• Journal of KIISE:Computer Systems and Theory
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• v.36 no.3
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• pp.171-180
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• 2009

Slowly, but surely, we are seeing the emergence of a variety of embedded systems that are employing Storage Class RAM (SCRAM) such as FeRAM, MRAM and PRAM, SCRAM not only has DRAM-characteristic, that is, random byte-unit access capability, but also Disk-characteristic, that is, non-volatility. In this paper, we propose a new software architecture that allows SCRAM to be used both for main memory and for secondary storage simultaneously- The proposed software architecture has two core modules, one is a SCRAM driver and the other is a SCRAM manager. The SCRAM driver takes care of SCRAM directly and exports low level interfaces required for upper layer software modules including traditional file systems, buddy systems and our SCRAM manager. The SCRAM manager treats file objects and memory objects as a single object and deals with them in a unified way so that they can be interchanged without copy overheads. Experiments conducted on real embedded board with FeRAM have shown that the SCRAM driver indeed supports both the traditional F AT file system and buddy system seamlessly. The results also have revealed that the SCRAM manager makes effective use of both characteristics of SCRAM and performs an order of magnitude better than the traditional file system and buddy system.

• Journal of Aerospace System Engineering
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• v.17 no.2
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• pp.111-119
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• 2023

Internal storage state, weight data, and weight-centered calculation values for overhead bin can all be seen in this paper's real-time internal status identification system. The suggested system offers such valuable data via a range of sensors, including load cells and switch arrays. The proposed system could locate internal free space, locate the center of gravity, and give real-time visual information. It was developed utilizing an embedded system and the C programming language. These features led to the creation of smart overhead bins and real-time cargo loading monitoring technologies, both of which could one day aid in the creation of a cargo loading automation system.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.01a
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• pp.33-36
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• 2012

디지털 컨버젼스 시대가 도래하면서 자원이 제한된 소형기기들의 사용이 비약적으로 증가하는 추세이다. 실시간 운영체제가 탑재되는 임베디드 시스템은 특성상 제한된 메모리를 가지기 때문에 제한된 메모리를 효율적으로 사용할 수 있는 기법이 적용되어야 한다. 이러한 제한된 메모리 관리를 효율적으로 사용하도록 기존의 CNU_RTOS에서는 실시간 운영체제의 메모리 관리 기법인 메모리 풀(Pool)과 힙(Heap) 알고리즘을 사용하였다. 시간 결정성을 보장하기 위해 힙을 할당하는 방법으로 first fit 알고리즘을 사용하였지만 외부 단편화로 인한 메모리 낭비를 감수하게 되었다. 본 논문에서는 힙 스토리지 매니저에서 발생하는 외부 단편화를 최소화하기 위해 버디 시스템을 이용한 메모리 관리 기법을 설계 및 구현하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.709-712
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• 2017

RocksDB는 Facebook에서 LevelDB를 기반으로 개발한 임베디드 key-value 스토리지 엔진이다. Log structured tree(LSM-tree)를 기본구조로 사용하는 RocksDB는 데이터를 레벨단위로 저장한다. 지속적인 데이터 입력으로 인하여 레벨의 크기를 초과하게 되면 하위 레벨의 SST 파일과 병합을 통해 하위레벨로 내려 보낸다. 이 과정에서 디바이스의 부가적인 쓰기가 발생한다. 본 논문에서는 RocksDB의 디스크영역에 있는 SST 파일의 크기가 디바이스의 쓰기 증폭에 미치는 영향을 분석하였다. SST 파일크기변화에 따른 디바이스의 쓰기 증폭과 성능변화를 측정하고 비교하였다. 실험결과를 통해 SST의 크기가 작을수록 쓰기 증폭이 줄었지만 디바이스의 쓰기와 읽기 성능이 감소하는 것을 확인하였다. 결과적으로 쓰기 증폭을 줄이고 성능을 최대화 하기 위해서는 이 둘의 트레이드오프를 파악하고 분석하여 시스템에 맞는 최적의 SST 파일 크기를 찾아야한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05a
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• pp.483-486
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• 2003

