• Journal of the Korea Society of Computer and Information
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• v.25 no.10
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• pp.261-268
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• 2020

In this paper, we propose an effective software education model for youths with disability. This software education model consists of a four-step process. In the first step, it draws the education curriculum of the software education for different types of disabled youths based on the results of comparative analysis of software education field in special education curriculum. In the second step, it suggests achievement standards for effective software education for the disabled students by classifying students with intellectual disabilities and visual, hearing, and physical disabilities without any multiple disabilities. In the third step, the study developed a modular textbook comprised of unplugged activities using coding robot Albert, physical computing, and block/text coding with the reflection of the characteristic of each type of disability. In the fourth step, it applied the textbook to the school field and educated disabled students focusing on experience to allow them to think logically and by stages about different problems they face in daily lives. In addition, by analyzing the results of youths' performance evaluation and surveys, it was shown that 82.3% of developmental disabilities, 78.8% of visual impairments, 90.9% of hearing impairments, and 78.8% of physically disabilities achieved achievements above the "medium" level. These results prove that the software education model for youths with disabilities proposed in this paper is very effective in improving computational chinking of youths with disabilities.

• Journal of the Korea Society for Simulation
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• v.29 no.1
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• pp.23-30
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• 2020

In this paper, we theoretically examine the characteristics of an Artificial Magnetic Conductor (AMC) constructed of a perfect electric conductor and a normal material having permittivity ε_r, permeability μ_r, and thickness L. First, we derived rigorous equations to describe the infinite AMC structure. Then, we studied how the AMC's characteristics are affected by changes in ε_r, μ_r and L. The operating center frequency exhibiting a 0° reflection coefficient phase occurs when L is one quarter of a guide wavelength. Therefore, the AMC thickness can be reduced by using a material having a high product of ε_r and μ_r. As the ratio μ_r/ε_r increases, the bandwidth of the AMC increases (maximum value: 200 %), and its operating frequency decreases. We also find out he bandwidth of the AMC is improved by introducing a loss in the material. To validate the AMC, we design a dipole antenna on the AMC and demonstrate a relationship between AMC phase and dipole antenna's operating frequency by investigating the dipole on the AMC with different pairs of ε_r and μ_r.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.5
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• pp.353-362
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• 2016

Thermal barrier coating (TBC) is an essential element consisting of a super-alloy base and ceramic coating designed to achieve long operational time under a high temperature and pressure environment. However, the top coat of TBC can be delaminated at certain temperatures with long operation time. As the delamination of TBC is directly related to the blade damage, the coupling status of the TBC should be assured for reliable operation. Conventional studies of nondestructive evaluation have been made for detecting generation of thermally grown oxide (TGO) or qualitatively evaluating delamination in TBC. In this study, the ultrasonic C-scan method was developed to obtain the damage map inside TBC by estimating the delamination in a quantitative way. All specimens were isothermally degraded at $1,100^{\circ}C$ with different time, having different partial delamination area. To detect partial delamination in TBC, the C-scan was performed by a single transducer using pulse-echo method with normal incidence. Partial delamination coefficients of 1 mm to 6 mm were derived by the proportion of the surface reflection signal and flaw signal which were theoretical signals using Rogers-Van Buren and Kim's equations. Using the partial delamination coefficients, the partial delamination maps were obtained. Regardless of the partial delamination coefficient, partial delamination area was increased when degradation time was increased in TBC. In addition, a decrease in partial delamination area in each TBC specimen was observed when the partial delamination coefficient was increased. From the portion of the partial delamination maps, the criterion for delamination was derived.

