• Journal of the Korean Institute of Telematics and Electronics
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• v.7 no.4
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• pp.14-19
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• 1970

Transient phenomena in the p-n junction due to the selfheating effect of microplasma current have been investigated for the cases of small current and of large current. For the small current case, the temperature rise of the microplasma site is proportional to the current decrease and a unique time constant could be defined. However, the situation was complicated for the case of large current, and the time constant was not uniquely defined.

• Communications for Statistical Applications and Methods
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• v.13 no.2
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• pp.327-341
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• 2006

Winkler (1990, 2001), Sitter and Skinner (1994), Wilson and Sitter (2002) present a method which applies linear programing to designing surveys with multi-way stratification, primarily in situation where the desired sample size is less than or only slightly larger than the total number of stratification cells. A comparison is made with existing methods both by illustrating the sampling schemes generated for specific examples, by evaluating sample mean, variance estimation, and mean squared errors, and by simulating sample mean for all methods. The computations required can, however, increase rapidly as the number of cells in the multi-way classification increase. In this article their approach is applied to multi-way stratification using real data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3577-3581
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• 2013

In order to analyze a pile constructed by vibro-hammer, vibrational characteristics of vibro-hammer should be investigated first. Analytical studies were conducted in order to investigate vibrational properties of vibro-hammer. It is thought that the concept of acting the spring force to the pile head should be replaced by the concept of considering the lumped mass of the exciter and the pile. For the situation of free vibration, spring force increase with increase of spring constant and the amplitude is little affected by the spring constant. Also for the situation of free vibration, amplitude is inversely proportional to the increase of mass of the exciter and it can be seen that spring force increase with amplitude by the same ratio. It can be seen that directions of the spring force and displacement are opposite to that of rotating mass.

• Journal of the Korean Chemical Society
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• v.9 no.4
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• pp.179-184
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• 1965

Korean acid clays and Japanese acid clay were 1 N KCl solution and then their acidities were determined by measuring pH of the filtrates produced. And on examining the effect of neutral salt solution, such as KCl, NaCl, $BaCl_2,\;Pb(NO_3)_2\;and\;CuSO_4$, on the acidity, it was found that the effect decreased in order mentioned above and this situation proved to be in accord with Lyotrope series, i.e., the order of $K^+>Na^+>Ba^{++}>Pb^{++}>Cu^{++}.$ And after adsorbing cation, $Al_2O_3\;and\;Fe_2O_3$ which dissolved out of acid clay were measured, with the result that the amounts dissolved out were nearly proportional to acidity. This result accords with Kobayashi and Yamamoto's theory that the cause for acidity of clays is due to the fact that HCl which is formed initially by exchange of cation reacts with solid clay, and then chlorides dissolved out bring about hydrolysis, then resulting in the second formation of HCl. On measuring the rate which acid clay adsorbed dye in aqueous solution of basic and acid dyes, it was found that acid dye had no relation to acidity, and though it was not adsorbed by acid clay, the adsorption rate of basic dye was proportional to acidity. After adsorbing basic dye, pH was proportional to both acidity of solid acid and its adsorption rate of dye. Hence, it was concluded that the adsorption of basic dye was in accord with adsorption mechanism of neutral salt. This study led to find the acidic cause of solid acid and its adsorption mechanism of dye in aqueous solution.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.11a
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• pp.161-164
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• 2005

Mobile device users are sensitive to pay telecommunication charge for downloading Internet data, because the cost is proportional to the amount of data received. If there are device users who want to download the same content, they may cooperate each other to form an ad hoc network and share the partially downloaded content in order to reduce the amount of data downloaded. Each mobile device, called a peer, downloads a specific portion of the whole content using fee-based telecommunication channel, and exchanges the portion with other peers with free ad hoc channel in order that all participating peers are able to reconstruct the whole content in this situation, al1 participating peers become senders and receivers at the same time. In order to distribute the partial content to other peers, the ad hoc network requires a control led distribution mechanism. This paper introduces the per-peer-based distribution method in which one designated peer can transmit partial data to its neighbors at a time. Simulation results show that 90$\%$ of the telecommunication cost is saved with as few as 10 peers .

