• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.38-44
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• 2020

Surface texturing of micro-dimples has been used in many manufacturing industries to reduce friction between two sliding contacted surfaces. Surface texturing decreases the frictional force owing to minimizing of the sliding contact area. In this paper, micro-dimples have been fabricated on an Al6061-T6 surface using a two-frequency elliptical vibration texturing (TFEVT) method. A high-frequency of 18 kHz and low-frequency of 250 Hz were applied to an elliptically-vibrated tool holder. The Stribeck curve was plotted to analyze the friction coefficient trends. Furthermore, the representative wetting index, such as the water contact angle (WCA), was measured by considering the friction coefficient. WCA is associated with micro-dimple density and associated parameters. Consequently, the dimpled surfaces with a low friction coefficient exhibited a relatively high WCA in the feed direction. According to the Stribeck curve, the dimpled surfaces demonstrate superior friction performance for mixed-film lubrication compared to the non-textured surface.

• Korean Journal of Pharmacognosy
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• v.40 no.2
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• pp.89-98
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• 2009

The toxicity of aristolochic acid (ArA) has attracted considerable attention since the case of nephropathy regarding diet pill preparations was reported. The present study was performed to determine the reproductive toxicity of ArA in female SD rats. ArA was administered orally to female rats at 2, 8 or 16 mg/kg b.w./day and the females were mated with untreated males and their reproductive status was determined. ArA is well known as PLA2 inhibitor, toxic effects of such a relationship are not yet clear, and in vivo study on this matter are scarce. For this study, ArA was administered to pregnant rats at 10 or 20 mg/kg b.w./day, because premating treatments were not conducted. Administration of 20 mg/kg b.w./day caused infertility or abortion. In ArA-treated groups, PGF2a productions were inhibited and apoptosis were suppressed. Collectively, this study may help to further define the roles of sPLA2 in reproductive organs and to determine the toxic mechanisms of ArA.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.6
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• pp.545-555
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• 1991

In this paper, We discuss optical implementation of new optical adaptive patern recognition system based on single layer perception with learning capability and associative memory model having error corrective capability. The single layer perceptron is optically implemented by using 2 D LCTV spatial light modulators through the nonlinear quantization and polarization encoding methods, and 2 D hopfield associative memory is also implemented by using multifocus holographic lens. From some experimental results on classfication of Arabic numbers into even & edd numbers, it is shown that the proposed system can classify the patterns to the right classes correctly even for the partial and erronenous input patterns. Accordingly, the proposed optical adaptive pattern recognition system can be suggested for practical application in the fields of image processing and pattern recognition.

• Journal of Engineering Education Research
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• v.24 no.6
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• pp.40-49
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• 2021

The purpose of this study is to explore the possibility of changing students' learning styles and preferred teaching styles after applying the flipped learning method to engineering education. In order to achieve the purpose of this study, literature review and survey study were conducted. The subject of application of the flipped learning method is the 'Creative Problem Solving Methodology' class, which is one of the specialized liberal arts subjects operated for students of the college of engineering at D university in Gyeonggi-do. For the survey study, a tool adapted to the domestic conditions of Kolb's learning style test tool and Felder & Silverman's preferred teaching style test tool was used. In addition, pre- and post-tests were conducted to measure changes in the learning styles and preferred teaching styles. As a result of applying the flipped learning method for one semester, the learning style showed a tendency to change from an accommodative to a divergent learner. In addition, in the case of the preferred teaching styles, it was confirmed that there were statistically significant changes in the organization and the area of participation. Based on these findings, a proposal for a follow-up study was presented.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.2
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• pp.23-31
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• 2021

Surface texturing is a promising route to reduce the friction forces between two surfaces in sliding contact. To this end, the fabrication of micro dimples is one of the most widely used surface texturing methods. According to published results, textured surfaces with elliptical micro dimples offer the best friction performance. Therefore, we fabricated elliptical micro dimples on carbon steel (SM45C) by using dual frequency vibration assisted machining. High and low frequencies of 16.3 kHz and 230 Hz were applied to the 3D resonant elliptical vibrator. The 3D resonant elliptical vibrator with a triangular cubic boron nitride insert was assembled on a computer numerically controlled turning lathe. Oval micro dimples of various profiles were manufactured on carbon steel. In terms of the profile of the elliptical micro dimples, the experimental results indicated that the average micro dimple width and depth were 112 ㎛ and 7.7 ㎛. These dimensions are closely related to the cutting conditions and can be easily controlled.

