확률적인 시간 제약 조건을 갖는 실시간 시스템을 위한 과실행 제어 및 합성 기법

김강희(Kanghee Kim),황호영(Hoyoung Hwang) 한국정보과학회 2005 정보과학회논문지 : 시스템 및 이론 Vol.32 No.5·6

Soft real-time applications such as multimedia feature highly variable processor requirements and probabilistic guarantees on deadline misses, meaning that each task in the application meets its deadline with a given probability. Thus, for such soft real-time applications, a system designer may want to improve the system utilization by allocating to each task a processor time less than its worst-case requirement, as long as the imposed probabilistic timing constraint is met. In this case, however, we have to address how to schedule jobs of a task that require more than (or, overrun) the allocated processor time to the task. In this paper, to address the overrun problem, we propose an overrun control method, which probabilistically controls the execution of overrunning jobs. The proposed overrun control method probabilistically allows overrunning jobs to complete for better system utilization, and also probabilistically prevents the overrunning jobs from completing so that the required probabilistic timing constraint for each task can be met. In the paper, we show that the proposed method outperforms previous methods proposed in the literature in terms of the overall deadline miss ratio, and that it is possible to synthesize the scheduling parameters of our method so that all tasks can meet the given probabilistic timing constraints. 멀티미디어와 같은 연성 실시간 응용들은 서비스 품질을 위해 각 태스크들이 마감시간 전에 실행을 마칠 수 있다는 확률적 보장을 요구한다. 시스템 설계자는 태스크들의 확률적 시간 제약 조건을 만족시키는 범위내에서 각 태스크에게 최악 처리기 요구량보다는 적은 처리기 시간을 할당함으로써 시스템 이용률 향상을 추구할 수 있다. 그러나 각 태스크에게 주어진 처리기 할당량이 최악 요구량보다 적은 경우에는 필연적으로 할당량을 초과하는 요구량을 가진 태스크 작업들, 즉 과실행 작업들이 발생하게 되므로 과실행 작업에 대한 제어 기법이 필요하다. 본 논문에서는 연성 실시간 시스템에서의 확률적인 과실행 제어 기법 및 합성 기법을 제안한다. 제안하는 기법은 우선순위 스케줄링의 기반 위에서 각 태스크가 주어진 확률적 시간 제약 조건을 만족할 수 있도록 과실행을 억제함과 동시에, 태스크 실행시간의 가변성으로 인한 여분의 처리기 시간을 일부 과실행 태스크에 유연하게 할당함으로써 시스템 이용률을 향상시킬 수 있다. 본 논문에서는 시스템 모델의 제시와 실험 결과의 분석을 통하여 제안하는 과실행 제어 기법이 마감시간 위반율 측면에서 기존의 기법들보다 우수함을 보이며, 또한 임의의 확률적 시간 제약 조건이 주어질 때 이를 만족시키는 과실행 제어 기법의 매개 변수들을 합성할 수 있음을 보인다.

험로 승차감 향상을 위한 HCS 최적화 방안 연구

김강희(KangHee Kim),김종엽(JongYup Kim),최종명(JongMyung Choi),백광덕(KwangDuk Baek) 한국자동차공학회 2022 한국자동차공학회 부문종합 학술대회 Vol.2022 No.6

As customers demand for comfort increases, performance tuning technology is gradually developing. This is illustrated by the luxurious specifications of shock absorbers or improved performance through careful tuning. This paper aims to demonstrate a technology that can satisfy customers demands for rough ride comfort and control the body of a vehicle. It is named HCS (Hydraulic Compression Stop) and functions similar to the HRS (Hydraulic Rebound Stopper) as we know it, but HCS has the advantage of being able to tune unlikely HRS. This paper shows how the HCS is structured, what characteristics it exhibits, and how it affects vehicle performance. I will share the evaluation results of sample and vehicles and discuss how to use HCS in the future.

한국피아노교수법학회논문집 : 대한민국 피아노 교수법 전공 교과과정 심층연구

김강희 ( Kanghee Kim ) 한국피아노교수법학회 2008 음악교수법연구 Vol.4 No.-

The piano study in the Republic of Korea had been started at the university since March, 1925 at Ewha School (the former Ewha Womans University). The most of piano majors has devoted to teach students privately at the studio or schools. The scholars studied abroad also has taught piano privately. Therefore, a desire for the piano pedagogy program was increased in the Republic of Korea. There are 8 master``s degree programs and 2 doctoral degree programs of piano pedagogy majors in the Republic of Korea from march, 1999. The purpose of this study is to examine those programs in the Republic of Korea and to adapt within the structure of any institution currently offering piano pedagogy. After the review of the American pedagogy curricula of master``s and doctoral degree program through the guideline from the NASM and NCKP handbook, a type of graduate school, a number of students, time for offering classes, admission to graduate study, completion of degree program, credits, curricular structure, general examination, other requirement for the degree completion of pedagogy curricula of the Republic of Korea are analyzed. Since the non-music majors are admitted to the master``s program, preliminary classes in functional keyboard skills, music history and music theory are required and obeyed strictly for the competencies of the master``s degree. More teaching and observation assignments in several ways and full-time faculties are needed. For the doctoral program, more specialized course contents such as research on history of piano pedagogy and discussions on selected readings, business aspects of the independent studio, and so on are needed to develope.