• Communications for Statistical Applications and Methods
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• v.15 no.6
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• pp.883-897
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• 2008

This paper provides correct informations inflecting the present situation using the sample design in population that the National Statistical Office puts in operation of the mining and manufacturing industry statistical survey in 2006. This paper proposes new sampling design which is able to grasp business fluctuations and provide basic data for the rearing policy and management of the material industry and components industry. These sample design are the modified cut-off method and multivariate Neyman allocation using principal components and sampling method is the probability proportional systematic sampling.

• Journal of Biomedical Engineering Research
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• v.38 no.4
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• pp.211-217
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• 2017

During the emergency situation such as cardiac arrest, cardiopulmonary resuscitation(CPR) is the most important treatment to maintain patient's blood circulation. Since the quality of CPR can not be easily measured or evaluated by the eye, an assistive device with an accelerometer can help to assess the pressure depth of CPR. In this study, we propose a single frequency analysis method to reduce the error of the accelerometer by extracting only one frequency component from the Fourier transform process. To verify the effectiveness of the single frequency analysis, acceleration data at CPR conditions were measured at a sampling rate of 50 / sec using a wristband equipped with an acceleration sensor. Then, We compared the existing distance estimation method and the single frequency analysis method using the measured data. The amplitude value proportional to the compression depth was obtained by applying the single frequency analysis method.

• Journal of the Korean Data and Information Science Society
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• v.26 no.3
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• pp.569-580
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• 2015

Log-rank is widely used for testing equality of two survival functions, and this method is efficient only under the proportional hazard assumption. However, crossing survival functions are common in practice. Therefore, many approaches have been suggested to test equality of them. This study considered several methods; Renyi type test, modified Kolmogorov-Smirnov and Cramer-von Mises test, and weighted Log-rank test, which can be applied when the survival functions cross, and simulated power of those methods. Based on the simulation results, we provide the useful information to choose a suitable approach in a given situation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.6
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• pp.99-105
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• 2014

Power transformers are applied throughout the power system to connect systems of different voltage to one another. Since a ratio differential relay offers high sensitivity in detection of internal faults in power transformers, it is widely used in the main protection system. The use of nonlinear devices such as rectifiers and other devices utilizing solid state switching have been increased in industry during recent years. For nonlinear loads, the load current is not proportional to the instantaneous voltage. This situation creates harmonic distortion on the system. The harmonic could differential relay misoperation if not recognized. This paper aims at analyzing and probing into the influences of harmonics on a ratio differential relay for power transformer protection.

• Journal of Korean Society of Steel Construction
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• v.9 no.3 s.32
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• pp.421-430
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• 1997

In this study, the static and the fatigue tests were performed with high tension bolted joints, of which the surfaces were spread with inorganic zinc-primer after shot-blast, and milling surface, and steel-natural surface, difference of friction surface condition were examined by comparing the esults of tests. From the result of synthetical investigation of this study. it is proper that using the torque management method in order to introduce design axial force to blots, and the provision of specifications that initial axial forces must be 110% of design axial forces is proper. Decreasing ratio of axial forces to initial force is proportional to common lorgarithms of time progress, it converge constant value after 20 hours, and decreasing ratio is little related to the roughness of friction surface. Sliding coefficient of milling, spreading inorganic zinc-primer, just producting is great in order and sliding forces are dependent on the applied axial forces, but if the applied axial forces are great, sliding coefficient become small by a loss of roughness. So it is confirmed that relation between the applied axial forces and the sliding forces are not proportional linearly. From the result of estimation on fatigue strength, all specimens satisfy the specifications with B-grade and milling surface is lower than the others about 14% in fatigue strength because in milling surface lose the function of friction-types joints at lower number of cycles. From the result of eximination for the distribution area of compressive force, friction area near to inside bolt is wider in the direction of stress than near to outside. It is guessed that this situation occurs because outside bolts firstly change from the friction connection to the bearing connection.