• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.413-418
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• 2011

The thermodynamic properties of steam table are obtained by measurement or approximate calculation under appropriate assumptions. Therefore they are supposed to have basic measurement errors. And thermodynamic properties should be modeled through function approximation for using in numerical analysis. In order to make noised thermodynamic properties corresponding to measurement errors, random numbers are generated, adjusted to appropriate magnitudes and added to original thermodynamic properties. Both neural networks and quadratic spline interpolation method are introduced for function approximation of these modified thermodynamic properties in the saturated water based on pressure and temperature. In analysis spline interpolation method gives much less relative errors than neural networks at both ends of data. Excluding the both ends of data, the relative errors of neural networks is generally within ${\pm}0.2%$ and those of spline interpolation method within ${\pm}0.5$~1.5%. This means that the neural networks give smaller relative errors compared with quadratic spline interpolation method within range of use. From this fact it was confirmed that the neural networks trace the original values better than the quadratic interpolation method and neural networks are more appropriate method in modelling the saturated steam table.

• Analytical Science and Technology
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• v.9 no.1
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• pp.78-83
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• 1996

Hydrogen ion-selective membrane electrodes based on tribenzylamine(TBA), tetrabenzylethylenediamine(TBEDA), pentabenzyldiethylenetriamine(PBDETA) as neutral carriers were shown good selectivity and linearity in the range of pH 1~pH 9, pH 2~pH 12, pH 4~pH 12. The pH selectivity of this membrane electrodes have nothing relation with the numbers of unshared electron pair in TBA, TBEDA, PBDETA and were shown a slope of 43.8mV/pH, 46.9mV/pH, 43.6mV/pH respectively. The selectivity coefficients were determined by the separate solution method for alkali($Li^+$, $Na^+$, $K^+$), alkaline earth metal($Ba^{2+}$, $Ca^{2+}$, $Mg^{2+}$) and transition metal ions($Mn^{2+}$, $Co^{2+}$, $Ni^{2+}$, $Cu^{2+}$, $Zn^{2+}$). The membrane electrode based on TBEDA appeared the best results as hydrogen ion electrode.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.8-18
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• 2003

An experimental study is carried out to investigate the Reynolds number effects on the near-wake of an airfoil oscillating in pitch. An NACA 4412 airfoil is sinusoidally pitched about the quarter chord point between the angle of attack -6$^{\circ}$ and +6$^{\circ}$. A hot-wire anemometer is used to measure the turbulent intensity in the near-wake region of an NACA 4412 airfoil. The freestream velocities of present work are 3.4, 12.4, 26.2 m/s, and the corresponding Reynolds numbers are $5.3{\times}10^4,\;1.9{\times}10^5,\;4.1{\times}10^5$ and the reduced frequency is 0.1. Axial turbulent intensity profiles are presented to show the Reynolds number effects on the near-wake region behind an airfoil oscillating in pitch. All the cases in these measurements show that the turbulent intensities by the change of the Reynolds number are very large at the lowest Reynolds number $R_N=5.3{\times}10^4$; and are small at the other Reynolds number $(R_N=1.9{\times}10^5\;and\;4.1{\times}10^5)$ in the near-wake region. The significant difference of turbulent intensity between $R_N=5.3{\times}10^4,\;and\;1.9{\times}l0^5$ is observed. A critical value of the Reynolds number in the near-wake of an oscillating NACA 4412 airfoil which indicates laminar separation, no separation or turbulent separation exists in the range between $R_N=5.3{\times}10^4\;and\;1.9{\times}10^5$.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.213-218
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• 2015

In parallel with evolving information communication technology, M2M(Machine-to-Machine) industry has implemented multi-functional and high-performance systems, and made great strides with IoT(Internet of Things) and IoE(Internet of Everything). Authentication, confidentiality, anonymity, non-repudiation, data reliability, connectionless and traceability are prerequisites for communication security. Yet, the wireless transmission section in M2M communication is exposed to intruders' attacks. Any security issues attributable to M2M wireless communication protocols may lead to serious concerns including system faults, information leakage and privacy challenges. Therefore, mutual authentication and security are key components of protocol design. Recently, secure communication protocols have been regarded as highly important and explored as such. The present paper draws on hash function, random numbers, secret keys and session keys to design a secure communication protocol. Also, this paper tests the proposed protocol with a formal verification tool, Casper/FDR, to demonstrate its security against a range of intruders' attacks. In brief, the proposed protocol meets the security requirements, addressing the challenges without any problems.

• Publications of The Korean Astronomical Society
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• v.21 no.2
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• pp.67-74
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• 2006

We have developed a control electronics system for an infrared detector array of KASINICS (KASI Near Infrared Camera System), which is a new ground-based instrument of the Korea Astronomy and Space science Institute (KASI). Equipped with a $512{\times}512$ InSb array (ALADDIN III Quadrant, manufactured by Raytheon) sensitive from 1 to $5{\mu}m$, KASINICS will be used at J, H, Ks, and L-bands. The controller consists of DSP(Digital Signal Processor), Bias, Clock, and Video boards which are installed on a single VME-bus backplane. TMS320C6713DSP, FPGA(Field Programmable Gate Array), and 384-MB SDRAM(Synchronous Dynamic Random Access Memory) are included in the DSP board. DSP board manages entire electronics system, generates digital clock patterns and communicates with a PC using USB 2.0 interface. The clock patterns are downloaded from a PC and stored on the FPGA. UART is used for the communication with peripherals. Video board has 4 channel ADC which converts video signal into 16-bit digital numbers. Two video boards are installed on the controller for ALADDIN array. The Bias board provides 16 dc bias voltages and the Clock board has 15 clock channels. We have also coded a DSP firmware and a test version of control software in C-language. The controller is flexible enough to operate a wide range of IR array and CCD. Operational tests of the controller have been successfully finished using a test ROIC (Read-Out Integrated Circuit).