모바일 플랫폼을 위한 네트워크 환경 측정 시스템 설계 및 구현

김강희(Kanghee Kim),여진주(Jinjoo Yeo),김진혁(JinHyuk Kim),최상방(SangBang Choi) 대한전자공학회 2013 전자공학회논문지 Vol.50 No.2

모바일 네트워크 사용량이 급증함에 따라 트래픽 수요 문제를 해결하기 위한 많은 연구가 이뤄지고 있다. 특히 네트워크 환경 측정 분야는 정확한 분석을 통해 네트워크상에 발생되는 문제들의 원인을 찾아냄으로써 트래픽 수요 문제를 해결할 수 있는 기반을 제공한다. 특히 최근 스마트폰의 수요가 늘어남에 따라 모바일 플랫폼 특성이 네트워크에 미치는 영향을 고려한 측정시스템이 필요하다. 이에 본 논문에서는 모바일 플랫폼을 위한 네트워크 환경 측정 시스템을 설계하였다. 설계된 시스템은 클라이언트를 통하여 얻은 패킷의 정보를 통하여 패킷 전송간의 지연시간과 throughput을 실시간으로 계산한다. 그리고 측정시 클라이언트인 모바일 단말기에 요구되는 계산량을 줄임으로써 모바일 단말기에 걸리는 부하를 최소화하였다. 설계한 시스템을 통하여 네트워크 자원을 최대로 사용하였을 시 Wi-Fi 망이 3G 망보다 짧은 전송지연시간, 높은 최대 throughput, 낮은 손실률을 가지고, Android가 iOS보다 짧은 전송지연시간과 높은 최대 throughput을 가지며, UDP가 TCP보다 긴 전송지연시간, 높은 최대 throughput을 가진다는 것을 확인하였다. As a rapid increase of mobile network usage, many studies on solution for network traffic’s demand problem have been done. Especially network environment measurement area provides basis for solving network traffic’s demand problem by finding causes of problems through accurate network analysis. However, as increase of demand for smartphone, we should consider effects of mobile platform’s property measuring mobile network. In this paper, we design a network traffic measurement system considering mobile platform. Through the information from packets, this system calculates packet transmission delay and throughput. We minimize computation cost required for a mobile device that is a client in this system. When fully using network resources, we found that Wi-Fi has shorter transmission delay, higher maximum throughput and lower loss rate than 3G, Android has shorter transmission delay and higher maximum throughput than iOS, and UDP has longer transmission delay and higher maximum throughput through this system.

다양한 최신 워크로드에 적용 가능한 하드웨어 데이터 프리페처 구현

김강희(KangHee Kim),박태신(TaeShin Park),송경환(KyungHwan Song),윤동성(DongSung Yoon),최상방(SangBang Choi) 대한전자공학회 2016 전자공학회논문지 Vol.53 No.12

