• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5C
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• pp.393-402
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• 2012

In this study, we propose a signal processing algorithm to measure the arousal level of a human subject using a PPG(Photoplethysmography) sensor. From the measured PPG signals, the arousal level is determined by PPI(Pulse to Pulse Interval) and discrete-time signal processing. We ran psychophysical experiments displaying visual stimuli on TV display while measuring PPG signal from a finger, where the nature landscape scenes were used for restorative effect, and the urban environments were used to stimulate the stress. However, the measured PPG signals may include noise due to subject movement and measurement error, which results in incorrect detections. In this paper, to mitigate the noise impact on stimulus detection, we propose a detecting algorithm using digital signal processing methods and statistics of measured signals. A filter is adopted to remove a high frequency noise and adaptively designed taking into account the statistics of the measured PPG signals. Moreover we employ a hysteresis method to reduce the distortion of PPI in decision of emotional. Via experiment, we show that the proposed scheme reduces signal noise and improves stimulus detection.

• Journal of Korean Society of Forest Science
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• v.99 no.4
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• pp.517-527
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• 2010

The purpose of this study was to investigate the causal relationship among perceived value, satisfaction and revisit intention for visitors of the Korea National Arboretum. Three hundred respondents were selected by quota sampling, and well-known measurement scales utilized in marketing field were adopted in order to measure three variables with some modification to apply for arboretum visitors. Results of structural equation model showed that perceived value affected visitors' satisfaction, which in turn influenced revisit intention. Specifically, "emotional value" had the most significant influence on satisfaction, followed by "value for money" and "novelty value"; however, "social value" was not an influential construct. Based on calibration results, several strategies were suggested for the effective management. Authors advised that (a)improvement of measurement scale of value, (b)inclusion of self-congruity as antecedent variable to satisfaction, (c)changing revisit intention to word-of-mouth communication as a post-purchase behavioral intention, and (d)implementation of market segmentation should be considered for future research.

• The KIPS Transactions:PartB
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• v.18B no.3
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• pp.117-130
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• 2011

The purpose of this study is to produce a better way to detect crossroad accidents, which involves an efficient method to produce background images in consideration of object movement and preserve/demonstrate the candidate accident region. One of the prior studies proposed an employment of traffic signal interval within crossroad to detect accidents on crossroad, but it may cause a failure to detect unwanted accidents if any object is covered on an accident site. This study adopted inverse perspective mapping to control the scale of object, and proposed different ways such as producing robust background images enough to resist surrounding noise, generating candidate accident regions through information on object movement, and by using edge information to preserve and delete the candidate accident region. In order to measure the performance of proposed algorithm, a variety of traffic images were saved and used for experiment (e.g. recorded images on rush hours via DVR installed on crossroad, different accident images recorded in day and night rainy days, and recorded images including surrounding noise of lighting and shades). As a result, it was found that there were all 20 experiment cases of accident detected and actual effective rate of accident detection amounted to 76.9% on average. In addition, the image processing rate ranged from 10~14 frame/sec depending on the area of detection region. Thus, it is concluded that there will be no problem in real-time image processing.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1207-1212
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• 2006

In this study, Chemical Oxygen Demand(COD) which is the measure of organic substances, Total nitrogen(T-N), Total phosphorous(T-P), Fe and Mn were analyzed in the sediments of dam reservoir. The purpose of this study were to understand the relevances among the analytical methods adopted and the applicabilities of those methods. For the determination of COD, Standard Method for the Examination of Marine Environment(SMEME) and Standard Method for the Examination of Sanitary(SMES) was used. Both method had wide dynamic range and the deviations of the values obtained by two methods were small because $KMnO_4$ method closely reflected BOD and organic substances. For the determination of T-N and T-P, Standard Method for the Examination of Food(SMEF) and Standard Method for the Examination of Sanitary(SMES) were used. Two methods for T-N were both the acid-base titration but SMES gave less T-N values than SMEF because of the differences in digestion and distillation steps. Two methods for T-P gave the comparable values after acid digestion of $HNO_3$ and $HClO_4$. The determination of heavy metals as a Fe, Mn was mainly divided to the leaching method and acid digestion method. The values obtained by leaching method were less than those by digestion method. It is thought that the condition of acid digestion was more severe than that of leaching method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8A
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• pp.739-752
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• 2002

