• Title, Summary, Keyword: MLC

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IMRT 위한 MLC QA Device 제작

  • 심재구;주상규;박영환
    • The Journal of Korean Society for Radiation Therapy
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    • v.13 no.1
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    • pp.47-50
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    • 2001
  • Purpose : 체내에서 optimal한 dose distribution을 얻기 위해 도입된 IMRT를 시행할 때 사용하는 MLC는 기계특성상 장기적인 check와 교정을 요한다. 또한 MLC는 static하지 않고 dynamic하기 때문에 leaf position의 실제 위치가 매우 중요하다. MLC QA를 위해 QA 소요시간 및 노력이 많이 MLC position check 요구되는 불편이 있어, 삼성서울 병원에서 필름을 이용한 MLC position check device를 제작하여 간편하게 사용하고 그 우수성에 대해 결과를 보고하고자 한다. Materials and Method : MLC position을 check하기위해 사각형 의 device(acryl:$40{\times}40{\times}5cm$)를 제작하였다. position check device의 정확도를 위해 표면에 real scale 표시용으로 Pb marker를 2cm 간격으로 부착하였다. MLC QA film은 마주보는 (opposite) MLC leaf의 간격이 4mm로 set up한 상태에서 double exposure하여 marker를 이용하여 오차를 분석하였다. MLC position check device의 효율성을 평가하기위해 6MV photon으로 10번 반복 실험을 실시하여 MLC leaf의 평균오차를 조사하고 조사에 걸린 시간을 비교하여 유용성을 평가하였다. Results : 실험결과 MLC leaf의 평균오차를 조사하고 조사에 걸린 시간을 비교하여 유용성을 평가하였다. 범위는 1.45mm였고, 최소 오차는 0.34mm로 나타났다. 1회 조사에 걸린 시간은 평균적으로 약 30분 정도 소요되었다. MLC position check device의 효율성을 평가한 결과오차의 반복성은 관찰되지 않았다. Conclusion : MLC leaf position의 정기적인 check와 교정을 위해 본원에서는 주1회 정기 position error를 check하고 있으며, 평균 월1회 교정을 한다. 본 실험을 통해 MLC position check device를 사용하여 leaf 오차가 2mm이하의 만족할 만한 결과를 얻었다. 또한 MLC position check device를 사용하면 짧은 시간에 모든 leaf의 position error를 쉽게 측정할 수 있고 한 장의 필름으로 모든 결과를 평가할 수 있어 경제성 및 업무의 효율성도 높일 수 있었다.

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Comparison and Evaluation of radiotherapy plans by multi leaf collimator types of Linear accelerator (선형가속기의 다엽콜리메이터 형태에 따른 치료계획 비교 평가)

  • Lim, Ji Hye;Chang, Nam Joon;Seok, Jin Yong;Jung, Yun Ju;Won, Hui Su;Jung, Hae Youn;Choi, Byeong Don
    • The Journal of Korean Society for Radiation Therapy
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    • v.30 no.1_2
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    • pp.129-138
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    • 2018
  • Purpose : An aim of this study was to compare the effect of multi leaf collimator(MLC) types for high dimension radiotherapy in treatment sites used clinically. Material and Method : 70 patients with lung cancer, spine cancer, prostate cancer, whole pelvis, head and neck, breast cancer were included in this study. High definition(HD) MLC of TrueBeam STx (Varian Medical system, Palo Alto, CA) and millenium(M) MLC of VitalBeam (Varian Medical system, Palo Alto, CA) were used. Radiotherapy plans were performed for each patient under same treatment goals with Eclipse (Version 13.7, Varian Palo Alto USA, CA). To compare the indicators of the radiotherapy plans, planning target volume(PTV) coverage, conformity index(CI), homogeneity index(HI), and clinical indicators for each treatment sites in normal tissues were evaluated. To evaluate low dose distribution, $V_{30%}$ values were compared according to MLC types. Additionally, length and volume of targets for each treatment sites were investigated. Result : In stereotatictic body radiotherapy(SBRT) plan for lung, the average value of PTV coverage was reduced by 0.52 % with HD MLC. With SBRT plan using HD MLC for spine, the average value of PTV coverage decreased by 0.63 % and maximum dose decreased by 1.13 %. In the test of CI and HI, the values in SBRT plan with HD MLC for spine were 1.144, 1.079 and the values using M MLC were 1.160, 1.092 in SBRT plan for lung, The dose evaluation of critical organ was reduced by 1.48 % in the ipsilateral lung mean dose with HD MLC. In prostate cancer volumetric modulated arc therapy(VMAT) with HD MLC, the mean dose and the $V_{30}$ of bladder and the mean dose and the $V_{25}$ of rectum were reduced by 0.53 %, 1.42 %, 0.97 %, and 0.69 %, respectively (p<0.05). The average value of heart mean dose was reduced by 0.83 % in breast cancer VMAT with M MLC. Other assessment indices for treatment sites showed no significant difference between treatment plans with two types of MLC. Conclusion : Using HD MLC had a positive impact on the PTV coverage and normal tissue sparing in usually short or small targets such as lung and spine SBRT and prostate VMAT. But, there was no significant difference in targets with long and large such as lung, head and neck, and whole pelvis for VMAT.