• Journal of Science Education
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• v.33 no.2
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• pp.353-364
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• 2009

The purpose of this study was to develop 'the problem situations' for the Problem Based Learning(PBL) and to examine it's effects on the science achievement and the attitude towards science learning. Also the students' perception on the PBL model was examined. The topics of the problem situations developed were 'the future energy for reducing the green house effect' and 'the Indonesian forest fire and the El Nino'. The coaching strategies for the PBL were designed and implemented to 10th grade high school students in the science classes, the results are follows; First, the science achievement of the group of PBL is significantly higher than those of group of traditional teaching. Second, the scores of the test of attitude toward science learning of the group of PBL is significantly higher than those of group of traditional teaching. Third, the students' perception of the PBL was positive. Many students have interests and motivations in PBL, some students have difficulties in learning on the PBL. In the students' personal reflection notes the step of a problem statement is the hardest one of the PBL model. Therefore, this study suggests that developing the problem situations based on real context is of great importance for implementing a problem based learning model continuously.

• Journal of Korea Port Economic Association
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• v.31 no.4
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• pp.1-15
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• 2015

During global recessions, such as the 2008 financial crisis, Korean shipping companies have been undergoing a liquidity crisis that is comparably worse than other shipping companies worldwide. One of the reasons behind this repetitive vicious cycle can be the lack of ability to foresee the future by analyzing and understanding the volatile shipping market. Traditionally, in order to assimilate the shipping market, larger Korean shipping companies have been purchasing market reports published by Europe-based research companies and shipping brokers, leading to a digital divide by company size. To resolve this issue, the Maritime Exchange Information Center (MEIC) has been publishing shipping market reports that include essential shipping information such as freight rates by different routes; commodity trends for iron ore, grain, and coal; ship-building trends for new-building, second-hand, and demolition markets; as well as bunker price and port congestion. This research was conducted to analyze the effectiveness of four variables-information usefulness, market reflection, information composition, and latest information-on information satisfaction. If the information satisfaction was found to be adequate, the analysis of actual proof was used to determine if the customers would be willing to purchase MEIC's report when it is chargeable. All the four variables were found to have positive effects on information satisfaction. In particular, latest information was found to directly affect the intention to purchase. Furthermore, high information satisfaction was related to the intention to purchase.

• Journal of the Korean Geotechnical Society
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• v.31 no.11
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• pp.41-48
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• 2015

An investigation of a void and a loose layer of the ground is essential in order to prevent the losses of life and properties caused by subsidence and sinkage of the ground. Recently, studies on the ground penetrating radar survey have been actively conducted in order to estimate the void and the loose layer of the ground. However, an error can be committed by contrarily predicting a dense ground and a loose layer because the ground penetrating radar estimates an interface depth between geo-materials that have different electrical impedances. In this study, a loose ground depth is estimated using the characteristics of the reflected electromagnetic wave obtained from the ground penetrating radar survey. To gather the signals according to the loose ground depths, the ground penetrating radar survey is conducted on a field which underwent a huge ground settlement. In addition, the dynamic cone penetration test is performed to verify the result of the loose ground depth estimation from the ground penetrating radar survey. From the analysis of the reflection characteristics of the electromagnetic wave, a phase of an electromagnetic wave reflected from a denser soil layer is found to be identical with that of the first measured signal. On the other hand, a phase of an electromagnetic wave reflected from the loose soil layer is found to be opposed to that of the first detected signal. The comparison between the dynamic cone penetration index and electromagnetic signals by the ground penetrating radar shows that the estimated depth of the loose or dense layer is perfectly matched with a high reliability. The ground penetrating radar survey and the signal analysis performed in this study can be used not only for the survey of interface depth between the discontinuity layers but also for the estimation of the loose layer.

• The Korean Journal of Ecology
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• v.25 no.5
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• pp.335-339
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• 2002

Concentrations of Fe, Zn, Mn, Cd and Pb were determined in the tissues of sixty adult pigeons collected at six colonies in Korea, and examined correlations between elements, and between tissues in feral pigeons. As the results, we found many significant correlations between elements, and between tissues in them, A negative correlation between Cd and Fe concentrations was observed in the kidney, Cd depresses the absorption of Fe from the intestine and, in this way, affects the levels of Fe in particular tissues. This tendency could be expressed in terms of lower hemoglobin and hematocrit values because hematocrit is one of the most sensitive indicators of Cd intoxication. Zn concentrations are strongly associated with higher Cd levels in the kidney and liver. This is thought to be a reflection of the interaction known to occur between these two metals. Zn induction has been shown to antagonize a number of toxic effects of Cd. A positive correlation between Pb and Fe concentrations was detected in the livers at the Busan colony with relatively high Pb and Fe concentrations. Pb has been shown to co-accumulate with Fe in the liver by inhibiting the heme synthesis. Significant correlations, especially in toxic elements, Pb and Cd, were observed for many pairs of tissues. We suggest that these correlations between elements, and between tissues should be considered in biomonitoring for heavy metal pollution.

