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대화형 멀티미디어 서비스의 지연한계 보장을 위한 적응적 전송률 조절 기법
정욱헌,정광수 한국정보과학회 2012 한국정보과학회 학술발표논문집 Vol.39 No.1D
최근 네트워크 기술의 발달과 모바일 기기 성능의 향상으로 대화형 멀티미디어 서비스에 대한 요구가 증가하고 있다. 대화형 멀티미디어 서비스는 음성과 영상을 실시간으로 주고받는 서비스로 지연에 민감한 특성을 가진다. 따라서 대화형 멀티미디어 서비스의 품질을 보장하기 위해서는 재생 지연한계를 고려해야 한다. 본 논문에서는 대화형 멀티미디어 서비스의 단대단 지연한계를 보장하기 위해서 네트워크와 송신버퍼 그리고 수신버퍼에서 발생하는 지연을 고려하여 전송률을 조절하는 기법을 제안한다. 제안하는 기법은 송신버퍼와 수신버퍼에 지연한계를 설정하고 이를 보장하기 위해 전송률을 조절함으로써 지연한계와 재생의 연속성을 보장하였다. 실힘을 통해 본 논문이 대화형 멀티미디어 서비스의 단대단 지연한계를 보장함을 보였다.
정욱헌,박선아,이재훈,정다정,양우종,강은희,최치봉,장화석,김대현,황수한,한훈,김휘율 대한수의학회 2013 Journal of Veterinary Science Vol.14 No.4
The use of human umbilical cord blood-derived mesenchymal stem cells for cell transplantation therapy holds great promise for repairing spinal cord injury. Here we report the first clinical trial transplantation of human umbilical cord (hUCB)-derived mesenchymal stem cells (MSCs) into the spinal cord of a dog suspected to have fibrocartilaginous embolic myelopathy (FCEM) and that experienced a loss of deep pain sensation. Locomotor functions improved following transplantation in a dog. Based on our findings, we suggest that transplantation of hUCB-derived MSCs will have beneficial therapeutic effects on FCEM patients lacking deep pain sensation.
Improved rat spinal cord injury model using spinal cord compression by percutaneous method
정욱헌,이재훈,정다정,양우종,이아진,최치봉,장화석,김대현,정효진,서현정,황수한,한훈,김휘율,도선희 대한수의학회 2013 Journal of Veterinary Science Vol.14 No.3
Here, percutaneous spinal cord injury (SCI) methods using a balloon catheter in adult rats are described. A balloon catheter was inserted into the epidural space through the lumbosacral junction and then inflated between T9-T10 for 10min under fluoroscopic guidance. Animals were divided into three groups with respect to inflation volume: 20 μL (n = 18), 50 μL (n = 18) and control (Fogarty catheter inserted but not inflated; n = 10). Neurological assessments were then made based on BBB score, magnetic resonance imaging and histopathology. Both inflation volumes produced complete paralysis. Gradual recovery of motor function occurred when 20 μL was used, but not after 50 μL was applied. In the 50 μL group, all gray and white matter was lost from the center of the lesion. In addition,supramaximal damage was noted, which likely prevented spontaneous recovery. This percutaneous spinal cord compression injury model is simple, rapid with high reproducibility and the potential to serve as a useful tool for investigation of pathophysiology and possible protective treatments of SCI in vivo.