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Designing Hybrid HDD using SLC/MLC combined Flash Memory (SLC/MLC 혼합 플래시 메모리를 이용한 하이브리드 하드디스크 설계)

  • Hong, Seong-Cheol;Shin, Dong-Kun
    • Journal of KIISE:Computing Practices and Letters
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    • v.16 no.7
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    • pp.789-793
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    • 2010
  • Recently, flash memory-based non-volatile cache (NVC) is emerging as an effective solution to enhance both I/O performance and energy consumption of storage systems. To get significant performance and energy gains by NVC, it would be better to use multi-level-cell (MLC) flash memories since it can provide a large capacity of NVC with low cost. However, the number of available program/erase cycles of MLC flash memory is smaller than that of single-level-cell (SLC) flash memory limiting the lifespan of NVC. To overcome such a limitation, SLC/MLC combined flash memory is a promising solution for NVC. In this paper, we propose an effective management scheme for heterogeneous SLC and MLC regions of the combined flash memory.

Cooling System Design Factors related to Mechanical Load Component (MLC) in Data Center (데이터센터 냉방 시스템의 MLC(Mechanical Load Component) 관련 설계인자 도출)

  • Kim, Ji-Hye
    • Journal of Korean Institute of Architectural Sustainable Environment and Building Systems
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    • v.12 no.6
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    • pp.606-617
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    • 2018
  • Increased density of racks has resulted in increased use of data center cooling energy and the needs for energy efficient cooling systems has increased. In response to these needs, ASHRAE presented a performance indicator, which is Mechanical Load Component (MLC), for the purpose of evaluating systems at the design stage. However, the MLC metrics presented in the current standard can only be determined for system compliance and compared alternative systems with the system configuration completed. Therefore, there are limitations to considering MLC from the early stages of design. In this study, to extend the scope of application of MLC in the design phase, the design factors of the main equipment comprising the cooling system are classified by the MLC load component and interrelations between design factors were identified.

Fault Test Algorithm for MLC NAND-type Flash Memory (MLC NAND-형 플래시 메모리를 위한 고장검출 테스트 알고리즘)

  • Jang, Gi-Ung;Hwang, Phil-Joo;Chang, Hoon
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.49 no.4
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    • pp.26-33
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    • 2012
  • As the flash memory has increased the market share of data storage in imbedded system and occupied the most of area in a system, It has a profound impact on system reliability. Flash memory is divided NOR/NAND-type according to the cell array structure, and is classified as SLC(Single Level Cell)/MLC(Multi Level Cell) according to reference voltage. Although NAND-type flash memory is slower than NOR-type, but it has large capacity and low cost. Also, By the effect of demanding mobile market, MLC NAND-type is widely adopted for the purpose of the multimedia data storage. Accordingly, Importance of fault detection algorithm is increasing to ensure MLC NAND-type flash memory reliability. There are many researches about the testing algorithm used from traditional RAM to SLC flash memory and it detected a lot of errors. But the case of MLC flash memory, testing for fault detection, there was not much attempt. So, In this paper, Extend SLC NAND-type flash memory fault detection algorithm for testing MLC NAND-type flash memory and try to reduce these differences.

