• 마이크로전자및패키징학회지
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• 제24권4호
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• pp.91-95
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• 2017

Package-On-Package (PoP) technology is developing toward smaller form factors with high-speed data transfer capabilities to cope with high DDR4x memory capacity. The common application processor (AP) used for PoP devices in smartphones has the bottom package as logic and the top package as memory, which requires both thermally and electrically enhanced functions. Therefore, it is imperative that PoP designs consider both thermal and power distribution network (PDN) issues. Stacked packages have poorer thermal dissipation than single packages. Since the bottom package usually has higher power consumption than the top package, the bottom package impacts the thermal budget of the top package (memory). This paper investigates the thermal and electrical characteristics of PoP designs, particularly the bottom package. Findings include that via and dense via-cluster volume have an important role to lower thermal resistance to the motherboard, which can be an effective way to manage chip hot spots and reduce the thermal impact on the memory package. A Cu block and dense via-cluster layout with an optimal location are proposed to drain the heat from the chip hot spots to motherboard which will enhance thermal and electrical performance at the design stage. The analytical thermal results can be used for design guidelines in 3D packaging.

• 한국정밀공학회지
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• 제22권4호
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• pp.194-202
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• 2005

The objective of this paper is to develop a multi-functional hotwire cutting system (MHC) using EPS-foam block or plate as the working material. Because the MHC apparatus employs a four-axis synchronized hotwire cutter with the structure of two XY movable heads and a turntable, it allows the easy fabrication of various 3D shapes, such as (1) an axisymmetric shape or a sweeping cross-sectioned pillar shape using the hot-strip in the form of sweeping surface and EPS foam block on the turntable, (2) a polyhedral complex shape using the hotwire and EPS foam block on the turntable, and (3) a ruled surface approximated freeform shape using the hotwire and EPS foam plate. In order to examine the applicability of the developed MHC apparatus, an axisymmetric shape, a polyhedral shape and a large-sized freeform shape were fabricated on the apparatus.

• 한국화재소방학회논문지
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• 제23권2호
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• pp.1-5
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• 2009

본 연구에서는 분전반의 설치 형태를 조사하였고, 향 검지 시스템의 재현 실험을 통해서 전기 재해 예방의 가능성을 확인하고자 한다. 주택용 분전반 내에 설치된 차단기는 MCCB, RCD 순서로 되어 있으나, 산업용은 혼용되고 있다. 접속이 부적절하게 된 단자대에 가진기를 이용하여 진동을 가했을 때 불꽃이 확인되었다. 단자대에 향 캡슐을 부착하여 실험한 결과, 발생한 열에 의해 캡슐이 정확하게 작동되었다. 센서의 설치 위치에 따라 검지 시간의 차이는 약 10초 이었다. 향 검지 시스템은 전기 설비 사고 예방이 가능한 것으로 판단된다. 전선의 접속부에서 이상 발열이 있을 때 과열의 상태를 관리자에게 경보해 줌으로써 사고 예방이 가능할 것으로 판단된다.

• 대한전자공학회논문지SP
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• 제46권1호
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• pp.49-55
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• 2009

본 논문에서는 임의의 직교 블록 변환 영역에서 직접 영상 크기를 변경하는 기법을 개발한다. 이를 위해, 임의 직교 변환영역에서 영상 크기 변환을 수행하는 모든 과정을 행렬 곱으로 표현하여, 해상도 변환을 수행하는 행렬을 유도한다. 해상도 변환 행렬은 영상 특성에 따라 직교 블록 변환에 알맞은 일반식으로 설계한다. 개발된 기법은 기존의 실수 DCT 영역 뿐만 아니라 H.264/AVC에 적용 가능한 $4{\times}4$ Modified DCT 및 Hadamard 변환과 같은 다양한 직교 변환 영역에 적용할 수 있고, 동영상 부호화 시 사용되는 대표적인 시퀀스 영상들의 해상도 변환에 적용 가능함을 실험을 통하여 검증하였다.

• 한국세라믹학회지
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• 제55권2호
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• pp.116-125
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• 2018

Color shade variation was investigated in zirconia dental blocks, prepared using commercial powders. As a reference color-shade block we used the color indexes of A2, A3.5, A4 and B3, according to the VITA classical color scale. The zirconia powders for color shade blocks showed colors of white, yellow, pink and grey, respectively, after firing at $1530^{\circ}C$. The zirconia powders were mixed according to the recipe of color shade blocks and shaped at lower pressure using a uniaxial hydrostatic press. The shaped sample was inserted into a vinyl pack and sealed in a vacuum form machine. The shaped block samples were reshaped at 450 bar using an isostatic cold press and fired at $1530^{\circ}C$ for three hours. In order to investigate the atmospheric color variation with firing temperature, the A2, A3.5, A4 and B3 sintered blocks were fired between $700^{\circ}C$ and $1300^{\circ}C$ under controlled atmosphere of $pN_2$ and $pO_2$. The surface color picture was taken using a smart phone camera and compared with the results obtained using the VITA classical color scale. Quantitative color index value, CIELAB, was measured using a color-meter. Above $800^{\circ}C$, the color darkness greatly increased with the increase of the reduction temperature and keeping time.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.932-935
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• 2002

