• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.637-644
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• 2006

Acceleration time history used in the seismic analysis of nuclear porter plant structure should envelop a target power spectral density (PSD) function in addition to design response spectrum. Current regulation guide defines the target PSD function only for the U.S. URC RG 1.60 Design Response Spectrum. This paper proposes a technical scheme to obtain the target PSD function compatible with generally defined design response spectrum. The scheme includes the methodology for design-spectrum compatible motion history in order to minimize the variation of the derived target PSD function. The PSD calculation procedure follows simple and practical methods allowed within regulation. Effectiveness of the proposed scheme is identified through an example problem. The design response spectrum In the example is based on U.S. NRC RG 1.60 but amplifies the spectral acceleration amplitudes above 9Hz. The target PSD function with little variation can be constructed with the reduced time history ensemble.

• Journal of Yeungnam Medical Science
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• v.35 no.1
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• pp.17-26
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• 2018

Transcatheter aortic valve implantation (TAVI) has evolved from a challenging intervention to a standardized, simple, and streamlined procedure with over 350,000 procedures performed in over 70 countries. It is now a novel alternative to surgical aortic valve replacement in patients with intermediate surgical risk and its indications have been expanded to cohorts with bicuspid aortic valves, low surgical risk, and younger age and fewer comorbidities. Attention should be paid to further reducing remaining complications, such as paravalvular aortic regurgitation, conduction abnormalities, cardiac tamponade, and stroke. The aim of this review is to provide an overview on the rapidly changing field of TAVI treatment and to explore past achievements, current issues, and future perspectives of this treatment modality.

• Bulletin of the Korean Chemical Society
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• v.19 no.1
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• pp.50-56
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• 1998

A solvent sublation was studied for the determination of trace Cd, Co, Cu and Ni in water samples. Ammonium pyrrolidine dithiocarbamate (APDC) was used as a complexing agent. Experimental conditions such as pH of solution, amounts of APDC, the type and amount of surfactant, the type of solvent, etc. were optimized for the effective sublation of analytes. After metal-PDC complexes were formed in sample solutions of pH 2.5, the precipitate-type complexes were floated in a flotation cell with an aid of sodium lauryl sulfate as a surfactant and by bubbling with nitrogen gas. The precipitates were dissolved and separated into the surface layer of methyl iso-butyl ketone (MIBK). The analytes preconcentrated were determined by a graphite furnace atomic absorption spectrophotometry (GF-AAS). Extractability of each element was 88% for Cd(Ⅱ), 86% for Co(Ⅱ), 95% for Cu(Ⅱ) and 76% for Ni(Ⅱ), respectively. And this procedure was applied to the analysis of real samples. From the recoveries of more than 92%, it was concluded that this method could be simple and applicable for the determination of trace elements in various water samples of a large volume.

• Korean Journal of Remote Sensing
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• v.19 no.5
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• pp.403-409
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• 2003

Since SPOT4 satellite contained VEGETATION 1 sensor launched, the noise in VEGETATION data was occasionally arisen a difficulty for the data traitement. Blind line noise types were studied in VEGETATION-l short wave infrared channel(SWIR). In order to provide a precis product, the procedure for removing this noise is strongly recommended. In the case that the blind values are clearly distinguished from contamination-free values a simple threshold method was applied, while a changeable threshold method was used for the blind value mixed with contamination-free values. New algorithm presented in this study is consists of two method for each type of SWIR blind. After removing blind line, there were again some residual pixels of blind, because the threshold is not determinated sufficiently low. Lower threshold could remove the blind line as well as the contamination-free pixels. Nevertheless, the results showed a good qualitative improvement as compared with other algorithm.

• Bulletin of the Korean Chemical Society
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• v.9 no.6
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• pp.379-381
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• 1988

Racemic nuciferal(1) and nuciferol(2), the terpenic natural perfumeries, have been synthesized by a simple procedure. The benzylic halide 6; 1-(1-chloroethyl)-4-methylbenzene, was prepared by converting p-tolualdehyde(4) into 1-(p-tolyl)-1-ethanol(5), followed by convertion of 5 into corresponding chloride. The Grignard reagent of 6 was reacted with the bromoacetal 7, 2-(2-bromoethyl)-1,3-dioxolane, to give a crosscoupling product 8, which was hydrolysed to 4-(p-tolyl)-pentanal (9). The Wittig reaction of isopropylide 10 with 9 yielded arcurcumen(11). The stereospecific allylic oxidation of the gem-dimethyl olefin 11 with selenium dioxide afforded a trans-aldehyde, (${\pm}$)-1, which was reduced to corresponding alcohol, (${\pm}$)-2.