Genomic Organization, Intronic Duplications, and Promoter Characteristics of the Fast Skeletal Myosin Light Chain-2 Gene (mlc2f) from Javanese Ricefish Oryzias javanicus

  • Lee, Sang Yoon;Kim, Dong Soo;Nam, Yoon Kwon
    • Fisheries and aquatic sciences
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    • v.15 no.4
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    • pp.325-335
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    • 2012
  • The present study characterized the fast skeletal myosin light chain-2 gene (mlc2f) in the euryhaline Javanese ricefish (Oryzias javanicus: Beloniformes). Coding nucleotide and deduced amino acid sequences of Javanese ricefish mlc2f were well conserved in the vertebrate lineage. Javanese ricefish mlc2f showed a typical seven-exon structure, and its promoter exhibited transcription factor binding motifs common to most muscle-specific genes. However, Javanese ricefish mlc2f also displayed tandem duplications of intronic sequences in both intron 1 and intron 3. Based on quantitative reverse transcription-polymerase chain reaction, the mlc2f transcripts were highly predominant in skeletal muscles of adults and were differentially modulated during embryonic development. Microinjection of the mlc2f promoter-driven red fluorescent protein (RFP) reporter construct successfully exhibited heterologous expression of the fluorescent reporter, primarily in muscular areas of hatchlings, although the distribution pattern of RFP signals was not uniform due to the mosaic nature of the introduced transgene. Data from this study indicate that the Javanese ricefish mlc2f gene has undergone "intra-intronic" duplication events in a species-specific manner and that the mlc2f regulator may also be useful in heterologous expression assays of the skeletal muscles of this species.

Dead Block-Aware Adaptive Write Scheme for MLC STT-MRAM Caches

  • Hong, Seokin
    • Journal of the Korea Society of Computer and Information
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    • v.25 no.3
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    • pp.1-9
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    • 2020
  • In this paper, we propose an efficient adaptive write scheme that improves the performance of write operation in MLC STT-MRAM caches. The key idea of the proposed scheme is to perform the write operation fast if the target MLC STT-MRAM cells contain a dead block. Even if the fast write operation on the MLC STT-MRAM evicts a cache block from the MLC STT-MRAM cells, its performance impact is low if the evicted block is a dead block which is not used in the future. Through experimental evaluation with a memory simulator, we show that the proposed adaptive write scheme improves the performance of the MLC STT-MRAM caches by 17% on average.

Location-Aware Hybrid SLC/MLC Management for Compressed Phase-Change Memory Systems (압축 기반 상변화 메모리 시스템에서 저장 위치를 고려한 하이브리드 SLC/MLC 관리 기법)

  • Park, Jaehyun;Lee, Hyung Gyu
    • IEMEK Journal of Embedded Systems and Applications
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    • v.11 no.2
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    • pp.107-116
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    • 2016
  • Density of Phase-Change Memory (PCM) devices has been doubled through the employment of multi-level cell (MLC) technology. However, this doubled-capacity comes in the expense of severe performance degradation, as compared to the conventional single-level cell (SLC) PCM. This negative effect on the performance of the MLC PCM detracts from the potential benefits of the MLC PCM. This paper introduces an efficient way of minimizing the performance degradation while maximizing the capacity benefits of the MLC PCM. To this end, we propose a location-aware hybrid management of SLC and MLC in compressed PCM main memory systems. Our trace-driven simulations using real application workloads demonstrate that the proposed technique enhances the performance and energy consumption by 45.1% and 46.5%, respectively, on the average, over the conventional technique that only uses a MLC PCM.

Adaptive Garbage Collection Technique for Hybrid Flash Memory (하이브리드 플래시 메모리를 위한 적응적 가비지 컬렉션 기법)

  • Im, Soo-Jun;Shin, Dong-Kun
    • 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.

The Design of LTCC MLC Bandpass Filters using λ/4 Hair-pin Resonators (λ/4 Hair-pin 공진기를 이용한 LTCC MLC 대역통과 여파기의 설계)

  • 성규제;여동훈
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.1
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    • pp.14-19
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    • 2003
  • In this paper, a λ/4 hair-pin resonator is proposed to reduce the size of resonators. A LTCC MLC bandpass filter is designed using the λ/4 hair-pin resonators. The electromagnetic coupling structure between two planar resonators is analysed. The equivalent circuit is derived to explain the behavior of the LTCC MLC bandpass filter using λ/4 hair-pin resonators. A design procedure is also described. The simulated and measured results of 1.8 GHz band 2-pole bandpass filter are presented.