• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.87-94
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• 1999

Empirical design is still used to avoid a structural damage because impact phenomenon and structural behaviour due to wave impact load can not examined accurately. The damage due to wave impact load is largely affected by impact pressure impulse and impact load area. The objective of this study is, as the second step, to develop an efficient scantling program of bow flare structure, and to predict its impact load area by comparing maximum dented deformations at center of idealized panel structure model of bow flare structure of 300k DWT VLCC using LS/DYNA3D code, which will be used for its verification of dynamic structural analysis, as the next step. Through this study, the impact load area was estimated as $1.5s{\times}1.5s$ stiffener space(s) in the case of panel with stiffeners and as $2.5s{\times}2.5s$, with stringers, under impact pressure curve with peak height 6.5MPa, tail height 1.0MPa, and duration time 5.0msec.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.77-86
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• 1999

The bow flare structure of a ship is designed considering wave impact loads largely caused by relative motion of the ship and wave at rough sea. Empirical design is still used because impact phenomenon and structural behaviour due to wave impact load can not examined accurately. The objective of this study is, as the first step, to predict wave impact loads giving the structural damages to the bow flare structure from the damage data inversely, using dynamic nonlinear finite element code LS/DYNA3D, and to perform various parametric studies of wave impact pressure curve for its characteristics, such as peak height, duration time, tail height, rise time, etc.. The followings were obtained from this study: Dynamic structural responses against wave impact loads are largely affected by impact pressure impulse whose amount during duration time until peak deformation is very important.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.2
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• pp.153-160
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• 2015

Pipelines are one of the most important structures in subsea equipment. It is the main equipment for transportation of crude oil and natural gas to the downstream facilities. Crude oil and natural gas leak will be carry out not only political and financial issues but also pollution to the environment. Inaccurate predictions of corrosion behavior will make hazardous consequences. The serviceability assessment of corroded structures is essential especially for subsea pipelines. As corrosion is concerned, the effects of failure due to significant reduction will make it hard to the pipeline operator to maintain the serviceability of pipelines. In this paper, the serviceability assessment of corroded crude oil pipeline is performed using the industry design code (Shell92, DNV RP F101, ASME B31G, BS 7910, PCORRC) and FEA depending on corrosion area. In last step, the future integrity of the subsea crude oil pipeline is assessed to predict the remaining year in service of crude oil pipelines.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.27.1-27.1
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• 2011

We obtained the spectra of 93 Planet host stars and 73 normal field stars in F, G, K type using BOES at BOAO. We measured the equivalent width of Fe and 25 elements lines using the automatic EW measurement program, TAME(Tools for Automatic Measurement of Equivalent-widths) and estimated the elemental abundances by synth and abfind driver of MOOG code. Since the absence of planets in the normal field stars cannot be "completely" proved, this work focused on the chemical abundances and planet properties of planet host stars, which have the massive planets close to the parent star relatively. We carried out an investigation for the difference of abundances between stars with "Hot Jupiter" and normal field stars with no known planets. We examined the chemical composition of 25 elements, such as C, N, O, S, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu by EW measurements, and the S abundances were estimated using synthetic spectrum. We have found that [Mg/Fe] and [Al/Fe] for planet host stars have lower limit comparing with those of comparison stars, and [Ca/Fe] of host star with Neptunian planets is relatively lower than the other host stars with massive planets. We have performed the Kolmogorov-Smirnov test, and examined the ratio of planet host stars to all stars for each bin of [X/H]. As a result, we noted that the O, Si, and Ca abfor undances are strongly related with the presence of planets.

• International Journal of Fluid Machinery and Systems
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• v.3 no.1
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• pp.11-19
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• 2010

The performance of the crossover system of a centrifugal compressor stage consisting of static components of $180^{\circ}$ U-bend, return channel vanes and exit ducting with a $90^{\circ}$ bend is investigated. This study is confined to the assessment of performance of the crossover system by varying the shape of the return channel vanes. For this purpose two different types of Return Channel Vanes (RCV1 and RCV2) were experimentally investigated. The performance of the crossover system is discussed in terms of total pressure loss coefficient, static pressure recovery coefficient and vane surface pressure distribution. The experimentation was carried out on a test setup in which static swirl vanes were used to simulate the flow at the exit of an actual centrifugal compressor impeller with a design flow coefficient of 0.053. The swirl vanes are connected to a mechanism with which the flow angle at the inlet of U-bend could be altered. The measurements were taken at five different operating conditions varying from 70% to 120% of design flow rate. On an overall assessment RCV1 is found to give better performance in comparison to RCV2 for different U-bend inlet flow angles. The performance of RCV2 was verified using numerical studies with the help of a CFD Code. Three dimensional sector models were used for simulating the flow through the crossover system. The turbulence was predicted with standard k-$\varepsilon$, 2-equation model. The iso-Mach contour plots on different planes and development of secondary flows were visualized through this study.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.3-8
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• 2006