• Bulletin of the Korean Chemical Society
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• v.21 no.11
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• pp.1101-1105
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• 2000

A simultaneous determination method of BTEX (benzene, toluene, ethylbenzene, o,m.p-xylene) and TPH (kerosene, diesel, jet fuel and bunker C) in soil with gas chromatography/flame ionization detection (GC-FID) was described. The effects of extracti on method, extraction solvent, solvent volume and extraction time on the extraction performance were studied. A sonication method was simpler and more efficient than Soxhlet or shaking methods. Sonication with 10 mL of acetone/methylene chloride (1 : 1, v/v) for 10 min was found to be optimal extraction conditions for 20 g of soil. Peak shapes and quantification of BTEX and TPH were excellent, with linear calibration curves over a wide range of 1-500 mg/L for BTEX and 10-5000 mg/L for TPH. Good reproducibilities by sonication were obtained, with the RSD values below 10%. By using about 20 g of soil, detection limits were 0.8 mg/L for BTEX and 10 mg/L for TPH. The advantages of this procedure are the use of simple and common equipment, reduced volumes of organic solvents, rapid extraction periods of less than 20 min, and simultaneous analysis of volatile and semivolatile compounds.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.617-618
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• 1998

A simple and reproducible pretreatment method was developed for the determination of dioxins in milk sample. Liquid-liquid extraction (LLE) was used for the initial extraction of the analyte from milk. For the elimination of interferences coextracted from milk, acid treatment followed by multilayer silica gel, and then alumina column clean-up were performed. The clean extract could be obtained without carbon column or high performance liquid chromatographic (HPLC) clean-up procedure. Polychlorinated biphenyles (PCBs) and dioxins were separated on neutral alumina activated at 180 ℃ for 12 hours. The final extract was analyzed by HPLC and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). The recovery of dioxins spiked in milk at 75-300 ppt level was 83.3-98.9% and their relative standard deviation was 4.1-14%.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.619-624
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• 1998

A simple and reproducible pretreatment method was developed for the determination of dioxins in milk sample. Liquid-liquid extraction (LLE) was used for the initial extraction of the analyte from milk. For the elimination of interferences coextracted from milk, acid treatment followed by multilayer silica gel, and then alumina column clean-up were performed. The clean extract could be obtained without carbon column or high performance liquid chromatographic (HPLC) clean-up procedure. Polychlorinated biphenyles (PCBS) and dioxins were separated on neutral alumina activated at 180 ℃ for 12 hours. The final extract was analyzed by HPLC and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). The recovery of dioxins spiked in milk at 75-300 ppt level was 83.3-98.9% and their relative standard deviation was 4.1-14%.

• Structural Engineering and Mechanics
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• v.7 no.6
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• pp.551-559
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• 1999

This paper presents some simple thinking on an age-old question that given a bridge of a certain span and loading, from the point of view of the structural efficiency, where should the bridge deck be positioned? Generally, this decision is made for other reasons than structural efficiency such as aesthetics and the analyst is often presented with a fait accompli. Using the recently invented Evolutional Structural Optimisation (ESO) method, it is possible to demonstrate that having the deck at different vertical locations can lead to a very different mass and shape for each structural form resembling cable-stayed and cable-truss bridges. By monitoring a performance index which is the function of stresses and volume of discretised finite elements, the best optimised structure can be easily determined and the bridge deck positioning problem can be efficiently solved without resorting to any complex analysis procedures.

• Structural Engineering and Mechanics
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• v.20 no.4
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• pp.435-450
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• 2005

Here, the dynamic instability characteristics of aero-thermo-mechanically stressed functionally graded plates are investigated using finite element procedure. Temperature field is assumed to be a uniform distribution over the plate surface and varied in thickness direction only. Material properties are assumed to be temperature dependent and graded in the thickness direction according to simple power law distribution. For the numerical illustrations, silicon nitride/stainless steel is considered as functionally graded material. The aerodynamic pressure is evaluated based on first-order high Mach number approximation to the linear potential flow theory. The boundaries of the instability region are obtained using the principle of Bolotin's method and are conveniently represented in the non-dimensional excitation frequency-load amplitude plane. The variation dynamic instability width is highlighted considering various parameters such as gradient index, temperature, aerodynamic and mechanical loads, thickness and aspect ratios, and boundary condition.