sharing poses a risk, potentially compromising the interests of vehicle users and, in certain cases, endangering driving safety. Federated learning (FL) is a newly emerged distributed machine learning paradigm, which is expected to play a prominent role for privacy-preserving learning in autonomous vehicles. While FL holds significant potential to enhance the architecture of the Internet of Vehicles (IoV), the dynamic mobility of vehicles poses a considerable challenge to integrating FL with vehicular networks. In this paper, a novel clustered FL framework is proposed which is efficient for reducing communication and protecting data privacy. By assessing the similarity among feature vectors, vehicles are categorized into distinct clusters. An optimal vehicle is elected as the cluster head, which enhances the efficiency of personalized data processing and model training while reducing communication overhead. Simultaneously, the Local Differential Privacy (LDP) mechanism is incorporated during local training to safeguard vehicle privacy. The simulation results obtained from the 20newsgroups dataset and the MNIST dataset validate the effectiveness of the proposed scheme, indicating that the proposed scheme can ensure data privacy effectively while reducing communication overhead.

• Journal of Gastric Cancer
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• 제20권3호
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• pp.277-289
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• 2020

Purpose: To evaluate the feasibility and safety of intracorporeal overlapping gastrogastrostomy between the proximal anterior wall and antrum posterior wall (PAAP; PAAP anastomosis) of the stomach in minimally invasive pylorus-preserving gastrectomy (PPG) for early gastric cancer (EGC). Materials and Methods: From December 2016 to December 2019, 17 patients underwent minimally invasive PPG with PAAP anastomosis for EGC in the high body and posterior wall of the stomach. Intraoperative gastroscopy was performed with the rotation maneuver during proximal transection. A longer antral cuff (>4-5 cm) was created for PAAP than for conventional PPG (≤3 cm) at the point where a safe distal margin and good vascular perfusion were secured. Because the posterior wall of the proximal remnant stomach was insufficient for intracorporeal anastomosis, the anterior wall was used to create an overlapping anastomosis with the posterior wall of the remnant antrum. The surgical and oncological outcomes were analyzed, and the stomach volume was measured in patients who completed the 6-month follow-up. The results were compared to those after conventional PPG (n=11 each). Results: PAAP anastomosis was successfully performed in 17 patients. The proximal and distal resection margins were 2.4±1.9 cm and 4.0±2.6 cm, respectively. No postoperative complications were observed during the 1-year follow-up esophagogastroduodenoscopy (n=10). The postoperative remnant stomach (n=11) was significantly larger with PAAP than with conventional PPG (225.6±118.3 vs. 99.1±63.2 mL; P=0.001). The stomach length from the anastomosis to the pylorus was 4.9±2.4 cm after PAAP. Conclusions: PAAP anastomosis is a feasible alternative for intracorporeal anastomosis in minimally invasive PPG for highly posteriorly located EGC.

• Archives of Reconstructive Microsurgery
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• 제9권2호
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• pp.172-178
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• 2000

With esthetic concern in the reconstruction of skin and soft tissue defects of face, the use of local flap has been the method of choice. However, when there is extensive tissue loss in the face, local flaps do not provide satisfactory results. The amazing development of microsurgical technique has decreased the percentage of free flap failure, thus making free flap use in reconstruction of facial soft tissue defects. Many free flaps has been applied for reconstruction of face defects. Especially, the radial forearm flap has numerous advantages with which facial reconstruction is made possible. But, its disadvantages are ; the sacrifice of one major artery supplying the hand and donor site complications. In order to circumvent these disadvantages, we employed posterior interosseous artery(PIA) forearm free flap for the reconstruction of the face defects. The posterior interosseous forearm island flap was first described by Zancolli and Angrigiani(1985). Currently, the PIA island flap and free flap have been used for hand reconstructions. The disadvantages of the PIA flap are ; the small caliber of the pedicle, different locations of the perforating branches, and the proximity of the motor branch of the radial nerve. But, its advantages lies in preserving the major artery of the hand, minimal donor site morbidity, and fairly well matched skin texture and color, and that the flap volume is sufficient, not too bulky with convenient handling. By using this flap, we performed 1 case of tumor resection and 1 case of traumatic defect. From our experiences we conclude that it is one of many useful methods in the reconstruction of the skin and soft tissue defects of the face. We also have discussed advantages and some limitations of various free flaps for reconstruction of the face.

