• Journal of the Korean Chemical Society
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• v.59 no.4
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• pp.271-279
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• 2015

The critical micelle concentration (CMC), the counter ion binding constant (B) and the aggregation number (N^* ) for the mixed micellization of sodium dodecanoate and sodium n-octanoate as two anionic surfactants have been investigated by means of electric conductivity and light scattering. As its experimental results are found to be deviated from ideal mixed model, thus two different kinds of regular solution models such as Rubingh and Motomura are used for interpreting our experimental data. The stability of the mixed micelles has been confirmed from the negative values of the standard Gibbs energy of mixed micellization ΔG^micel,0 over all compositions and the measured values of ΔG^micel,0 agreed with the theoretical ones within the experimental error.

• Bulletin of the Korean Chemical Society
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• v.19 no.1
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• pp.98-103
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• 1998

The crystal structure of dehydrated $Rb^+$-exchanged zeolite X, stoichiometry $Rb_{71}Na_{21}-X\; (Rb_{71}Na_{21}Si_{100}Al_{92}O_{384})$ per unit cell, has been determined from single-crystal X-ray diffraction date gathered by counter methods. The structure was solved and refined in the cubic space group Fd3, a=25.007(3) Å at 21(1) ℃. The crystal was prepared by ion exchange in a flowing stream using a 0.05 M aqueous RbOH solution (pH=12.7). The crystal was then dehydrated at 360 ℃ and $2{\times}10^{-6}$ torr for two days. The structure was refined to the final error indices, $R_1=0.047$ and $R_2=0.040$ with 239 reflections for which I> 3σ(I). In this structure, 71 $Rb^+$ ions per unit cell are found at six different crystallographic sites and 21 $Na^+$ ions per unit cell are found at two different crystallographic sites. Four and a half $Rb^+$ ions are located at site Ⅰ, the center of the hexagonal prism. Nine $Rb^+$ ions are found at site Ⅰ' in the sodalite cavity (Rb-O=2.910(15) Å and O-Rb-O=78.1(4)°). Eighteen $Rb^+$ ions are found at site Ⅱ in the supercage (Rb-O=2.789(9) Å and O-Rb-O=92.1(4)°). Two and a half $Rb^+$ ions, which lie at site Ⅱ', are recessed ca. 2.07 Å into the sodalite cavity from their three O(2) oxygen planes (Rb-O=3.105(37) Å and O-Rb-O=80.6(5)°). Thirty-two $Rb^+$ ions are found at site Ⅲ deep in the supercage (Rb-O=2.918(12) Å and O-Rb-O=71.9(4)°), and five $Rb^+$ ions are found at site Ⅲ'. Seven $Na^+$ ions also lie at site Ⅰ. Fourteen $Na^+$ ions are found at site Ⅱ in the supercage (Na-O=2.350(19) Å and O-Na-O=117.5(6)°).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.7
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• pp.816-821
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• 2019

A counter-type time-to-digital converter was designed using a dual edge T flip-flop. The time-to-digital converter was designed with a $0.18{\mu}m$ CMOS process at a supply voltage of 1.5 volts. In a typical time-to-digital converter, when the period of the clock is T, a conversion error corresponding to the period of the clock occurs due to the asynchronism between the input signal and the clock. However, the clock of the time-to-digital converter proposed in this paper is generated in synchronization with the start signal which is the input signal. As a result, conversion errors that may occur due to asynchronization of the start signal and the clock do not occur. The flip-flops constituting the counters are composed of dual-edge flip-flops operating at the positive and negative edges of the clock to improve the resolution.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.273-284
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• 2023

This study is centered on the combined use of LiDAR(Light Detection and Ranging) and AR(Augmented Reality) technologies during vertical and horizontal frame measurements in construction projects. The intention is to enhance the quality control procedure, elevate accuracy, and curtail manual labor along with time expenditure. Present methods for accuracy inspection in frame construction often grapple with reliability concerns due to subjective interpretation and the scope for human error. This research recommends the application of LiDAR and AR technologies to counter these issues and augment the efficiency of the inspection process, along with facilitating the dissemination of results. The suggested technique involves the collection of 3D point cloud data of the frame utilizing LiDAR and leveraging this data for checks on construction accuracy. Furthermore, the inspection outcomes are fed into a BIM (Building Information Modeling) model, and the results are visualized via AR. Upon juxtaposing this methodology with the current approach, it is evident that it offers benefits in terms of objective inspection, speed, precise result sharing, and potential enhancements to the overall quality and productivity of construction projects.

