업무형태 및 시스템구조에 따른 성능지표에 관한 연구

이형봉 湖南大學校 情報通信硏究所 1999 정보통신연구 Vol.9 No.-

Sometimes we are confused at performance data provided by vendors because all of them say they are the best in the world. So, this paper tries to propose some performance index for system selection. Especially the system architecture is very important for specific computing area. This paper decribes three architectures MPP, SMP, Clustered SMP and explains differences between them. Also, this paper analyzes three computing area such as scientific calcuation, OLTP, Data Warehouse and extracts some characteristics of them related with computer architecture. Then, some recommendations are made for each computing area in the point of performance index. Those performance index will help users select computer systems for their own specific computing area.

중등 정보과학 교수학습 시나리오 사례

이형봉 한국과학영재교육학회 2011 과학영재교육 Vol.3 No.3

Most of people including parents of students define a gifted student as a smart student. In general, the smart student, who is called a infant genius, has high level of intelligence quotient, so he learns theory or principle for himself and refute about them from childhood. On the other hand, the gifted student has a very high level of creativity and concentration instead of a high level of intelligence quotient, and he needs a special education to expose the hidden giftedness. Therefore, it is very important to do a proper education for the gifted students. Many of the classrooms for the gifted students in Korea, however, are formed without stern giftedness identification, so the education for the gifted students may be improper. Therefore, it is necessary for the instructional materials to include contents of giftedness identification. In this paper, we introduce a instructional scenario including contents of giftedness identification in computer science, which is applied in Institute of Science-Gifted Education in Gangneung-Wonju National University. 학부모를 포함한 대부분의 사람들은 영재를 뛰어난 학생이라고 정의한다. 이와 같이 뛰어나 보이는 학생들은 지적 능력이 뛰어나 스스로 학습하여 터득함으로써 어려서부터 여러 분야에서 높 은 경지의 이론을 이해하고 설파하는 천재들인 경우가 많다. 그러나, 영재는 천재와 다르게 지적 능 력은 크게 높지 않지만 창의성과 집중력이 뛰어나, 적절한 교육을 실시하면 해당 분야에서 두각을 나 타낼 수 있는 학생으로, 숨어있는 재능의 발굴을 필요로 한다. 따라서, 학생들의 잠재된 영재성과 일 치하는 영재교육이 매우 중요하다. 그런데, 현재 국내 대부분의 영재학급들은 학생들의 잠재된 영재 성 분야에 대한 충분한 탐색과정 없이 학생들의 선택에 따라 형성되고 있어서, 영재성 분야의 불일치 가 존재할 가능성이 크다. 그러므로 영재교육에는 잠재된 재능이 해당 교육분야와 일치하는가를 탐 색하는 과정도 포함되어야 한다. 이 논문에서는 강릉원주대학교 과학영재교육원의 중등 정보과학 영재 학급에서 적용되고 있는 정보과학 분야 영재성 탐색을 겸한 교수학습 시나리오를 소개한다.

SpO2 기반 휴대형 생체 신호 모니터링 시스템 개발

이형봉,박성욱,정태윤 대한임베디드공학회 2013 대한임베디드공학회논문지 Vol.8 No.5

The traditional medical equipments are devices used by medical professionals but not used in public environment. Common people, however, require light-weight medical devices to make healthcare for themselves nowadays. Those medical devices are used to monitor personal health status such as blood pulse, blood pressure, diabetes. Also, some of them are operated in mobile environment called u-healthcare. This paper implements a portable healthcare system composed of SpO2(Saturation of Partial Pressure Oxygen) sensors and a gateway for detecting hypoxemia during people's leasure activity such as climbing or hiking. The SpO2 sensor is designed as watch style to support dynamic exercise and the gateway is designed as necklace style to support the elderly. The result of a performance evaluation shows that the performance of the SpO2 sensor using reflection technology is not lower than that of a clairvoyant styled SpO2 sensor.

SSD FTL의 캐시 메커니즘에 대한 심층 분석 및 개선

이형봉,정태윤 대한임베디드공학회 2020 대한임베디드공학회논문지 Vol.15 No.1

Recently, the capacity of SSD has been increasing rapidly due to the improvement of flash memory density. To take full advantage of these SSDs, first of all, FTL's prompt adaptation is necessary. The FTL is a translation layer existing in SSDs to overcome the drawback of the SSD that cannot be modified in place, and has garbage collection and caching functions in addition to the map table management function. In this study, we focus on caching function, compare and analyze the cache implementation methodologies, and propose improved methods. Typical cache implementations divide the cache into groups, manage and retrieve the caches in the group as a linked list. Thus, searches are made in the order of the linked list. In contrast, we propose a method of sequential searching using the search area group of a cache registered in the map table regardless of the linked list and cache group. Experimental results show that the proposed method has a 2.5 times improvement over the conventional method.

NAND 플래시 변환 계층에서 전력 소모에 영향을 미치는 페이지 캐싱 전략의 비교·분석

이형봉,정태윤,Lee, Hyung-Bong,Chung, Tae-Yun 대한임베디드공학회 2018 대한임베디드공학회논문지 Vol.13 No.3

SSDs that are not allowed in-place update within the allocated page cause another allocation of a new page that will replace the previous page at the moment data modification occurs. This intrinsic characteristic of SSDs requires many changes to the existing HDD-based IO theory. In this paper, we conduct a performance comparison of FTL caching strategy in perspective of cache hashing (Global vs. grouped) and caching algorithm (LRU vs. NUR) through a simulation. Experimental results show that in terms of energy consumption for flash operation the grouped management of cache is not suitable and NUR algorithm is superior to LRU algorithm. In particular, we found that the cache hit ratio of LRU algorithm is about 10% point higher than that of NUR algorithm while the energy consumption of LRU algorithm is about 32% high.