프리페칭은 프로세서와 메모리 간의 성능 격차를 해소하기 위한 방법 중 하나로 프로세서가 메모리 블록을 요청하기 이전에 미리 캐시에 가져와 메모리 지연을 숨긴다. AMPM 프리페처는 전체 메모리 영역에 대한 접근 패턴을 추적하여 프리페치에 이용하므로 정확도는 우수하나 메모리 접근 패턴을 기록하기 위해 많은 저장 공간이 요구된다. 오프셋 프리페처는 학습을 통해 가장 우수한 오프셋을 선정하고 이를 접근 주소에 더하여 프리페치를 요청한다. 그러나 메모리 접근 패턴이 불규칙할 경우 공격적인 프리페치로 인해 극심한 성능 저하를 겪을 수 있기 때문에 프리페치를 제어하기 위한 기법을 추가로 요구한다. 본 논문에서는 기본적으로 AMPM 프리페처를 사용하고 워크로드의 메모리 접근 패턴에 따라 오프셋 프리페처를 추가로 사용하는 프리페처를 제안한다. 오프셋 프리페처의 정확도가 높은 경우 오프셋 프리페처를 이용함으로써 프리페치에 의한 성능 향상을 최대화하며, 오프셋 프리페처의 정확도가 낮은 경우 오프셋 프리페치를 차단하여 프리페처 성능 저하를 최소화한다. 또한 오프셋 프리페처의 학습 정보를 이용하여 동적으로 MSHR 임계값을 설정함으로써 프로세서의 요구 요청 처리가 프리페치에 의해 지연되지 않도록 한다. Prefetching is one of the method for mitigating performance gab between processor and memory, and it hides memory latency by bringing memory block into cache in advance before processor requests that block. AMPM prefetcher makes use of tracking information of whole memory space for prefetch. So prefetch accuracy is high enough, but it requires a lot of storage for recording memory access pattern. Offset prefetcher requests prefetch to add an access address to a best offset which is elected by training. However, when memory access pattern is dynamic, additional method is required to control prefetch because aggressive prefetches can extremely degrade performance. In this paper, we propose a prefetcher that mainly employs AMPM prefetcher and additionally uses offset prefetcher depending on memory access pattern of workload. If the accuracy of offset prefetcher is high enough, then we can maximize performance improvement using offset prefetcher, and vice versa, we can minimize performance degradation to block offset prefetches. Additionally, as adaptively setting MSHR threshold using training information of offset prefetcher, processing demand requests are not delayed by prefetches.

자이트론 - 자율주행 로봇 개발 기업

김강희(Kanghee Kim),주용수(Yongsoo Joo) 한국정보과학회 2019 정보과학회지 Vol.37 No.9

항공관제용 현시시스템을 위한 패턴매칭 기반의 ASTERIX 파싱 모듈 설계 및 구현

김강희(Kanghee Kim),김호중(Hojoong Kim),은윤동(Yin Run Dong),최상방(SangBang Choi) 대한전자공학회 2014 전자공학회논문지 Vol.51 No.3

최근 국내 항공교통량이 급증함에 따라 안전하고 효율적인 항공교통관리를 위한 항공관제 시스템의 필요성이 커지고 있다. 특히 원활한 항공교통관제를 위해 비행정보구역(FIR : Flight Information Region) 내의 모든 항공상황을 추가지연 없이 보여 주어야 하는 현시시스템의 성능 보장이 무엇보다 중요하다. 본 논문에서는 표준 레이더 감시자료 포맷인 ASTERIX(All purpose STructured Eurocontrol suRveillance Information eXchange) 메시지의 파싱 과정에서 발생하는 오버헤드를 줄여 시스템 부하를 최소화함으로써 안정적인 관제운영을 도모할 수 있는 패턴매칭 기반의 ASTERIX 파싱 모듈을 설계하였다. 설계한 패턴매칭 기반의 ASTERIX 파싱 모듈은 수신 ASTERIX 데이터를 분석하여 패턴을 생성하며, 이후 수신되는 ASTERIX는 패턴을 통해 정의된 프로시저로 파싱한다. 기존 비트 수준 파싱 모듈의 불필요한 파싱 과정을 줄여 현시에 필요한 정보만을 빠르게 추출함으로써 현시 오류를 최소화하고 안정적인 항공관제를 가능하게 한다. 설계한 패턴매칭 기반의 ASTERIX 파싱 모듈의 성능을 비교하기 위하여 일반적인 비트 수준 ASTERIX 파싱 모듈과 비교한 결과, 짧은 처리지연시간, 높은 처리량, 낮은 CPU 사용률을 보이는 것을 확인하였다. Recently, as domestic air traffic dramatically increases, the need of ATC(air traffic control) systems has grown for safe and efficient ATM(air traffic management). Especially, for smooth ATC, it is far more important that performance of display system which should show all air traffic situation in FIR(Flight Information Region) without additional latency is guaranteed. In this paper, we design a ASTERIX(All purpose STructured Eurocontrol suRveillance Information eXchange) parsing module to promote stable ATC by minimizing system loads, which is connected with reducing overheads arisen when we parse ASTERIX message. Our ASTERIX parsing module based on pattern matching creates patterns by analyzing received ASTERIX data, and handles following received ASTERIX data using pre-defined procedure through patterns. This module minimizes display errors by rapidly extracting only necessary information for display different from existing parsing module containing unnecessary parsing procedure. Therefore, this designed module is to enable controllers to operate stable ATC. The comparison with existing general bit level ASTERIX parsing module shows that ASTERIX parsing module based on pattern matching has shorter processing delay, higher throughput, and lower CPU usage.

