• 정보과학회 논문지
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• 제43권6호
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• pp.627-635
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• 2016

로그 구조 파일 시스템에서는 쓰기 작업을 처리할 때 새로운 블록들이 순차적으로 할당된다. 그러나, 다수의 프로세스가 번갈아가며 동기적 쓰기 작업을 요청할 경우, 파일 시스템 상에서는 각 프로세스가 생성한 파일이 단편화될 수 있다. 이 파일 단편화는 읽기 요청을 처리할 때 다수의 블록 I/O를 발생시키기 때문에 읽기 성능을 저하시킨다. 게다가, 미리 읽기 기능은 한 번에 요청되는 데이터의 양을 증가시킴으로써 성능 저하를 더욱 심화시킨다. 이에, 본 논문에서는 파일 단편화 문제를 해결하기 위해 로그구조 파일 시스템의 새로운 클리닝 기법을 제안한다. 제안 기법은 로그 구조 파일 시스템의 클리닝 과정 중 유효 데이터 블록을 아이노드 번호 순으로 정렬함으로써 한 파일의 데이터 블록들을 인접하게 재배치한다. 실험 결과, 제안한 클리닝 기법이 클리닝 전에 비해 약 60%의 파일 단편화를 제거하였고, 그 결과로 미리 읽기 기능을 적용했을 때 읽기 성능을 최고 21%까지 향상시키는 것을 확인하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 2부
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• pp.77-79
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• 2011

As residents and building owners demand maintenance that is required to achieve sustainable building performance, efficient building management methods are required. Even though the demand for maintenance systems is increasing, current maintenance work for high-rise buildings mostly uses conventional ropes and gondolas that pose a high risk of accidents and exhibit poor performance and efficiency. Thus, there is an urgent need to develop an automation robot system that can reduce accidents and improve the maintenance efficiency of the conventional high-rise building façade maintenance system. As a preceding work for the development of an automation robot system, this study classified and analyzed the work processes of actual construction sites and proposed basic techniques for the work mechanisms of the robot system by investigating the motions of cleaning workers.

• 한국의류학회지
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• 제20권6호
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• pp.1048-1061
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• 1996

The most important practical feature that represents the performance of a washing machine is its ability to remove stains or soils from clothes. There are various tests to measure a washing machine's ability to remove stains or soils from clothes. The results of these tests are dependent upon the kind of soiled fabrics used. Moreover, these results may reflect some aspects of the effectiveness of a washing machine in cleaning clothes due to the paritcular compositions of chemicals which comprise soils in soiled fabrics and the particular conditions in which the results are evaluated. After selecting factors presumed to have a major effect on the cleaning ability of a washing machine and choosing most widely used soiled fabrics, we use experimetal statistics methods to screen real factors from them that influence the cleaning ability of a washing machine in a statistically significant manner for each soiled fabric. Using the least number of experimental rules required to extract the necessary information, we then proceed to present the study on the relations between the sets of selected factors and the soiled fabrics. We would then suggest which soiled fabrics is the best for evaluating the performance in cleaning clothes of a washing machine based on the above study.

• Journal of Biosystems Engineering
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• 제33권4호
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• pp.230-238
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• 2008

Mechanization such as machine harvesting, precleaning, drying and cleaning for rapeseed harvested with high moisture content should be accomplished for biodiesel production. In addition, machine drying and cleaning is inevitable in the mechanization of work, just because rice should be transplanted right after harvesting rapeseed in Korea. Particularly, early harvested rapeseed with the combine have high moisture content and undesirable materials such as stalks and stones which make drying-process difficult and lower the efficiency of drying. Therefore, this study was conducted to develop precleaner and cleaner which could remove foreign substances from harvested rapeseeds. The precleaner consists of throw-in hopper, conveyor, feeding hopper, two precleaning sieves and discharging sections. Precleaning capacity was 1,505 kg/hr in shaking frequency of 370 cpm (cycles per minute) and tilt angles of between $5^{\circ}$ and $7^{\circ}$. The efficiency of precleaning was between 90.9% and 91.5%. The cleaner consists of feeding, shaking, blowing, cleaning and discharging sections. Cleaning performance was 435.4kg/hr in the number of rocking motions of 475 cpm and tilt angle of $10^{\circ}$. The ratios of cleaning, foreign substances and loss were 96.5%, 3.5% and 0.2%, respectively.

• 한국컴퓨터정보학회논문지
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• 제13권3호
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• pp.85-90
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• 2008

본 논문에서는 가장 덜 복잡한 공간부터 청소하는 공간 효율적인 새로운 로봇 청소 알고리즘인 SetClean 알고리즘을 제안한다. 청소 완료 시간이 길어지거나, 예측하기 어려운 경우에는 전체 청소 완료시간을 최적화하기보다는 가능한 빠른 시간에 가장 넓은 공간을 최대한 청소하는 것이 유리한 경우가 있다. 이를 위해 SetClean 알고리즘에서는 전체 공간을 셋 커버 알고리즘을 이용하여 청소 가능한 공간으로 구분하고, 단위 시간 당 청소 효율이 가장 높은 공간부터 청소를 진행하게 된다. SetClean 알고리즘은 해당 청소 가능 구역의 면적뿐만 아니라 로봇의 현재위치로부터 해당 청소 구역까지의 이동 거리, 청소 구역 내에서의 로봇의 회전으로 인한 지연 시간 등을 고려하여 최적의 청소 순서를 결정한다. 실험을 통해 SetClean 알고리즘의 동작 과정 및 성능을 보여준다.

