부분 해를 이용한 IRIS 실시간 태스크용 온-라인 스케줄링 알고리즘의 성능향상

심재홍,최경희,정기현 한국정보과학회 2003 정보과학회논문지 : 시스템 및 이론 Vol.27 No.6

본 논문에서는 가치함수를 가지면서 동적으로 도착하는 IRIS(Increasing Reward with Increasing Service) 실시간 태스크들의 총 가치를 최대화하기 위한 온-라인 스케줄링 알고리즘을 제안한다. 본 논문은 스케줄링 알고리즘의 성능향상에 역점을 두고 있으며, 이는 다음 두 가지 아이디어를 기반으로 한다. 첫째, 총가치를 최대화하는 문제는 가치함수들의 최대 도함수 값들 중 최소 값을 찾는 문제를 해결함으로써 풀 수 있다는 것이다. 둘째, 새로운 태스크가 도착하기 전까지 이 전에 스케줄된 태스크들 중 소수만이 실제 실행되고, 나머지는 새로 도착한 태스크와 함께 다시 스케줄링 된다는 사실을 발견하고, 매 스케줄링 시 모든 태스크들을 스케줄링하는 것이 아니라, 일부 태스크들만 스케줄링하자는 것이다. 제안 알고리즘의 성능은 다양한 경우에 대한 모의실험으로 검증되었다. 실험 결과 제안 알고리즘의 계산 복잡도는 최악의 경우 기존 알고리즘과 동일한 O(N2)이지만, 평균적으로 이 보다 낮은 O(N)에 가까운 것으로 확인되었다 In this paper, we propose an on-line scheduling algorithm with the goal of maximizing the total reward of IRIS(Increasing Reward with Increasing Service) real-time tasks that have reward functions and arrive dynamically into the system. We focus on enhancing the performance of scheduling algorithm, which is based on the following two main ideas. First, we show that the problem to maximize the total reward of dynamic tasks can also be solved by the problem to find minimum of maximum derivatives of reward functions. Secondly, we observed that only a few of scheduled tasks are serviced until a new task arrives, and the rest tasks are rescheduled with the new task. Based on our observation, the proposed algorithm doesn't schedules all tasks in the system at every scheduling point, but a part of tasks. The performance of the proposed algorithm is verified through the simulations for various cases. The simulation result showed that the computational complexity of proposed algorithm is O(N2) in the worst case which is equal to those of the previous algorithms, but close to O(N) on the average.

전이성 경막상 척수종양 : 갑상선 기시 Originating from Thyroid

심재홍 대한신경외과학회 1979 Journal of Korean neurosurgical society Vol.8 No.1

We have reported very rare two cases of matastatc spinal cord tumor originating from the thyroid. First case is obtained the best results as early diagnosis and surgical treatment were employed. Second case the least favorable results were obtained in case with rapid progression of neurological feature and multiple involvement at spinal cord and brain. The early diagnosis and treatment often prevent patients from becoming paraplagic. This paper is concerned with the discription of the clinical feature of spinal cord compression by malignant tumors and results of treatment.

SSFNet 기반 사이버 공격 및 탐지를 위한 네트워크 시뮬레이터의 구현

심재홍,정홍기,이철원,최경희,박승규,정기현,Shim, Jae-Hong,Jung, Hong-Ki,Lee, Cheol-Won,Choi, Kyung-Hee,Park, Seung-Kyu,Jung, Gi-Hyun 한국정보과학회 2002 정보과학회 컴퓨팅의 실제 논문지 Vol.16 No.2

가상 공격을 수행하고 이에 따른 네트워크의 행동 변화를 시뮬레이션하기 위하여는 네트워크 구성요소들의 특성을 시뮬레이션 모델에 반영할 수 있어야 하며, 다양한 사이버 공격과 이를 방어하는 시스템들의 특성을 표현할 수 있어야 한다. 본 연구에서는 사이버 공격시 네트워크의 부하가 어떻게 변하는지를 실험하기 위하여, 프로세스 기반 사건 중심 시뮬레이션 시스템인 SSF[9, 10]를 확장 구현하였다. 사이버 공격을 시뮬레이션하기 위해 보안 관련 클래스인 방화벽과 공격용 프로그램을 작성하기 위한 도구들의 모임인 패킷 조작기를 SSF의 구성요소인 SSFNet에 새로이 추가하였다. 이는 보안 체계를 가진 네트워크를 시뮬레이션 가능하게 할 뿐 아니라, 기존 사이버 공격 프로그램을 쉽게 이식하여 시뮬레이션에 적용할 수 있는 장점을 제공한다. 추가된 클래스들의 작동을 검증하기 위하여 가상 네트워크를 구성한 후, 대표적인 서비스-거부 공격인 smurf 공격을 시뮬레이션하고, 이 때의 네트워크의 행동 변화를 관찰하였다. 실험 결과 본 연구에 의하여 개발된 방화벽이나 패킷 조작기가 정상적으로 작동됨을 확인할 수 있었다. In order to simulate cyber attacks and predict network behavior by attacks, we should represent attributes of network components in the simulation model, and should express characteristics of systems that carry out various cyber attacks and defend from these attacks. To simulate how network load may change under the cyber attacks, we extended SSF[9, 10] that is process-based event-oriented simulation system. We added a firewall class and a packet manipulator into the SSFNet that is a component of SSF. The firewall class, which is related to the security, is to simulate cyber attacks, and the packet manipulator is a set of functions to write attack programs for the simulation. The extended SSFNet enables to simulate a network with the security systems and provides advantages that make easy to port already exsiting attack programs and apply them to the simulation evironment. We made a vitual network model to verify operations of the added classes, and simulated a smurf attack that is a representative denial of sevive attack, and observed the network behavior under the smurf attack. The results showed that the firewall class and packet manipulator developed in this paper worked normaly.