HTTP 적응적 스트리밍에서 사용자 체감품질 향상을 위한 부드러운 비디오 품질 조절 기법
정욱헌(Ukheon Jeong),정광수(Kwangsue Chung) 한국정보과학회 2013 정보과학회논문지 : 정보통신 Vol.40 No.5
최근 HTTP 적응적 스트리밍 서비스가 주목 받고 있다. HTTP 적응적 스트리밍 서비스는 TCP를 기반으로 데이터를 전송하기 때문에 빈번한 비디오 품질 변화가 발생하여 사용자 체감품질이 감소되는 문제가 있다. 따라서 사용자 체감품질을 향상시키기 위해서는 평활도(Smoothness)를 고려한 비디오 품질 조절 방법에 대한 연구가 필요하다. 본 논문에서는 HTTP 적응적 스트리밍 서비스의 사용자 체감품질을 향상시키기 위해 SR-HAS(Smooth Rate Adaptation for HTTP Adaptive Streaming) 기법을 제안한다. SR-HAS 기법은 MSD(Media Segment Duration), SFT(Segment Fetch Time) 그리고 클라이언트의 버퍼 상태를 고려하여 비디오 품질을 조절함으로써 품질 변화를 감소시킨다. 실험 결과를 통해 본 논문에서 제안한 SR-HAS기법이 HTTP 적응적 스트리밍 서비스에서 사용자 체감품질을 향상시키는 것을 확인하였다. Recently, HTTP adaptive streaming service is gaining attention. Since the HTTP adaptive streaming service is based on TCP, it reduces the QoE(Quality of Experience) due to the frequent changes of video quality. Therefore, it is necessary to study the video quality control method that takes into account the smoothness in order to improve the QoE in HTTP adaptive streaming services. In this paper, we propose a SR-HAS(Smooth Rate Adaptation for HTTP Adaptive Streaming) scheme in order to improve the QoE in HTTP adaptive streaming services. The SR-HAS scheme reduces the changes of quality by adjusting the video quality based on MSD(Media Segment Duration), SFT(Segment Fetch Time) and the buffer state of client. Through the simulation results, we prove that our scheme improves the QoE in HTTP adaptive streaming services.
Pulmonary Mineralization Secondary to Iatrogenic Hyperadrenocorticism in a Dog
박노운,정욱헌,한재익,엄기동 한국임상수의학회 2014 한국임상수의학회지 Vol.31 No.3
An 11-year-old, intact male Shih Tzu presented with obesity, thin hair coat, and abdominal distention. Thepatient had previously received corticosteroid therapy for dermatitis. Thoracic radiographs showed incidental findingsof a generally diffuse bronchointerstitial pattern and markedly radiolucent pleural lines between the middle and caudallung lobes, but clinical signs related to the thoracic radiographic findings were absent. Echogenicity of the hepaticparenchyma was increased and bilateral adrenal glands were not enlarged on ultrasonography. On computed tomography,the central regions of the lung lobes showed ground-glass attenuation, the peripheral regions of the lung lobes wererelatively hypoattenuated compared with the central regions, and hyperattenuated nodules were distributed throughoutthe pulmonary parenchyma. Iatrogenic hyperadrenocorticism and secondary pulmonary mineralization was diagnosedon the basis of diagnostic imaging and adrenocorticotropic hormone stimulation test.
Dynamic Computed Tomographic Characteristics of a Colorectal Leiomyoma in a Dog
박노운,정욱헌,한재웅,엄기동 한국임상수의학회 2015 한국임상수의학회지 Vol.32 No.2
A 12-year-old neutered male Shih Tzu presented with constipation and dyschezia. Abdominal radiographs showed distension of the descending colon and dorsal compression of the colon by a soft tissue mass. The mass was well-marginated with homogeneous soft tissue attenuation and showed no evidence of metastasis on computed tomography (CT). The dynamic CT showed a consistently mild contrast enhancement. The perfusion and capillary permeability were lower than those of the gluteal muscle. The tentative imaging diagnosis was a benign intrapelvic tumor, which rarely shows angiogenesis. The mass was excised, and a leiomyoma was confirmed by histopathologic examination.
이재훈,양우종,정다정,정욱헌,김대현,이정익,김휘율,장화석,강은희,최치봉,이정익 한국임상수의학회 2009 한국임상수의학회지 Vol.26 No.1
A diaphragm is a musculotendinous partition that separates abdominal and thoracic organs and assists in ventilation. Three dogs were presented after being hit by a car, and one dog was presented with the history of respiratory problems including intermittent dyspnea and coughing. Survey thoracic radiography, positive contrast celiography and sonography revealed traumatic diaphragmatic hernia in three dogs and congenital peritoneopericardial diaphragmatic hernia in one dog. In three dogs including a dog with congenital peritoneopericardial diaphragmatic hernia, herniorrhaphy was performed. Among the three dogs underwent surgery, two dogs with traumatic diaphragmatic hernia recovered uneventfully. However the dog with congenital peritoneopericardial diaphragmatic hernia died from pulmonary edema at 2 days after surgery. Positive-contrast ceilography and ultrasonography provides to investigate the integrity of the diaphragm. Chronic diaphragmatic hernia and concurrent injuries are considered as prognostic factors.