• 한국컴퓨터정보학회논문지
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• 제24권9호
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• pp.1-8
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• 2019

In this paper, we propose a performance isolation of shared space for virtualized SSD based storage systems, to solve the weakness in a VSSD framework. The proposed scheme adopts a CFQ scheduler and a shared space-based FTL for the fairness and the performance isolation for multiple users on virtualized SSD based storage systems. Using the CFQ scheduler, we ensure SLOs for the storage systems such as a service time, a allocated space, and a IO latency for users on the virtualized storage systems. In addition, to improve a throughput and reduce a computational latency for garbage collection, a shared space-based FTL is adopted to maintain the information of SLOs for users and it manages shared spaces among the users. In our experiments, the proposal improved the throughput of garbage collection by 7.11%, on average, and reduced the computational latency for garbage collection by 9.63% on average, compared to the previous work.

• Journal of Genetic Medicine
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• 제11권2호
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• pp.86-90
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• 2014

Smith-Lemli-Opitz syndrome (SLOS) is a rare autosomal recessive disorder caused by 7-dehydrocholesterol reductase deficiency. The characteristic clinical features are syndactyly of the second and third toes, facial dysmorphism, multiple malformations, and intellectual disability. Few cases of SLOS have been reported in Korea. We observed a male patient with SLOS who presented with typical facial features, undescended testes, microcephaly, bilateral syndactyly of the second and third toes, and cardiac defects, including patent ductus arteriosus and atrial septal defect. Mutation analysis of the DHCR7 gene identified compound heterozygous mutations of c.907G>A (p.Gly303Arg) and c.1055G>A (p.Arg352Gln). In a review of the literature, c.1054C>T (p.Arg352Trp) was the most common mutation reported in Far East Asian countries. This report describes the clinical features, biochemical data, molecular characteristics, and clinical outcome of a Korean patient with SLOS.

• Clinical and Experimental Pediatrics
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• 제51권11호
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• pp.1236-1240
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• 2008

Smith-Lemli-Opitz 증후군은 콜레스테롤 합성 과정의 장애로 발생하는 상염색체 열성으로 유전되는 드문 질환으로 다양한 기형을 동반한다. 이는 DHCR7 유전자 변이로 인한 활성도 저하로 발생하는 질환으로 7DHC, 8DHC의 증가 및 체내 콜레스테롤의 감소에 따른 임상상을 특징으로 한다. 저자들은 국내에서 최초로 SLO 증후군을 유전자 분석을 통하여 진단하였기에 이를 문헌 고찰과 함께 보고하는 바이다.

• 대한유전성대사질환학회지
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• 제14권1호
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• pp.60-65
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• 2014

스미스-렘리-오피츠 증후군은 상염색체 열성유전질환으로 콜레스테롤 합성의 장애로 나타나는 질병이다. 7-dehydrochlolesterol reductase 유전자의 변이로 인하여 콜레스테롤을 합성하지 못함으로써 정신지체, 자폐증, 발육부진, 내부장기 기형, 손과 발의 기형, 면역기능 저하, 소화기 및 시력의 문제 등이 나타난다. 이 질환은 경미한 증상에서부터 치명적인 증상까지 다양한 스펙트럼을 가진다. 저자들은 다양한 기형을 가진 환아에서 조기에 스미스-렘리-오피츠 증후군을 유전자 분석을 통하여 진단하였으며, 조기 진단 후 식이진행 및 기형에 대한 치료, 콜레스테롤을 보충 하였으며, 이를 문헌고찰과 함께 보고하는 바이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2357-2380
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• 2019

In this paper, we investigate the impact of hardware impairments (HWIs) on the performance of a downlink massive MIMO system. We consider a single-cell system with maximum ratio transmission (MRT) as precoding scheme, and with all the HWIs characteristics such as phase noise, distortion noise, and amplified thermal noise. Based on the system model, we derive closed-form expressions for a typical user data rate under two scenarios: when a common local oscillator (CLO) is used at the base station and when separated oscillators (SLOs) are used. We also derive closed-form expressions for the downlink transmit power required for some desired per-user data rate under each scenario. Compared to the conventional system with ideal transceiver hardware, our results show that impairments of hardware make a finite upper limit on the user's downlink channel capacity; and as the number of base station antennas grows large, it is only the hardware impairments at the users that mainly limit the capacity. Our results also show that SLOs configuration provides higher data rate than CLO at the price of higher power consumption. An approach to minimize the effect of the hardware impairments on the system performance is also proposed in the paper. In our approach, we show that by reducing the cell size, the effect of accumulated phase noise during channel estimation time is minimized and hence the user capacity is increased, and the downlink transmit power is decreased.

• 대한유전성대사질환학회지
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• 제14권1호
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• pp.48-53
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• 2014

Smith-Lemli-Opitz syndrome (SLO) is a rare, autosomal recessive disease caused by an inborn error in cholesterol synthesis. Patients with this disease suffer from multiple malformations due to reduced activity of 7-dehydrocholesterol reductase (DHCR7), which increases 7-dehydrocholesterol (7DHC) and 8-dehydrocholesterol (8DHC) concentrations and decreases cholesterol concentration in body fluids and tissue. Here, we describe Korean siblings with SLO who were diagnosed recently, and performed a review of literature about Korean cases with SLO to date. Microcephaly and syndactyly of the second and third toes are the most common physical finding in SLOS patients. Other malformations including growth failure, cleft palate or bifid uvula, various heart malformation, genital ambiguity in males are also accompanied. Not all patients showed low levels of serum cholesterol, so DHCR7 mutation analysis can be helpful to confirmative diagnosis. Two mutations on p.R352 locus (p.R352W and p.R352Q) are commonly identified in Korean SLO patients. Although rare in Korea, SLO should be considered in the differential diagnosis of growth failure with intellectual disability, especially in patients with multiple congenital anomalies.