지주막하 출현 환자에서 Transcranial Doppler를 이용한 뇌동맥 혈류 속도 측정

심재홍 인제대학교 1998 仁濟醫學 Vol.19 No.2

1997년 1월 1일부터 1997년 6월 30일까지 6개월간 본원 신경외과에 입원하여 수술을 시행하였던 뇌동맥류파열 환자 72예 중 63예에서 중대뇌동맥의 평균 혈류속도를 경두개 도플러 초음파를 이용하여 측정하여, 임상적으로 뇌혈관 연축이 있었던 군 및 뇌전산화단층촬영상 Fisher 등급에 따른 뇌혈관연축정도를 비교 분석하였다. The velocity of blood flow through the middle cerebral arteries was measured by transcranial Doppler sonography in 63 patients with aneurysmal subarachnoid hemorrhage. The velocity became greater from 4th day after the hemorrhage reached a plateau on 6th-11th day and declined there after. The velocity through the arteries of the patients who showed Fisher grade III, IV on CT scan within 3 days after the hemorrhage was significantly greater than that of the patient who showed Fisher grade I, II. The maximum mean velocity in the patients with delayed ischemic deficits was greater than that in the patients without delayed ischemic deficits. Transcranial Doppler ultrasonography makes it possible to measure, noninvasive and repeatly the changes in blood flow velocity that occur with vasospasm.

Recent Advances in Therapeutic Biliary Endoscopy

심재홍 白中央醫療院 2004 仁濟醫學 Vol.25 No.1

Objectives: The goal of the aneurysm surgery is complete circulatory exclusion of the aneurysm without compromise of the normal vessels. Failure to obliterate intracranial aneurysm completely during initial surgery still occurs in spite of recent technical advances. Methods and Materials: Between 1980 and November, 18th 2002, we have performed 2,500 cases aneurysm surgery. Among these, we experienced 29 reoperated cases for the failed initial aneurysm surgery, including 7 intraoperative clip readjustment after intra-operative angiography. Results: Twenty-nine cases were reoperated for the failed surgery. Of them, 7 cases were performed intraoperative angiography and the others(22) were not. 3 cases were performed initial operation in other hospital. The number of location of aneurysm was 15 A-com, 7 ICA and 5 MCA. tec. The causes of operations were vessel occlusion(8), residual neck(7), rebleeding after coating(5), aneurismal filling(3), slipped clip(2) and others. Clinical outcomes were better than in readjustment group after intraoperative angiography; above favorable outcome in 6(85.7%), but 16(72.7%) in group without intraoperative angiography. Conclusion: Reoperative management for failed aneurysm surgery is very difficult because of scar tissue, coating material and previously placed clip etc. Preoperative and postoperative detailed radiological and clinical assessment should be performed to determine the success of surgical treatment. During operative procedure, the use of intraoperative angiography, endoscopy and doppler sonography etc. will reduce the need of another operation and decrease the risk of post operative complications.

뇌동맥류 재수술의 수술치험

심재홍 인제대학교 백병원 2002 仁濟醫學 Vol.23 No.4

Objectives: The goal of the aneurysm surgery is complete circulatory exclusion of the aneurysm without compromise of the normal vessels. Failure to obliterate intracranial aneurysm completely during initial surgery still occurs in spite of recent technical advances. Methods and Materials: Between 1980 and November. 18th 2002, we have performed 2,500 cases aneurysm surgery, Among these, we experienced 29 reoperated cases for the failed initial aneurysm surgery, including 7 intraoperative clip readjustment after intra-operative angiography. Results: Twenty-nine cases were reoperated for the failed surgery. Of them, 7 cases were performed intraoperative angiography and the others(22) were not. 3 cases were performed initial operation in other hospital. The number of location of aneurysm was 15 A-com, 7 ICA and 5 MCA. tec. The causes of operations were vessel occlusion(8, residual neck(7), rebleeding after coating(5), aneurismal filling(3), slipped clip(2) and others. Clinical outcomes were better than in readjustment group after intraoperative angiography; above favorable outcome in 6(85.7%), but 16(72.7%) in group without intraoperative angiography. Conclusion: Reoperative management for failed aneurysm surgery is very difficult because of scar tissue, coating material and previously placed clip etc. Preoperative and postoperative detailed radiological and clinical assessment should be performed to determine the success of surgical treatment. During operative procedure, the use of intraoperative angiography, endoscopy and doppler sonography etc. will reduce the need of another operation and decrease the risk of post operative complication.