• Journal of Engineering Education Research
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• v.24 no.2
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• pp.41-50
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• 2021

This study was conducted with the aim of exploring ways to more effectively manage related courses by checking the educational effects of the operation of engineering liberal arts courses operated for the development of communication skills of engineering students by detailed factors of communication skills. To achieve the purpose of the study, literature review and survey methodologies were used. A survey was conducted before and after class targeting four class students of the engineering college of D University in Gyeonggi-do. As a result of comparing the results of the pre-test before class through this class and the results of the post-test conducted at the end of the class, it was confirmed that speaking ability, reading ability, and communication ability were improved at a statistically significant level. In addition, as a result of analyzing differences in communication competencies for each individual variable, it was found that there were statistically significant differences according to gender, students' major field, and grade. Based on such research results, several educational proposals were presented to increase the effectiveness of the management of courses operated to develop communication skills.

• Journal of English Language & Literature
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• v.58 no.4
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• pp.611-632
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• 2012

Beckett's life-long struggling with death may be illuminated in terms of the Western tradition of thanatology as well as Philippe Ariès's anthropological classification of death. Among the Western tradition, Beckett's oeuvre incarnates memento mori, timor mori, nihilism, theatrum mundi, life as afterlife, and the transsubstantiation of the self. Among the five views of death Ariès suggests, Beckett appears to foreground the death of the self and the invisible dirty death. In a world devoid of transcendental Signified, Beckett's resident is "a poor player/That struts and frets his hour upon the stage." Our contemporary vision of death is dominated by the dirty death and timor mori resurrected from the cultural icon of danse macabre in the late Mediaeval age as vividly dramatized in W;t by Margaret Edson. Beckett stands in no man's land: Lucky complains of divine aphathia as well as scopes at the possibility of God's existence like Hamm. Beckett's way of getting out of the dilemma is laughing a mirthless and dianoetic laugher. To bourgeois class who shudder at the sight of Grim Death after forgettable years of indulgence and addiction to capitalist consumption, Beckett seems to preach, your life is a death-in-life, you are not born yet until you are baptized with existential awakening as Gregor Samsa in Kafka's Verwandlung, or Tolstoy in Confession.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.339-341
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• 2023

This paper presents a multithread and efficient cryptographic hardware access (MECHA) for efficient and fast cryptographic operations that eliminates the need for context switching. Utilizing a UNIX domain socket, MECHA manages multiple requests from multiple applications simultaneously, resulting in faster processing and improved efficiency. We comprise several key components, including the Server thread, Client thread, Transceiver thread, and a pair of Sender and Receiver queues. MECHA design is portable and can be used with any communication protocol, with experimental results demonstrating a 83% increase in the speed of concurrent cryptographic requests compared to conventional interface design. MECHA architecture has significant potential in the field of secure communication applications ranging from cloud computing to the IoT, offering a faster and more efficient solution for managing multiple cryptographic operation requests concurrently.

• Asia-Pacific Journal of Business
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• v.14 no.4
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• pp.331-342
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• 2023

Purpose - This study aims to develop a valid and appropriate method for measuring the economic value of intangible cultural resources. Design/methodology/approach - Building upon the concepts explored in many studies on the total value regulation of public goods or environmental goods, which are non-market value commodities, with a focus on the intangible cultural property Arirang, this study aims to formulate a new economic value concept for cultural resources that contributes to the overall economic total value, including non-use value. Based on this foundation, the study aim to identify and apply the most efficient model(CVM) among economic value measurement methods, as suggested by Tietenberg (2003). Findings - This involves estimating economic value through consumer behavior, encompassing the use or experience of cultural resources, as well as utilizing statements to estimate economic methods through consumer surveys. Only by presenting individual resource economic values of cultural resources in objective figures can a foundation be established for creating budgets and organizational structures to promote projects and policies. Research implications or Originality - Appropriate decisions can then be made by comparing these values with the expected costs in the management and planning process.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.175-178
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• 2024

IoT is becoming more and more popular, along with the massive availability of cheap and easy-to-use IoT devices. One protocol that is often used in IoT devices is the Message Queuing Telemetry Transport (MQTT) protocol. By default, the MQTT protocol does not activate encrypted data security features. This MQTT default feature makes the transmitted and received message data vulnerable to attacks, such as eavesdropping. Therefore, this paper will design and implement encrypted data security using the lightweight cryptography algorithm. The focus of this paper will be on securing MQTT message data at the application layer. We propose a method for encrypting specific MQTT message fields while maintaining compatibility with the protocol's functionalities. The paper then analyzes the timing performance of the MQTT-LEA implementation on the Raspberry Pi 3+. Our findings demonstrate the feasibility of using LEA at the application layer to secure MQTT message communication on resource-constrained devices.