• Journal of Korean Society on Water Environment
• /
• v.22 no.1
• /
• pp.110-115
• /
• 2006

Flooding situation of Sutak basin was simulated and simulation seemed to be consistent with the real flooding situation in terms of high water levels and timings of flooding. The flood simulation model was used to evaluate alternatives to mitigate flooding problems in Sutak basin. From the evaluation of flood mitigation plans, it was found that combined operation of Sutak and Inchang pumping stations through partial diversion of inflow of Sutak pumping station to Inchang pumping station was the most effective one among the suggested mitigation plans. About 500 meter diversion channel will be needed to send 30% of Sutak pumping station inflow to Inchang pumping station. This will reduce overload of Sutak pumping station and the storage capacity of Inchang pumping station will be more efficiently utilized.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.12
• /
• pp.24-30
• /
• 2010

The super-resolution near-field structure (super-RENS) disc system is the most promising one for next-generation optical data storage systems to succeed the Blu-ray disc (BD). In this paper, we apply the simplicial canonical piecewise-linear (SCPWL) model to modeling super-RENS read-out signals since reliable and accurate channel modeling is essential for performance analysis and development of equalizers for super-RENS systems. The validity of this model is verified using radio frequency (RF) signal samples obtained from a super-RENS disc, The experiment results on modeling indicate that the SCPWL model can be efficiently utilized for the nonlinear modeling of the super-RENS systems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.05a
• /
• pp.409-411
• /
• 2016

Salt and pepper noise is caused by various causes such as camera malfunction, storage media memory error, and transmission channel error. Representative filters to remove salt and pepper noise include SMF(standard median filter), CWMF(center weighted median filter), and AMF(adaptive median filter). However previous filters have inadequate noise removal characteristics in high density salt-and-pepper noise environment. Therefore the study suggested a composite filter which, through noise evaluation, preserves original pixels when the central pixel is non-noise, and uses spatial weighted value mask and median when there is noise.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.8
• /
• pp.426-431
• /
• 2015

The advantages of a printed circuit heat exchanger (PCHE) are the compactness and efficiency derived from its heat-transfer characteristics; furthermore, a PCHE for which a diffusion bonding method was used during production can be applied to extreme environments such as a cryogenic condition. In this study, a micro-channel PCHE fabricated by diffusion bonding was investigated in a cryogenic environment regarding its thermal performance and the pressure drop. The test rig consists of an LN2 storage tank, vaporizers, heaters, and a cold box, whereby the vaporized cryogenic nitrogen flows in hot and cold streams. The overall heat-transfer coefficients were evaluated and compared with traditional correlations. Lastly, we suggested the modified heat-transfer correlations for a PCHE in a cryogenic condition.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.11C
• /
• pp.896-900
• /
• 2010

We investigate the bit error rate against signal-to-noise ratio performance corresponding to track mis-registration for patterned media storage. The patterned media channels with and without soft underlayer are implemented, and we simulate using one-dimensional Viterbi detector and two-dimensional soft output Viterbi detector (SOVA) when the track mis-registration is 0% (on-track), 10%, 20%, 30%, and 40%. While the BER performance degrades approximate 0.3 ~ 0.5 dB at 10% track mis-registration, it degrades severe over 10% track mis-registration.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.2
• /
• pp.168-174
• /
• 2006

We investigated field-effect ion-transport devices based on carbon nanotubes by using classical molecular dynamics simulations under applied external force fields, and we present model schematics that can be applied to the nanoscale data storage devices and unipolar ionic field-effect transistors. As the applied external force field is increased, potassium ions rapidly flow through the nanochannel. Under low external force fields, thermal fluctuations of the nanochannels affect tunneling of the potassium ions whereas the effects of thermal fluctuations are negligible under high external force fields. Since the electric current conductivity increases when potassium ions are inserted into fullerenes or carbon nanotubes, the field effect due to the gate, which can modify the position of the potassium ions, changes the tunneling current between the drain and the source.