비주기적 태스크 서버들을 지원하기 위한 확장된 실시간 스케줄러 모델

심재홍,김영일,최경희,정기현,유해영,Shim, Jae-Hong,Kim, Yeong-Il,Choi, Hyung-Hee,Jung, Gi-Hyun,Yoo, Hae-Young 한국정보처리학회 2001 정보처리학회논문지 A Vol.8 No.1

본 논문은 상위 단계의 태스크 스케줄러와 하위 단계의 스케줄링 Framework으로 구성된 기존의 스케줄러 모델[4,5]을 수정하여, 다양한 비주기적 태스크 서버들을 지원할 수 있는 확장된 스케줄러 모델을 제안한다. 제안 모델은 기존 스케줄링 Framework과 태스크 스케줄러를 기반으로 한다. 그러나 비주기적 태스크 스케줄링을 위해 태스크 스케줄러를 다시 주기적 태스크 제어부와 비주기적 태스크 제어부로 분리하였다. 제안 모델은 대부분의 실시간 커널에서 복잡하게 결합되어 하나의 커널 스케줄러를 구성하던 구성 요소들을 기능별로 재구성이 가능하도록 명확하게 구분함으로써, 커널 하부 메커니즘과는 독립적으로 새로운 스케줄링 알고리즘과 비주기적 태스크 서버들을 구현할 수 있게 했다. Real-Time Linux[6]에 제안된 스케줄러 모델을 구현한 후, 이를 기반으로 다양한 스케줄러와 서버들을 시험적으로 구현하여 보았다. 이를 통해 향후 새로운 알고리즘과 서버를 하부이 복잡한 커널 메커니즘 수정 없이 독립적으로 개발할 수 있음을 확인하였다. 또한 여러 성능 실험을 통해 제안 모델을 기반으로 다양한 스케줄러와 서버를 구현한다 해도 실행시의 부하는 크지 않은 반면, 시스템 재구성과 새로운 스케줄러 개발을 효과적으로 지원할 수 있다는 것을 확인할 수 있었다. This paper proposes an extended scheduler model that is an extension of the existing model proposed already in [4, 5], which consists of upper layer task scheduler and lower layer scheduling framework. However, in order to support aperiodic task scheduling, the task scheduler has been divided into two parts, such as periodic task control component and aperiodic task control component. Thus, the proposed model can support various bandwidth-preserving servers that can service aperiodic tasks. The model distinctly separates a classic monolithic kernel scheduler into several kernel components according to their functionality. This enables system developers to implement a new scheduling algorithm or aperiodic task server independent of complex low kernel mechanism, and reconfigure the system at need. In Real-Time Linux [6], we implemented the proposed scheduling framework representative scheduling algorithms, and server bandwidth-preserving servers on purpose to test. Throughout these implementations, we confirmed that a new algorithm or server could be developed independently without updates of complex low kernel modules. In order to verify efficiency of the proposed model, we measured the performance of several aperiodic task servers. The results showed this the performance of model, which even consisted of two hierarchical components and several modules, didnt have such high run-time overhead, and could efficiently support reconfiguration and scheduler development.

태스크 선택정책에 기반을 둔 IRIS 태스크 스케줄링 알고리즘

심재홍,최경희,정기현 한국정보처리학회 2003 정보처리학회논문지. 컴퓨터 및 통신시스템 Vol.10 No.3

뇌동맥류의 수술시기에 따른 임상적 고찰

심재홍 대한신경외과학회 1984 Journal of Korean neurosurgical society Vol.13 No.2

To evaluate the risk of definitive intracranial microsurgical aneurysm obliteration as a function of the timing of the operative intervention, we retrospectively reviewed 167 consecutive patients in the department of Neurosurgery of Busan Paik's Hospital, Inje medical college, from January 1980, to December 1983. The patients who were operated upon within the first 3 days of their most recent subarachnoid hemorrhage formed the early group; the patients operated upon after the 3 days were considered to have undergone the late surgery. On the base of their clinical outcome the patients were allocated to one of five outcome categories (excellent, good, fair, poor, death) both at the time of their hospital discharge and at their most recent clinical revaluation. The 83% favorable outcome estimated from early operation and 72% from late operation. The mortality was estimated 5% from early operation and estimated 11% from late operation. The optimal timing of surgery for ruptured intracranial aneurysms is currently unknown, but early operation is an effective and reliable method to reduce the occurrence of rebleeding, vasospasm, ischemic complication and medical complication etc. Recently, there has been a resurgence of interest in early operation and increasing numbers of surgeons have been adopting this modality, but prompt, accurate diagnosis and early referral to specialized centers is the only way in which significant advances in reducing the overall morbidity and mortality for majority of patients can be achieved.

`82 민방위행정부문의 역점시책

심재홍 대한지방행정공제회 1982 地方行政 Vol.31 No.341