In this paper, we introduce new FTL(Flash Translation Layer) driver algorithm that tolerate the power off errors. FTL driver is the software that provide the block device interface to the upper layer software such as file systems or application programs that using the flash memory as a block device interfaced storage. Usually, the flash memory is used as the storage devices of the mobile system due to its low power consumption and small form factor. In mobile system, the state of the power supplement is not stable, because it using the small sized battery that has limited capacity. So, a sudden power off failure can be occurred when we read or write the data on the flash memory. During the write operation, power off failure may introduce the incomplete write operation. Incomplete write operation denotes the inconsistency of the data in flash memory. To provide the stable storage facility with flash memory in mobile system, FTL should provide the fault tolerance against the power off failure. SSR (Simple Sector Remapper) is a fault tolerant FTL driver that provides block device interface and also provides tolerance against power off errors.

• The Korean Journal of Pain
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• 제9권1호
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• pp.98-101
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• 1996

Background: Lumbar epidural steroid injection for relief of low back pain and sciatica has become a popular procedure. further, cervical epidural steroid injection with nerve block (CESNB) is known to be effective for the management of acute and chronic pain of neck, shoulder and arm. However, many anesthesiologists are not familiar with CESNB. Methods: Charts of 34 patients who had undergone 60 cervical epidural steroid injections over a three year period, 1993 to 1995, were reviewed. We studied the followings: initial visit and department, injected interspaces, personal characteristics, indications for injection and complications. Results: Patients' first visits were mainly to orthopaedics (11 patients) and neurosurgery (10 patients). Epidural injection sites were: C7-T1 interspace (29 patients) and C6-C7 interspace (6 patients). Mean age of patients were 50.1 years. range 21~73 years. There were twenty male and fourteen female patients. Complications varied from dizziness after CESNB (1 patient). loss of consciousness with transient apnea (2 patients), and local infection with suspicious meningitis (1 patient). Conclusion: We conclude from the above data that CESNB is a good, safe and conservative form of therapeutic procedure in the management of patients suffering from cervical radiculopathy, and neck and shoulder pain.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권12호
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• pp.6043-6062
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• 2019

Low-rank matrix decomposition has shown its capability in many applications such as image in-painting, de-noising, background reconstruction and defect detection etc. In this paper, we consider the texture background of rail track images and the sparse foreground of the defects to construct a low-rank matrix decomposition model with block sparsity for defect inspection of rail tracks, which jointly minimizes the nuclear norm and the 2-1 norm. Similar to ADM, an alternative method is proposed in this study to solve the optimization problem. After image decomposition, the defect areas in the resulting low-rank image will form dark stripes that horizontally cross the entire image, indicating the preciselocations of the defects. Finally, a two-stage defect extraction method is proposed to locate the defect areas. The experimental results of the two datasets show that our algorithm achieved better performance compared with other methods.

• 한국ITS학회 논문지
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• 제9권1호
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• pp.34-41
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• 2010

본 논문에서는 복조후 전송 (DF: Decode-and-Forward) 중계기를 사용하는 협력통신 (Cooperative Communication) 시스템에서 동일 채널로 전송된 다른 신호에 의해 단말기에 발생할 수 있는 간섭 완화 방법에 대해 분석하고 실험하였다. 간섭완화 방법은 동일 채널로 전송할 신호를 직교 부호를 이용하여 부호화한 후 전송하면, 수신기는 미리 알고 있는 직교 부호를 이용하여 자신이 원하는 신호만 수신하는 것이다. 본 논문에서 이용한 직교 부호는 직교 골드 부호 (Orthogonal Gold Code) 를 이용하였다. 하지만 직교 골드 부호 이외에 직교 성질을 가지는 다른 부호를 직교 부호로 사용할 수 있다. 또한 추가적인 배열 이득으로 인해 시스템 성능을 향상시키기 위해 시공간 블록 부호화 (STBC : Space Time Block Coding) 개념을 적용하였다.

• 한국산업융합학회 논문집
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• 제24권6_2호
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• pp.827-839
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• 2021

Due to climate change and population growth, water scarcity is getting worse all over the world. Among various methods for desalination of seawater, the Multi-Effect Adsorptive Desalination method, which combines the existing Multi-Effect Desalination method and the Adsorptive Desalination method and can produce high-concentration-high-concentration freshwater, is emerging. Because the Multi-Effect Adsorptive Desalination method combines the two different methods, the system becomes complicated and the possibility of failure increases. Therefore, in this study, availability analysis was performed on the Multi-Effect Adsorptive Desalination process. A total of four types of reliability block diagrams were presented, and availability analysis was conducted based on them. The first form of a reliability block diagram is configured in series without any redundancy. The availability of the reliability block diagram composed of the serial system was found to be lower than the required availability. In order to increase availability, the redundancy to pumps and boiler are added to system. As a result of availability analysis, it was confirmed that designing desalination systems with redundancy to pump meets the 93% availability, which is typically required availability for various plants.