실시간 운영체제는 효율성 및 공평성을 중시하는 다른 범용 운영체제와는 달리 논리적 정확성과 시간적 정확성을 보장하기 위해 스케줄링하는 운영체제를 의미한다. 임베디드 시스템에서 동작하는 실시간 운영체제는 제한된 환경에서 제한된 목적으로 사용되고 있다. 특히 메모리는 실시간 운영체제의 실행에 있어서 꼭 필요한 자원이므로 이에 대한 효과적인 관리가 필수적이라 할 수 있다. 본 논문은 동적 메모리 할당을 위한 힙 스토리지 매니저와 메모리 풀을 설계하고 구현한 내용을 기술한다.

• Journal of KIISE:Computer Systems and Theory
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• v.37 no.2
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• pp.90-102
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• 2010

Flash memory has been widely used as an important storage device for consumer electronics. For the flash memory-based storage systems, FTL (Flash Translation Layer) is used to handle the mapping between a logical page address and a physical page address. Especially, log buffer-based FTLs provide a good performance with small-sized mapping information. In designing the log buffer-based FTL, one important factor is to determine the mapping structure between data blocks and log blocks, called associativity. While previous works use static associativity fixed at the design time, we propose a new log block mapping scheme which adjusts associativity based on the run-time workload. Our proposed scheme improves the I/O performance about 5~16% compared to the static scheme by adjusting the associativity to provide the best performance.

• Journal of Internet Computing and Services
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• v.10 no.5
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• pp.195-209
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• 2009

The embedded software has been become more important than the hardware in mobile systems in ubiquitous society. The improvement models such as CMMI(Capability Maturity Model Integration) and SPICE(Software Process Improvement and Capability dEtermination) are used to improve the quality of software in general systems. Software process improvement is also necessary for mobile embedded software development to improve its quality. It is not easy to apply the general software improvement model to the mobile embedded software development due to the high cost effectiveness and heavy process. On the other hand, XP has the characteristics on focused communications with customers and iteration development. It is specially suitable for mobile embedded software development as depending on customer's frequent requirement changes and hardware attributes. In this paper, we propose a framework for development small process improvement based XP(eXtreme Programming)'s practice in order to accomplish CMMI level 2 or 3 in mobile embedded software development at the small organizations. We design and implement the Mobile Embedded Software Process Improvement System(MESPIS) to support process improvement. We also suggest the evaluation method for the mobile embedded software development process improvement framework with CMMI coverage check by comparing other process improvement model. In the future, we need to apply this proposed framework to real project for practical effectiveness and the real cases quantitative. It also include the enhance the functionality of MESPIS.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.5
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• pp.35-40
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• 2010

NAND flash memory has been widely used than traditional HDD in PDA and other mobile devices, embedded systems, PC because of faster access speed, low power consumption, vibration resistance and other benefits. DiskSim and other HDD simulators has been developed that for find improvements for the software or hardware. But there is a few Linux-based simulators for NAND flash memory and SSD. There is necessary for Windows-based NAND flash simulator because storage devices and PC using Windows. This paper describe for development of simulator-NFSim for FTL performance analysis in NAND flash. NFSim is used to measure performance of various FTL algorithms and FTL wear-level. NAND flash memory model and FTL algorithm developed using Windows Driver Model and class for scalability. There is no need for another tools because NFSim using graph tool for data measure of FTL performance.

• The KIPS Transactions:PartA
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• v.15A no.6
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• pp.335-344
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• 2008

We propose an adaptive garbage collection technique for hybrid flash memory which has both SLC and MLC. Since SLC area is fast and MLC area has low cost, the proposed scheme utilizes the SLC area as log buffer and the MLC area as data block. Considering the high write cost of MLC flash, the garbage collection for the SLC log buffer moves a page into the MLC data block only when the page is cold or the page migration invokes a small cost. The other pages are moved within the SLC log buffer. Also it adjusts the parameter values which determine the operation of garbage collection adaptively considering I/O pattern. From the experiments, we can know that the proposed scheme provides better performance compared with the previous flash management schemes for the hybrid flash and finds the parameter values of garbage collection close to the optimal values.