• Korean Journal of Materials Research
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• v.3 no.5
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• pp.459-465
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• 1993

By making the inter-metal PECVD $SiO_2$ as a Si rich oxide under the SOG, the hydrogen and water related diffusants could be captured a t SI dangling bonds. This gettering process was known to prevent the device characteristics degradations related to the H, $H_20$. The basic characteristics of Si rich oxide have been studied according to changing high/low frequency power and $SiH_4/N_2O$ gas flow ratio in PECVD. As increase in low frequency power, deposition rate decreased but K.I. and compressive stress increased. Decrease of the water peaks of FTIR spectra at the wave number range of 3300~3800$\textrm{cm}^{-1}$' also indicated that intensty the films were densified. As increase in SiH, gas flow rate, deposition rate, R.I. and etch rate increased while compressive stress decreased. F'TIK spectra showed that peak intensity corresponding to Si-0-Si stretching vibration decreased and shifted to the lower wave numbers. But AES showed that Si dangl~ng bonds were increased as a result of lower Si:O(l: 1.23) ratlo inthe Si rich oxide as compared to Si : O(1 : 1.98) ratio of usual oxide.

• Journal of Elementary Mathematics Education in Korea
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• v.13 no.2
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• pp.193-210
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• 2009

This research were to develop and apply an educational program for 6th grade students in mathematics by using level orientated teaching method and to make an analysis of their effects on students' mathematics learning achievements and mathematical disposition. Those purposes is following: First, we develop the level orientated teaching method that fits to the low level and high level students and analyze the effect on students' mathematics learning achievements. Second, we analyze the effect on students' mathematical disposition by using level orientated teaching method. The biggest problem of applying level orientated teaching method is that all the groups should do the meaningful activity while just one group is on process. So we tried to keep the proposition that level orientated teaching method should be helpful to both high and low level students. The duration of the research was about 8 weeks from march 2 to may 22 and the level orientated mathematics program consists in lesson 1 "a fraction and a decimal" to lesson 3 "The range of numbers". The results of this study are as follows : First, there was significant effect to the students, develop level orientated mathematics program and using that program. Second, there was an affirmative effect to the students about mathematical disposition using level orientated mathematics program. To sum up conclusion of this study, the level orientated mathematics program has an affirmative effect on mathematics learning achievements and mathematical disposition. We expect further research about level orientated teaching method and use effective level orientated teaching method widely.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.4
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• pp.145-152
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• 2023

The average Nusselt numbers in the source and crystal region for the variation of thermal Grashof number (Gr_t) in the range of 2.31 × 10⁴ ≤ Gr_t ≤ 4.68 × 10⁴ are obtained through numerical simulations. It is shown the average Nusselt number in the crystal region is more than twice as large as the average Nusselt number in the source region. The average Nusselt number in the source region shows an increasing tendency with increasing the thermal Grashof number, Gr_t, while the average Nusselt number in the crystal region shows a decreasing tendency with increasing thermal Grashof number, Gr_t. For the variation of the solutal Grashof number (Gr_s) in the ran ge of 3.28 × 10⁵ ≤ Gr_s ≤ 4.43 × 10⁵, the average Sherwood number in the source region and crystal region tends to decrease as the solutal Grashof number, Gr_s increases. The average Sherwood number in the crystal region is about four times greater than the average Sherwood number in the source region.

• Journal of Korea Water Resources Association
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• v.38 no.8 s.157
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• pp.605-616
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• 2005

In this paper, runoff curve numbers (CN's) for a small forested mountainous catchment are estimated using rainfall-runoff data measured at Sulma experimental catchment every 10 minutes and a new guideline for applying the antecedent rainfall conditions (ARC's) for small mountainous watersheds in Korea is proposed. Sulma experimental catchment is a typical natural mountainous basin with $97\%$ of forested land cover and CN's are estimated to be in the range between 51 and 89 with median value of 72. The test hypothesis stating as 1-day ARC is better than 5-day ARC in determining CN's for a small mountainous watershed is shown to be acceptable. Also, linear regression equations for the estimation of CN's for small mountainous catchments are proposed. As there is no significant investigations available on CN's for small mountainous catchments, the newly proposed relationships between CN's and ARC may be used as a preliminary guideline to assign CN's for the estimation of floods from rainfall data on mountainous regions.

• Journal of the Korean Society for information Management
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• v.40 no.1
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• pp.121-148
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• 2023

The purpose of this study is to propose a scholarly paper recommendation system based on metadata attribute similarity with excellent performance. This study suggests a scholarly paper recommendation method that combines techniques from two sub-fields of Library and Information Science, namely metadata use in Information Organization and co-citation analysis, author bibliographic coupling, co-occurrence frequency, and cosine similarity in Bibliometrics. To conduct experiments, a total of 9,643 paper metadata related to "inequality" and "divide" were collected and refined to derive relative coordinate values between author, keyword, and title attributes using cosine similarity. The study then conducted experiments to select weight conditions and dimension numbers that resulted in a good performance. The results were presented and evaluated by users, and based on this, the study conducted discussions centered on the research questions through reference node and recommendation combination characteristic analysis, conjoint analysis, and results from comparative analysis. Overall, the study showed that the performance was excellent when author-related attributes were used alone or in combination with title-related attributes. If the technique proposed in this study is utilized and a wide range of samples are secured, it could help improve the performance of recommendation techniques not only in the field of literature recommendation in information services but also in various other fields in society.