Recently, to utilize the limited bandwidth effectively, the concept of partial response (PR) signaling has widely been adopted in both the high-speed data transmission and high-density digital recording/playback systems such as digital microwave, digital subscriber loops, hard disk drives, digital VCR's and digital versatile recordable disks and so on. This paper is concerned with adaptive equalization of partial response channels particularly for the magnetic recording channels. Specifically we study how the PR channel equalizers work for different choices of desired or reference signals used for adjusting the equalizer weights. In doing so, we consider three different configurations that are actually implemented in the commercial products mentioned above. First of all, we show how to compute the theoretical values of the optimum Wiener solutions derived by minimizing the mean-squared error (MSE) at the equalizer output. Noting that this equalizer MSE measure cannot be used to fairly compare the three configurations, we propose to use the data MSE that is computer just before the final detector for the underlying PR system. We also express the data MSE in terms of the channel impulse response values, source data power and additive noise power, thereby making it possible to compare the performance of the configurations under study. The results of extensive computer simulation indicate that our theoretical derivation is correct with high precision. Comparing the three configurations, it also turns out that one of the three configurations needs to be further improved in performance although it has an apparent advantage over the others in terms of memory size when implemented using RAM's for the decision feedback part.

• Asia pacific journal of information systems
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• v.19 no.4
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• pp.149-176
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• 2009

In the recent e-learning environment, avatars are often used to help learners get familiar with the contents, which is ultimately to motivate them to study more. Therefore, it is important to investigate whether avatars have actually the desirable effect on users of e-learning materials. Surprisingly, however, no extensive study has been conducted on this crucial issue Accordingly, main objectives this study are summarized as follows. First, we need to gain better understanding of how much learners' trust towards avatars (termed as "avatar trust") is transferred to learners' trust towards e-learning contents (termed as "contents trust"). Second, we need to investigate how much learners' personal relationships with avatars as well as learning behaviors change depending on avatar types (attractive vs. professional) and contents complexity (easy vs. difficult). As described in the study objectives, in order for us to analyze empirical data more systematically, we classified avatar types into two: "attractive" and "professional;" the contents are categorized as either "easy" or "difficult." Therefore, it is essential for this study to build a prototype e-learning website on which our research purpose can be realized and tested effectively with proper avatar types and e-learning contents. For this purpose, we built a prototype e-learning website, in which avatars are invited from currently working avatar instructors used in real-world e-learning websites, and e-learning contents are adapted from real-world contents about Java programming topic, which have been proved to have shown high quality and reliability. Our research method includes questionnaire survey by inviting a number of valid respondents comprised of office workers who are believed to have high demands for the e-learning contents as well as those who have previous experience with avatar instructors. Respondents were given one of the four e-learning experiment conditions (2 avatar types x 2 contents types) on a random basis. Each experimental e-learning condition is framed to have the same quality but different avatar type and content complexity. Then the respondents are asked to fill out the survey form which has questions about avatar trust, contents trust, personal relationships with avatar, and learning behavior, among others. Regarding the constructs used in research model, we based them rigorously on previous studies. For example, we used six constructs such as behavior to give information (BGI), behavior to obtain information (BOI), need for inclusion wanted, need for control wanted, contents trust, and avatar trust. To measure them, 7-Likert scales were used in the questionnaire. E-learning performance was measured indirectly through two constructs such as BGI and BOI. Six constructs used in the research model were adopted and revised from the FIRO-B model suggested by Schutz. Empirical results are as follows: First, professional avatars are more effective for difficult contents, while attractive avatars were not as effective for easy contents. Second, our study results ascertained that avatar trust transfers to contents trust regardless of avatar types and contents complexity.