• The Korean Journal of Financial Management
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• v.20 no.2
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• pp.181-200
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• 2003

Comovement of international stock market prices has been lately a major controversy in the global stock market. This paper explores whether the common trend has really existed among the US, Japan and Korea's stock markets using the econometric techniques such as VAR, VECM as applied. Pair of indices from the exchange market and the over-the-counter market in each country has been tested, and the exchange market only has been turned out that the common trend existed. The dynamic analyses using the Granger causality test, impulse response function, and the forecast error decomposition have followed to show that the US stock market has played some important role in the Korea and Japan's market in the exchange as well as in the OTC market. The results of the paper imply that the more careful investigation with respect to the co-integration may be necessary in the global market integration studies.

• Journal of KIISE:Information Networking
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• v.29 no.4
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• pp.447-458
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• 2002

In this paper, we design and implement Wireless Transaction Protocol(WTP) and evaluate it for wireless transaction processing in mobile computing environments. The design and implementation of WTP are based on the coroutine model that might be suitable for light-weight portable devices. We test the compatibility between our product and the other products such as Nokia, Kannel and WinWAP For the evaluation of WTP, we use an Internet simulator that can arbitrary generate random wireless errors based on the Gilbert model. In our experiment, the performance of WTP is measured and compared to those of Transmission Control Protocol(TCP) and TCP for Transactions. The experiment shows that WTP outperforms the other two protocols for wireless transaction processing in terms of throughput and delay. Especially, WTP shows much higher performance In ease of high error rate and high probability of burst errors. This comes from the fact that WTP uses a small number of packets to process a transaction compared to the other two protocols and introduces a fixed time interval for retransmission instead of the exponential backoff algorithm. The experiment also shows that the WTP performance is optimized when the retransmission counter is set to 5 or 6 in case of high burst error rate.

• Journal of Radiation Protection and Research
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• v.22 no.1
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• pp.35-46
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• 1997

A simple and precise method of $^{14}C$ was developed to analyze $^{14}C$ in the environment samples using a commercially available $^{14}CO_2$ absorbent and a liquid scintillation counter. An air sampler and a combustion system were developed to collect HTO and $^{14}CO_2$ in the air and the biological samples simultaneously. The collection yield of $^{14}CO_2$ by the air sampler was in the range of 73-89% . The yield of the combustion system was 97%. In preparing samples for counting, the optimum ratio of $CO_2$ absorbent to the scintillator for mixing was 1:1. No variation of the specific activity of $^{14}C$ in the counting sample was observed up to 70 days after preparation of the samples. The detection limit for$^{14}C$ was 0.025 Bq/gC, which is the level applicable to the natural level of $^{14}C$. The analytical result of $^{14}C$ obtained by the present method were within ${\pm}6%$ of the relative error from the one by the benzene synthesis. The specific activity of $^{14}C$ in the air collected at Taejon during the period of October 1996 ranged from 0.26 to 0.27 Bq/gC. The specific activity of $^{14}C$ in the air collected at 1km from the Wolsong nuclear power plant a 679 MWe PHWR, was $0.54{\pm}0.03$ Bq/gC. The ranges of specific activities of $^{14}C$ in the pine needles and the vegetations from the areas around the Wolsong nuclear power plant were 0.56-0.67 Bq/gC and 0.23-1.41 Bq/gC, respectively.