헤지 문법 항목으로서의 ‘-고요’, ‘-거든요’, ‘-는데요’ 연구

김강희(Kanghee Kim) 한국중원언어학회 2017 언어학연구 Vol.0 No.44

The purpose of this study is to show that Korean final endings “-goyo”, “-geodunyo”, and “-nundaeyo” have a hedging function, and these endings are frequently used in public hearing discourses. Originally, these final endings are the grammaticalized forms of connective endings “-go”, “-geodun”, and “-nundae”. However, this study did not focus on the grammaticalization process instead this study focused on the discourse function of these final endings as a hedge expression. This study applies Hyland (1996)’s theory. According to the analysis of public hearing corpus data, “-goyo” and “-geodunyo” are mostly used as a content-oriented hedge, while “-nundaeyo” is used as an listener-oriented hedge. In other words, “-goyo” and “-geodunyo” are hedge expressions that are used to protect the truth of the proposition, whereas “-nundaeyo” is a hedge expression that is used to promote interactions with the listeners. The consequence of this study is significant, as it contributes further shaping the hedge expressions in Korean. Further study is needed to build a more sophisticated theoretical framework for the Korean hedge expressions.

중급과정의 피아노 교육에 관한 연구

김강희 ( Kanghee Kim ) 한국피아노교수법학회 2005 음악교수법연구 Vol.1 No.-

Piano study, an essential extracurricular activity to Korean children, is a basic for music education in Korea. Even with its popularity. There is an urgent need for developing educational theory including definition and requirements of levels, roles of teachers and attitude of students. In addition, we need to develop various repertoire for the intermediate level and widen musical experiments. Therefore, the writer tries to initiate the establishment of the music educational theory of the intermediate level in Korea. To do so, the writer investigates specialized books in piano pedagogy field and methods by publishing companies through the inside and outside of the country. The writer defines the intermediate level and analyzes intermediate methods. Moreover, the problems, goals of piano lessons, roles and ability of piano teachers, and selection of Intermediate repertoire are examined. Future study areas are as follows: 1) more research on the intermediate repertoire; 2) grade the intermediate repertoire; 3) develop textbooks for the piano pedagogy that are suited for Korean situations; and 4) develop systematic teaching guide.

한국피아노교수법학회논문집 : 베토벤 피아노 소나타 No. 31, Op. 110 Ab Major의 연구

김강희 ( Kanghee Kim ) 한국피아노교수법학회 2007 음악교수법연구 Vol.3 No.-

The great composer Ludwig van Beethoven composed piano sonatas as a pianist. The piano sonata No.31, Op.110 Ab major is the only major work with no dedication. It is the most continuous work of all his piano sonatas. He manipulated tonal areas through this piano sonata No.31, Op.110 Ab major. This sonata is an incredible work of art in the respects of the range of musical style and embracing emotion, the range and expressive effectiveness. The motivic relationships of this sonata are extraordinary. Beethoven compared the texture between fugue and homophony. Beethoven borrowed two Austrian songs such as "Our cat``s had kittens" and "I``m a wretch, you``re a wretch" to the second movement of this sonata. He also used Recitativo in manner of Baroque style with poignant and intense mood. Tempo has changed 7 times and Bebung effect of clavierchord was used. Beethoven alsoborrowed "Es ist volbracht", No. 58 from J. S. Bach`` St. John Passion. The moment of deepest despair and Christ``s final words from the cross are described. In tonic major, the first Fugue is started and climax on V7/I. After the second Arioso, the second Fugue is played in reverse form and ending in a huge affirmation of Ab Major with ff. The tonal areas of whole sonata is Ab major. Beethoven emphasized the Db Major as IV. In the exposition, there is an emphasis on I and IV chords in both key areas. These chords are stressed several times with the third on the top. The notes of Db and D, Fb and F are conflicted in several times to describe the struggling life of human being. The penultimate harmony of the first movement is crucial and represented the clash between F and Fb. The first fugue is seemed the resolution of the tonality. The first fugue was divided into three sub-sections. The second Arioso is shown in the new key of g minor. After the final chord is altered to be G major, the second Fugue has shown in logical manner. Through the tonal ambiguity of tonal area, the harmony is embraced to reenforce the tonic. The motive of the first theme of the first movement is appeared through the whole sonata. The downward motion of third is sequenced several times. The fugue subject is derived from the first theme of the first movement. It omits the opening melody note C. Beethoven wrote this sonata as a drama through the fugue and homophony. The function of the fugue is not only a contrapuntal working out of the subject, but to return to the homophonic texture of the recapitulation of the first movement. After the hopeless first Arioso, the reversed fugue subject has stated. Beethoven manipulated the subject in manner of the augmentation and diminution. Finally, Beethoven glorified the God through the arpeggio of 5 octaves with ff.