• 정보관리학회지
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• 제34권4호
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• pp.293-320
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• 2017

본 연구는 지역방송국들의 기록관리 현황을 분석하고 개선방안을 모색하는 것을 목적으로 한다. 이를 위해 분석의 기준점이 되어 줄 KBS서울총국을 비롯하여 KBS 지역방송국 1곳, MBC 지역방송국 1곳, 지역민방 2곳을 방문하여 담당자와의 면담을 통한 현황 조사를 실시하였다. 분석 결과, 대부분의 지역방송국은 디지털로 생산되어 송출된 방송영상물은 방송국 내 서버를 통해 비교적 체계적으로 보관하고 있는 것으로 나타났다. 그러나 이들은 과거에 생산된 아날로그 자료에 대한 디지털화 작업을 실시하지 않고, 보유 기록물의 수량조차 정확하게 파악하지 못하고 있었다. 게다가 보존설비나 검색장비가 낙후되어 기록물에 대한 기본적인 보존과 이용에 있어서 어려움이 많은 것으로 나타났다. 본 연구에서는 이러한 결과를 바탕으로 방송국 자체 기록관리 규정 마련, 목록 작성을 통한 보유 기록물 수량 파악, 아날로그 기록에 대한 디지털화 작업 실시, PD들에 대한 메타데이터 교육 등의 개선방안을 제안하였다.

• Journal of Trauma and Injury
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• 제23권1호
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• pp.16-20
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• 2010

Purpose: High-grade (III, IV, V) renal injury may need interventional management. We investigated whether the selective embolization of the renal artery is effective for the treatment of major renal injury in comparison with emergency renal exploration. Methods: We retrospectively reviewed the medical and radiologic records of patients who underwent surgery or embolization for renal injury (Grade III, IV, V) between January 1990 and December 2007. We analyzed the change in treatment method before and after 2000, the blood pressure, the hemoglobin at the time of visit, the hospital days and the complications in patients who received surgery or embolization. Preserved renal functions of the embolized kidneys were identified by using enhanced CT. Results: Cases of surgery and embolization were 37 and 13, respectively: 5 and 4 in renal injury grade III, 17 and 6 in grade IV and 13 and 3 in grade V. Cases of surgery and embolization were 33 and 1 before 2000 and 2 and 12 after 2000, repectively: embolizations increased after 2000. No significant differences in mean diastolic pressure, hemoglobin, hospital days and complications existed between the surgery and the embolization groups (p>0.05). However, the transfusion volume was significantly smaller in the embolization group (p<0.05). One postoperative complication occurred in the surgery group. We identified the preserved renal functions of the embolized kidney by using enhanced CT. Conclusion: Embolization could be one treatment method for high-grade renal injury. Thus, we might suggest selective embolization a useful method for preserving the renal function in cases of high-grade renal injury.

• 대한두경부종양학회지
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• 제25권2호
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• pp.119-122
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• 2009

Objectives : Ablation of carcinoma of the tongue leads to deficits in speech and swallowing, but none to date has provided all of the qualities of mobility and sensation to simulate the complex function of the tongue. The authors evaluated postoperative swallowing and pronouncing function in patients who underwent tongue reconstruction using free flap. Material and Methods : This is a retrospective review documenting the outcome of 42 patients between January of 1991 and August of 2008. We classified patients according to the size of resection of the tongue like as 7 partial glossectomy, 25 hemiglossectomy, 2 subtotal glossectomy, and 8 total glossectomy. Swallowing function was graded into 4 point scale and pronouncing function was analyzed using picture consonant articulation test. Aspiration was evaluated with videofluoroscopic swallowing study. Results : The average points for swallowing function were 3.43 in partial glossectomy, 3.52 in hemiglossectomy, 3 in subtotal glossectomy, and 2.63 in total glossectomy. The percentage of consonants correct showed 76.5% in partial glossectomy, 72.29% in hemiglossectomy, 47.69% in subtotal glossectomy, and 29.94% in total glossectomy. Aspiration was noted in 3 patients(1 hemiglossectomy and 2 total glossectomy) and 2 total glossectomy patients were taken permanent feeding gastrostomy. Conclusion : Free flap gave us proper volume in tongue reconstruction and showed good result in preserving swallowing function. Swallowing function difference according to the size of defect showed no statistical significance, whereas articulation function was shown to decrease in accuracy as the size of defect was larger.