• Journal of Radiation Protection and Research
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• v.33 no.1
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• pp.13-20
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• 2008

The flow rate measurements in a multi-phase flow pipeline were evaluated quantitatively by means of a clamp-on sealed radioisotope based on a cross correlation signal processing technique. The flow rates were calculated by a determination of the transit time between two sealed gamma sources by using a cross correlation function following FFT filtering, then corrected with vapor fraction in the pipeline which was measured by the ${\gamma}$-ray attenuation method. The pipeline model was manufactured by acrylic resin(ID. 8 cm, L=3.5 m, t=10 mm), and the multi-phase flow patterns were realized by an injection of compressed $N_2$ gas. Two sealed gamma sources of $^{137}Cs$ (E=0.662 MeV, ${\Gamma}$ $factor=0.326\;R{\cdot}h^{-1}{\cdot}m^2{\cdot}Ci^{-1}$) of 20 mCi and 17 mCi, and radiation detectors of $2"{\times}2"$ NaI(Tl) scintillation counter (Eberline, SP-3) were used for this study. Under the given conditions(the distance between two sources: 4D(D; inner diameter), N/S ratio: $0.12{\sim}0.15$, sampling time ${\Delta}t$: 4msec), the measured flow rates showed the maximum. relative error of 1.7 % when compared to the real ones through the vapor content corrections($6.1\;%{\sim}9.2\;%$). From a subsequent experiment, it was proven that the closer the distance between the two sealed sources is, the more precise the measured flow rates are. Provided additional studies related to the selection of radioisotopes their activity, and an optimization of the experimental geometry are carried out, it is anticipated that a radioisotope application for flow rate measurements can be used as an important tool for monitoring multi-phase facilities belonging to petrochemical and refinery industries and contributes economically in the light of maintenance and control of them.

• Journal of IKEEE
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• v.22 no.3
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• pp.638-644
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• 2018

In this paper, we develop a measurement system that uses 3D Scintillator and NaI(TI) Detector to 3-dimensionally identify the location of multiple radiation sources in moving vehicle loads. The radiation measurement system consists of radiation measurement (plastic scintillator), 2-channel Pulse Counter Board, nuclide analysis (NaI(TI) detector) and 1 channel MCA Board. The source locator algorithm calculates the coordinate value of the ratio of the CPS value($1/r^2$) of the source according to the angle(${\theta}$) in inverse proportion to the square of the distance(X, Y) through the SVM classification. The coordinate values are input every predetermined period of the spectrum, and after analyzing the spectrum per unit cycle, the position of the nuclide at the time is calculated by determining whether or not the nuclide is present in the remaining part except for the background area. As a result of the position discrimination test, the error within the international standard of ${\pm}1m$ was shown. Thus, the utility of the proposed system has been demonstrated.

• Korean Journal of Crystallography
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• v.2 no.1
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• pp.17-22
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• 1991

The crystal structure of an acetylene sorption complex of vacuum dehydrated fully Cda+ _exchanged zeolite A has been determined from three-dimensional X-ray diffraction data gathered by counter method. The structure was solved and refined in the cubic space group Pm3m at 294(1) K, a=12.202(3) A and Z=1. We crystal was prepared by dehydration at 723 K and 2.67×104 Pa for 2 days, followed by exposure to 1.60×104 Pa of acetylene gas at 298(1) K. All six Cd2+ions per unit cell are associated with 6-oxgen rings of the aluminosilicate framework. They are distributed over two distinguished threefold axes of unit cell; two of these Cd2+ ions are recessed 0.694 into the sodalite unit from (111) plane of three 0(3)'s and each approaches three framework oxides; the other four Cd2+ ions extend approximately 0.586A into the large cavity. The four Cd2+ ions are in a near tetrahedral environment, 2.220(9)A from·three framework oxide ions and 2.74(7) A from each carbon atom of an acetylene molecule(which is here counted as a monodentate ligand). Full matrix least squares refinement converged to the final error indices R1=0.093 and R2=0.105 using the 292 independent reflections for which I>3σ(I).