플래시 변환 계층을 위한 DPW-LRU 캐시 교체 알고리즘 분석 및 개선

이형봉,정태윤,Lee, Hyung-Bong,Chung, Tae-Yun 대한임베디드공학회 2020 대한임베디드공학회논문지 Vol.15 No.6

Although flash disks are being used widely instead of hard disks, it is difficult to optimize for effective utilization of flash disks because overwrite in place is impossible and the power consumption and time required for read, write, and erase operations are all different. One of these optimization issues is a cache management strategy to minimize write operations. The cache operates at two levels: an operating system equipped with flash disks and a translation layer within the flash disk. Most studies deal with the operating system-level cache strategy. In this study, we implement and analyse the DPW-LRU algorithm which is one of the recently proposed operating system cache replacement algorithms to apply to FTL, and grope with some improvements. As a result of the experiment, the DPW-LRU algorithm maintained superiority even in the FTL environment, and showed better performance with a slight improvement.

DHP 연관 규칙 탐사 알고리즘을 위한 효율적인 해싱 메커니즘

이형봉 한국정보처리학회 2006 정보처리학회논문지D Vol.13 No.6

Algorithms for mining association rules based on the Apriori algorithm use the hash tree data structure for storing and counting supports of the candidate frequent itemsets and the most part of the execution time is consumed for searching in the hash tree. The DHP(Direct Hashing and Pruning) algorithm makes efforts to reduce the number of the candidate frequent itemsets to save searching time in the hash tree. For this purpose, the DHP algorithm does preparative simple counting supports of the candidate frequent itemsets. At this time, the DHP algorithm uses the direct hash table to reduce the overhead of the preparative counting supports. This paper proposes and evaluates an efficient hashing mechanism for the direct hash table H2 which is for pruning in phase 2 and the hash tree Ck, which is for counting supports of the candidate frequent itemsets in all phases. The results showed that the performance improvement due to the proposed hashing mechanism was 82.2% on the maximum and 18.5% on the average compared to the conventional method using a simple mod operation. Apriori 알고리즘에 기반한 연관 규칙 탐사 알고리즘들은 후보 빈발 항목 집합의 계수 관리를 위한 자료구조로 해시 트리를 사용하고, 많은 시간이 그 해시 트리를 검색하기 위해 소요된다. DHP 연관 규칙 탐사 알고리즘은 해시 트리에 대한 검색 시간을 절약하기 위해 검색 대상인 후보 빈발 항목 집합의 개수를 최대한 줄이고자 노력한다. 이를 위해 사전에 예비 후보 빈발 항목 집합에 대한 간편 계수를 실시한다. 이 때, 예비 계수에 필요한 계산 부담을 줄이기 위해 아주 간단한 직접 해시 테이블 사용을 권고한다. 이 논문에서는 DHP 연관 규칙 탐사 알고리즘의 단계 2에서 사전 전지를 위해 사용되는 직접 해시 테이블 H2와 모든 단계에서 후보 빈발 항목 집합의 계수를 위해 사용되는 해시 트리 Ck에 적용될 수 있는 효율적인 해싱 메카니즘을 제안하고 검증한다. 검증 결과 일반적인 단순 제산(mod) 연산 방법을 사용했을 때보다 제안 방법을 적용했을 경우 최대 82.2%, 평균 18.5%의 성능 향상이 얻어지는 것으로 나타났다.

SpO₂ 기반 휴대형 생체 신호 모니터링 시스템 개발

이형봉,박성욱,정태윤,Lee, Hyung-Bong,Park, Sung-Wook,Chung, Tae-Yun 대한임베디드공학회 2013 대한임베디드공학회논문지 Vol.8 No.5

The traditional medical equipments are devices used by medical professionals but not used in public environment. Common people, however, require light-weight medical devices to make healthcare for themselves nowadays. Those medical devices are used to monitor personal health status such as blood pulse, blood pressure, diabetes. Also, some of them are operated in mobile environment called u-healthcare. This paper implements a portable healthcare system composed of $SpO_2$(Saturation of Partial Pressure Oxygen) sensors and a gateway for detecting hypoxemia during people's leasure activity such as climbing or hiking. The $SpO_2$ sensor is designed as watch style to support dynamic exercise and the gateway is designed as necklace style to support the elderly. The result of a performance evaluation shows that the performance of the $SpO_2$ sensor using reflection technology is not lower than that of a clairvoyant styled $SpO_2$ sensor.

POSIX스레드에 의한 재귀적 알고리즘의 병렬화에서 병렬성 제어 방안

이형봉,백청호 한국정보처리학회 2002 정보처리학회논문지. 컴퓨터 및 통신시스템 Vol.9 No.2

플래시 디스크 기반 행렬전치 알고리즘 심층 분석 및 성능개선

이형봉,정태윤 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.6

The scope of the matrix application is so broad that it can not be limited. A typical matrix application area in computer science is image processing. Particularly, radar scanning equipment implemented on a small embedded system requires real-time matrix transposition for image processing, and since its memory size is small, a general matrix transposition algorithm can not be applied. In this case, matrix transposition must be done in disk space, such as flash disk, using a limited memory buffer. In this paper, we analyze and improve a recently published flash disk-based matrix transposition algorithm named as asymmetric sub-matrix transposition algorithm. The performance analysis shows that the asymmetric sub-matrix transposition algorithm has lower performance than the conventional sub-matrix transposition algorithm, but the improved asymmetric sub-matrix transposition algorithm is superior to the sub-matrix transposition algorithm in 13 of the 16 experimental data.