• Membrane and Water Treatment
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• 제5권3호
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• pp.207-219
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• 2014

Fouling is one of the critical factors associated with the application of membrane technology in treating palm oil mill effluent (POME), due to the presence of high concentration of solid organic matter, oil, and grease. In order to overcome this, chemical cleaning is needed to enhance the effectiveness of membranes for filtration. The potential use of sodium hydroxide (NaOH), sodium chloride (NaCl), hydrochloric acid (HCl), ethylenediaminetetraacetic acid (EDTA), and ultrapure water (UPW) as cleaning agents have been investigated in this study. It was found that sodium hydroxide is the most powerful cleaning agent, the optimum conditions that apply are as follows: 3% for the concentration of NaOH, $45^{\circ}C$ for temperature solution, 5 bar operating pressure, and solution pH 11.64. Overall, flux recovery reached 99.5%. SEM images demonstrated that the membrane surface after cleaning demonstrated similar performance to fresh membranes. This is indicative of the fact that NaOH solution is capable of removing almost all of the foulants from PES membranes.

• 한국분말재료학회지
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• 제28권1호
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• pp.25-30
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• 2021

The surface of silicon dummy wafers is contaminated with metallic impurities owing to the reaction with and adhesion of chemicals during the oxidation process. These metallic impurities negatively affect the device performance, reliability, and yield. To solve this problem, a wafer-cleaning process that removes metallic impurities is essential. RCA (Radio Corporation of America) cleaning is commonly used, but there are problems such as increased surface roughness and formation of metal hydroxides. Herein, we attempt to use a chelating agent (EDTA) to reduce the surface roughness, improve the stability of cleaning solutions, and prevent the re-adsorption of impurities. The bonding between the cleaning solution and metal powder is analyzed by referring to the Pourbaix diagram. The changes in the ionic conductivity, H2O2 decomposition behavior, and degree of dissolution are checked with a conductivity meter, and the changes in the absorbance and particle size before and after the reaction are confirmed by ultraviolet-visible spectroscopy (UV-vis) and dynamic light scattering (DLS) analyses. Thus, the addition of a chelating agent prevents the decomposition of H2O2 and improves the life of the silicon wafer cleaning solution, allowing it to react smoothly with metallic impurities.

• 한국정밀공학회지
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• 제29권1호
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• pp.56-63
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• 2012

Due to the development of construction technology, there is a considerable increase in the number of skyscrapers in the world. Accordingly, there are rapid growing requests about maintenance systems such as cleaning, painting, and monitoring the processes of facade in highrise buildings. However, it is extremely dangerous working the walls of high-rise buildings, and crashes from buildings have accounted for large proportion of constructional accidents. An alternative solution must be developed with the commercialization of automatic robot systems. For the last decade, interest in developing robots for cleaning and maintenance in facade of highrise buildings has continuously increased. The use of automatic robot systems can be expected to reduce accidents and decrease labor costs. In this paper, we propose a new kind of cleaning mechanism. We have designed and manufactured various cleaning tools for different types of facades with economic commercialization. The cleaning cycle, size, and intensity will be determined by economic constraints as well. The final goals are to design and manufacture tools and robots that can clean facades efficiently and rapidly even in dangerous places. The cleaning tool systems consist of nozzles, brush rollers, and squeezing devices. Furthermore, these tools and robots perform each process utilizing the systems of built-in guide types and gondola types for building maintenance. The performance of the proposed cleaning tools is evaluated experimentally; however additional study should be necessary for safer and more stable commercialization.

• 시멘트 심포지엄
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• 30호
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• pp.182-186
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• 2003

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제15권12호
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• pp.963-967
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• 2009

LFS(Log-structured File System)는 쓰기 요청을 세그먼트 버퍼에 모으고, 세그먼트 단위로 순차 기록함으로써 무작위 쓰기에서도 최적의 성능을 보여준다. 그러나 디스크의 공간이 유한하여, LFS는 여유 세그먼트를 생성하는 클리닝을 수행해야 한다. 파일 시스템의 사용률이 증가함에 따라 세그먼트 클리닝 비용이 급격히 증가하는 단점이 있다. 본 논문에서는 LPS의 쓰기 성능 최적화를 위한 세그먼트 공간 재활용 기법을 설명한다. 이 기법은 유효 세그먼트를 재활용하여 여유 공간을 생성하는 방법으로 빈 세그먼트가 없이 쓰기요청을 처리 할 수 있다. 따라서 높은 비용의 클리닝 동작 없이, 데이터를 세그먼트 내 여유공간에 동적 재배치하여 쓰기요청을 처리한다. 또한 효율적인 세그먼트 공간 재활용을 위해 데이터 및 세그먼트의 지역성을 고려하는 분류기법을 설명한다. 실험 결과에서 이 기법은 파일 시스템의 사용률이 90%인 경우에도 기존 WOLF 기법을 사용한 LFS 보다 HDD에서 1.9배, SSD에서 1.6배의 성능향상을 보여준다.