• Journal of the Korean earth science society
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• v.38 no.7
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• pp.535-545
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• 2017

Maritime accidents around the Korean Peninsula are increasing, and the ship detection research using remote sensing data is consequently becoming increasingly important. This study presented a new ship detection algorithm using hyperspectral images that provide the spectral information of several hundred channels in the ship detection field, which depends on high resolution optical imagery. We applied a spectral matching algorithm between the reflection spectrum of the ship deck obtained from two field observations and the ship and seawater spectrum of the hyperspectral sensor of an airborne visible/infrared imaging spectrometer. A total of five detection algorithms were used, namely spectral distance similarity (SDS), spectral correlation similarity (SCS), spectral similarity value (SSV), spectral angle mapper (SAM), and spectral information divergence (SID). SDS showed an error in the detection of seawater inside the ship, and SAM showed a clear classification result with a difference between ship and seawater of approximately 1.8 times. Additionally, the present study classified the vessels included in hyperspectral images by presenting the adaptive thresholds of each technique. As a result, SAM and SID showed superior ship detection abilities compared to those of other detection algorithms.

• The Korean Journal of Financial Management
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• v.25 no.2
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• pp.1-31
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• 2008

Before the financial crisis in 1997, Korean bond markets had been those of corporate bonds with relatively high market yield. During the period, most of major institutional investors tend to utilize passive strategies such as buying and holding. After the crisis, however, they could not help choosing active bond management strategies because of lowed yield level and intensified competition among the financial institutions. This study is forced on the yield curve, which is the reflection of all information on the bond investment environments. The study also make analysis on the major economic and securities market factors and its structural relationship with the shape of the curve such as level, curvature and slope. For these purposes, an empirical model based on the Nelson-Siegel Model is estimated with the data during $1999{\sim}2006$. Out-of-sample forecasting is also made to test the usefulness of the estimated model. In addition, the dependent variables which are the estimates of level and slope are estimated on the macro variables and securities market variables. VAR and SUR models are used for the estimation. Estimation results show that level and slope of the yield curve are influenced by the target call rate change, exchange rate change rate, inflation rate. These results provide practical implications for the active managements in the overall treasury bond markets.

• Journal of The Korean Association For Science Education
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• v.33 no.1
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• pp.63-78
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• 2013

Purposes of this study were to explore the process of experience that science teachers go through when participating in peer coaching meetings to improve teaching ability and to find out factors that affect each process of experience. The data were collected through recording of peer coaching meetings, videotapes of science class, and interviews. All the data were analyzed after transcription. The results of the study showed that even though Teacher K broke the ice and formed consensus among the peers by developing Content Representation (CoRe) at the beginning of the meetings, he became self-defensive rather than receptive of peers' opinions on the recorded class at the discussion session. But as the peer coaching went on, he realized that peer coaching was not about evaluation but rather on improving his teaching ability. In turn, he was able to look at his teaching in a more objective point of view and accepted suggestions from peer coaching discussion. The self-reflection of Teacher K acted as the key factor in the efforts to improve his teaching ability. He sought the concrete alternatives through the class analysis with fellow teachers and showed major changes in his teaching practice from the language habits, pronunciation, and speed of his speech to the interaction with students and class design. However, there was little change in knowledge of curriculum and assessment due to his strong orientation to improve students' grades as an academic high school teacher. Likewise, it was found that while peer coaching exert a strong influence on instructional methods and strategies of Teacher K, his strong orientation to improve students' grades hinders a balanced development of subcomponents of PCK.