The next decade promises drastic improvements and additions to global navigation satellite systems (GNSS). Plans for GPS modernization include a civilian code measurement on the L2 frequency and a new L5 signal at 1176.45 MHz. Current speculations indicate that a fully operational constellation with these improvements could be available by 2013. Simultaneously, the Galileo Joint Undertaking is in the development and validation stages of introducing a parallel GNSS called Galileo. Galileo will also transmit freely available satellite navigation signals on three frequencies and is scheduled to be fully operational as early as 2008. In other words, a dual system receiver (e.g., GPS+GALILEO) for general users can access six civil frequencies transmitted by at least fifty eights navigation satellites in space. The advent of GALILEO and the modernization of GPS raise a lot of attention to the study of the compatibility and interoperability of the two systems. A number of performance analyses have been conducted in a global scale with respect to availability, reliability, accuracy and integrity in different simulated scenarios (such as open sky and urban canyons) for the two systems individually and when integrated. Therefore, the scope of this article aims at providing the technical benefits analysis for Taiwan specifically in terms of the performance indices mentioned above in a local scale, especially in typical urban canyon scenarios. The conclusions gained by this study will be applied by the Land Survey Bureau of Taiwanese as the guideline for developing future GNSS tracking facilities and dual GNSS processing module for precise surveying applications in static and kinematic modes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.2107-2112
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• 2006

As growing up of elderly population, the interesting on healthcare system in normal life using W is increasing. An integrated u-healthcare service architecture with IEEE 802.11 and IEEE 802.15.4 based sensor network and code divisi(m multiple access(CDMA) public mobile telecommunication networks was designed and developed. Sensor nodes with electrocardiogram(ECG), body core temperature sensors are attached on the patients' body. The healthcare parameters are transferred to web server via CDMA mobile network or through existed LAN network. The existed LAN network is suggested to be used for continuous monitoring of patient's health status in hospital while mobile networks can be used for general purpose at home or outdoor where infra networks unavailable. This system enable healthcare personal to be able to continuously access, review, monitor and transmit the patients information whereever they are, whenever they want. And immediately check their status by using cellular phone and obtain detail information by communication with medical information server through CDMA. By using this developed integrated u-healthcare service architecture, we can monitor patients' health status for 24 hours.

• The KIPS Transactions:PartA
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• v.9A no.4
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• pp.573-580
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• 2002

Reusing IPs requires interface protocol related tasks such as writing test benches and designing interface protocol conversion circuits, e.g. wrappers for IPs. The results of those tasks usually include IPC(interface protocol component)s for the corresponding IPs, similar to bus protocol components of the bus functional models. This paper proposes a methodology for the interface circuit design using synthesizable In that can be re-used. IPC recognizes or executes transactions over the given interface ports. So we present a transaction-oriented interface protocol description language, and a method to convert the description into an IPC in synthesizable VHDL code. With experiments, we show that the interface design using IPC does not cause significant area overhead compared with the interface design without IPC. The proposed IPC-based approach can be employed to reduce the interface design time since the designers can reuse IPCs without understanding the detailed interface protocols.

• Nuclear Engineering and Technology
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• v.50 no.2
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• pp.229-236
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• 2018

Accident-tolerant fuels (ATFs) are currently of high interest to researchers in the nuclear industry and in governmental and international organizations. One widely studied accident-tolerant fuel concept is multilayer cladding (also known as coated cladding). This concept is based on a traditional Zr-based alloy (Zircaloy-4, M5, E110, ZIRLO etc.) serving as a substrate. Different protective materials are applied to the substrate surface by various techniques, thus enhancing the accident tolerance of the fuel. This study focuses on the results of testing of Zircaloy-4 coated with pure chromium metal using the cold spray (CS) technique. In comparison with other deposition methods, e.g., Physical vapor deposition (PVD), laser coating, or Chemical vapor deposition techniques (CVD), the CS technique is more cost efficient due to lower energy consumption and high deposition rates, making it more suitable for industry-scale production. The Cr-coated samples were tested at different conditions ($500^{\circ}C$ steam, $1200^{\circ}C$ steam, and Pressurized water reactor (PWR) pressurization test) and were precharacterized and postcharacterized by various techniques, such as scanning electron microscopy, Energy-dispersive X-ray spectroscopy (EDX), or nanoindentation; results are discussed. Results of the steady-state fuel performance simulations using the Bison code predicted the concept's feasibility. It is concluded that CS Cr coating has high potential benefits but requires further optimization and out-of-pile and in-pile testing.

• Journal of Radiation Industry
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• v.5 no.4
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• pp.325-330
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• 2011

To predict the details of flow in industrial process unit, single photon emission computed tomography (SPECT) is a promising technique. Recently, industrial SPECT based on medical system has developed by researchers of the Korea Atomic Energy Research Institute (KAERI) and Hanyang University. In the present study, to confirm the effect of the number of detectors on image quality, and determine the optimal number of detectors in industrial SPECT, industrial SPECT system with various geometries were evaluated by the Monte Carlo simulation. CsI(Tl) detectors ($12mm{\times}12mm{\times}20mm$) with collimators (the geometric resolution of collimator $R_g$ was 4 cm at the center of the 30 cm diameter cylindrical vessel object) were modeled in a hexagonal array, and the point sources of $^{99m}Tc$, $^{68}Ga$, and $^{137}Cs$ were simulated at the center of the cylindrical vessel object using the MCNPX code. Then, the reconstruction images of each geometry were reconstructed using the expectation maximization (EM) algorithm. In this study, the reciprocity theorem was used to improve computation time required for system matrix of the EM algorithm. The result shows that the resolution of the reconstructed image was significantly improved by increasing the number of detectors in industrial SPECT system and more than 60 detectors will be required for the resolution of the reconstructed image.