• Proceedings of the KSRS Conference
• /
• 2002.10a
• /
• pp.228-228
• /
• 2002

The DLS(Data Link System) is located in the PDTS(Payload Data Transmission Subsystem) of KOMPSAT-II, and its main function is to provide communication link with Ground Segment as a space segment. DLS receive the data of MSC, OBC from DCSU(Data Compression Storage Unit) and transmit to the Ground Station by X-Band RF link. DLS is consist of CCU(Channel Coding Unit), QTX(QPSK Transmitter, ASU(Antenna Switch Unit) CCU makes a packet for communication after several kind of data processing such like Ciphering, RS Coding. QTX transmit PDTS data by OQPSK. Modulation. ASU is the unit for reliability of antenna switching. So, DLS's function is consists of ciphering, RS coding, CCSDS packetizing, randomizing, modulation and switching to antenna. These DLS's functions are controlled by PMU(Payload Management Unit). All commands to DLS are sent by PMU and all telemetries of DLS are sent to the PMU. The PMU receives commands from OBC and sends telemetries to the OBC. The OBC communicates with Ground Station by S-Band RF link. This paper presents the on-orbit DLS operation concept through the ground segment.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.18 no.6B
• /
• pp.199-206
• /
• 2008

Broadcast encryption is a cryptographical primitive which is designed for a content provider to distribute contents to only privileged qualifying users through an insecure channel. Anyone who knows public keys can distribute contents by means of public key broadcast encryption whose technique can also be applicable to many other applications. In order to design public key broadcast encryption scheme, it should devise some methods that convert a broadcast encryption scheme based on symmetric key cryptosystem to a public key broadcast encryption. Up to this point, broadcast encryption scheme on trial for converting from symmetric key setting to asymmetric public key setting has been attempted by employing the Hierarchical Identity Based Encryption (HIBE) technique. However, this converting method is not optimal because some of the properties of HIBE are not quite fitting for public key broadcast schemes. In this paper, we proposed new converting method and an efficient public key broadcast encryption scheme Pub-PI which is obtained by adapting the new converting method to the PI scheme [10]. The transmission overhead of the Pub-PI is approximately 3r, where r is the number of revoked users. The storage size of Pub-PI is O($c^2$), where c is a system parameter of PI and the computation cost is 2 pairing computations.

• Journal of Sensor Science and Technology
• /
• v.32 no.1
• /
• pp.39-43
• /
• 2023

Microscale thermophysical property measurements of liquids have been developed considering the increasing interest in the thermal management of cooling systems and energy storage/transportation systems. To accurately predict the heat transfer performance, information on the thermal conductivity, heat capacity, and density is required. However, a simultaneous analysis of the thermophysical properties of small-volume liquids has rarely been considered. Recently, we proposed a new methodology to simultaneously analyze the aforementioned three intrinsic properties using heater-integrated fluidic resonators (HFRs) in an atmospheric pressure environment comprising a microchannel, resistive heater/thermometer, and mechanical resonator. Typically, the thermal conductivity and volumetric heat capacity are measured based on a temperature response resulting from heating using a resistive thermometer, and the specific heat capacity can be obtained from the volumetric heat capacity by using a resonance densitometer. In this study, we analyze methods to improve the thermophysical property measurement performance using HFRs, focusing on the effect of the ambience around the sensor. The analytical method is validated using a numerical analysis, whose results agree well with preliminary experimental results. In a vacuum environment, the thermal conductivity measurement performance is enhanced, except for the thermal conductivity range of most gases, and the sensitivity of the specific heat capacity measurement is enhanced owing to an increase in the time constant.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2009.04a
• /
• pp.278-281
• /
• 2009

KSTAR(Korea Superconducting Tokamak Advanced Research)는 고성능 플라즈마 연구를 위한 대형 연구실험 장치이다. 이러한 거대 장치에는 많은 시스템이 분산되어 연결되어 있으며 그 구조 역시 매우 복잡하여 시스템간의 인터페이스에 많은 제약과 어려움이 따른다. 이러한 복잡하고 다양한 시스템을 통합하고 여기서 발생하는 여러 종류의 데이터를 획득하기 위해서 KSTAR는 EPICS(Experimental Physics and Industrial Control System)라는 오픈소스 기반의 분산 제어용 미들웨어를 구축하였고 이를 기반으로 KSTAR 통합 제어 시스템을 개발 하였다. 2008년 KSTAR 최초 플라즈마 실험 기간 동안의 운전을 통해 EPICS 미들웨어와 EPICS channel archiver를 이용하여 다양한 24시간 연속 운전데이터를 안정적으로 저장하고 추출할 수 있음을 확인하였다. 논문에서는 시스템의 구축 방법 및 운전결과에 대해 기술하고자 한다.