• Journal of Navigation and Port Research
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• v.45 no.4
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• pp.224-230
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• 2021

It has been 16 years since the government announced its first Ocean Education Policy in 2005. Although the public consensus on the importance of ocean education has been formed, it is impossible to objectively analyze the impact of the policy on the society or the economy. The aim of this paper was to identify differences in perceptions and behaviors about the ocean between groups participating in ocean education and non-participating groups and to analyze the effectiveness of ocean education by developing measurement indicators for the value that individuals gave to ocean education services. To conduct this study, first, the value of ocean education was defined and value items that could be provided to individuals were classified. Second, to develop indicators that could measure classified value items, a Delphi survey was conducted to collect opinions of various experts. Third, by measuring the content validity ratio (CVR) for each item, final indicators and questionnaire were derived. As a result of Delphi analysis, 18 items with a CVR value of 0.6 or higher were finally adopted out of 32 indicator items. In the cognitive value category, indicators that could identify an individual's level of knowledge of the ocean, change in perception, and problem-solving ability were selected. In the behavioral value category, indicators were expanded to judge changes in attitudes and relationships toward the ocean and responsible behavior in more detail. This study is meaningful in that it provides the basis for directly judging the value of ocean education service provided by the government to the people. Results of such analysis are expected to contribute to securing a stable budget and the justification for expanding human resources in the government's continuous promotion of ocean education policies.

• Journal of the Korean Geotechnical Society
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• v.37 no.10
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• pp.13-25
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• 2021

The most widely used method for determining the blast effects of explosives is the Trauzl test. This test is used to measure the explosive power (strength) of a substance by determining volume increase, which is produced by the detonation of a tested explosive charge in the cavity of a lead block with defined quality and size. In this paper, Trauzl lead block test and High speed 3D-DIC (Digital Image Correlation) system were conducted to evaluate the stemming effect of the blast hole. The effects of stemming materials can be expressed as the expansion of the cavity in a standard lead block through explosion of the explosives. The blasting experiment was conducted with emulsion explosives. The stemming material in the blast hole of lead block, which was adopted in this study, were using sand and stone chips. Results of blasting experiment and numerical analysis showed that the expansion rates of lead block were most affected by stone chips followed by sand. Also, as result of dynamic strain measurement on the lead block surface of High speed 3D-DIC system, the displacement and surface strain on the block were the highest in the experiment case of stone chips stemming.

• Journal of Digital Convergence
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• v.19 no.1
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• pp.401-410
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• 2021

Since the outbreak of Corona 19, Universities and Lifelong Education Center's arts and sports classes are mainly conducted online. Unfortunately, even in dance where practical practice through face-to-face classes is important, the satisfaction of students is falling because of the limitations of online education. Therefore, it is necessary to measure the quality of education service they feel. In addition, since their academic departure is increasing, we intend to comprehensively study user satisfaction, continuous use intention, and academic continuity intention related to online education. This study confirmed the causal relationship between these 4 variables through exploratory factor analysis, reliability analysis, model fit and validity verification, and path analysis. As a result of the study, 3 out of 6 hypotheses were adopted, and the of education service quality had a positive effect on satisfaction and use in online dance education. But there was also a limit that did not affect the intention to continue the study. In order to solve fundamental problems such as academic departure, follow-up studies taking into account more diverse social variables are needed.

• Geophysics and Geophysical Exploration
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• v.24 no.1
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• pp.20-27
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• 2021

Subsurface rock produces heat from the decay of radioactive isotopes in constituent minerals and gamma-ray emissions, of which the magnitude is dominated by the contents of the major radioactive isotopes (e.g., U, Th, and K). The heat production is generally calculated from the rock density and contents of major isotopes, which can be determined by mass spectrometry of drilled core samples or rock fragments. However, such methods are not easily applicable to deep boreholes because core samples recovered from depths of several hundred meters to a few kilometers are rarely available. A geophysical logging technique for boreholes is available where the U, Th, and K contents are measured from the gamma-ray spectrum. However, this technique requires the density to be measured separately, and the measurement depth of the equipment is still limited. As an alternative method, a normal gamma-ray logging tool was adopted to estimate the heat production from the total gamma activity, which is relatively easy to measure. This technical report introduces the development of the proposed method for evaluating the heat production of a granitic rock mass with domestic commercial borehole logging tools, as well as its application to a ~2 km deep borehole for verification.