• Ceramist
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• v.22 no.1
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• pp.36-55
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• 2019

Atomically thin two-dimensional (2D) nanomaterials, including transition metal dichalcogenides (TMDs), graphene, boron nitride, and black phosphorus, have opened up new opportunities for the next generation optoelectronics owing to their unique properties such as high absorbance coefficient, high carrier mobility, tunable band gap, strong light-matter interaction, and flexibility. In this review, photodetectors based on 2D nanomaterials are classified with respect to critical element technology (e.g., active channel, contact, interface, and passivation). We discuss key ideas for improving the performance of the 2D photodetectors. In addition, figure-of-merits (responsivity, detectivity, response speed, and wavelength spectrum range) are compared to evaluate the performance of diverse 2D photodetectors. In order to achieve highly reliable 2D photodetectors, in-depth studies on material synthesis, device structure, and integration process are still essential. We hope that this review article is able to render the inspiration for the breakthrough of the 2D photodetector research field.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.168-173
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• 2002

The durability test, along with the crashworthiness test, requires the most time and expense in the vehicle development process. The durability design using CAE tools reduces the time required for both the durability test and actual vehicle production. Existing dynamic stress analyses designed fir the analysis of vehicle fatigue mainly calculate the dynamic stress history and fatigue after performing dynamic analysis and stress analysis with relevant software applications and then superpositioning the dynamic load history and stress influence coefficient at each joint. This approach is a complex process, taking into account the flexibility of the parts. It is, however, incapable of giving accurate consideration to the contacts between components, the non-linearity of materials, and tire-road surface interactions. This approach also requires that the analysts have an expertise in software applications of various kinds or an expert in each area must perform the analysis. This requires as a great deal of manpower and time. In order to complement the existing approaches for dynamic stress analysis, this study aims at the following: (1) to suggest the simple and accurate analysis technique which is capable of producing all the possible necessary results; (2) to reduce dramatically the time and manpower needed to construct a model designed to analyze dynamics, quasi-static stress, and fatigue; and (3) to enable an accurate analysis of fatigue by improving the accuracy of dynamic stress. we verify the presented analysis method through durability evaluation of the knuckle of passenger car.

• Journal of Families and Better Life
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• v.34 no.5
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• pp.69-82
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• 2016

The purpose of this study was to explore mediating effects of interpersonal competence, gratitude disposition between childcare teachers positive psychological capital and happiness. The subjects of the study were a total 231 Childcare in Seoul. The statistics program used to achieve the purpose was SPSS/PC+18.0. The statistics methods applied were pearson correlation coefficient, simple linear regression, and multiple linear regression. The major results of this study were summarized as follows: First, Positive psychological capital and interpersonal competence, and gratitude disposition from happiness was found to be positively correlated. Second, interpersonal competence had an affect on childcare teachers happiness. These effects are mediated in part by the control interpersonal competence showed. Third, gratitude disposition affects childcare teachers happiness. These effects are mediated in part by the gratitude disposition showed. These results suggest that dispositional gratitude and cognitive flexibility play an important role in the development of happiness for childcare teachers.

• Journal of the Korean Home Economics Association
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• v.42 no.3
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• pp.179-193
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• 2004

The purpose of this study was to develop the Family System Diagnosis Scale and to examine its reliability and validity. The subscales of the questionnaire included scores on seven constructs. In order to define constructs accurately, a careful review of Minuchin's writings, the writings of other family therapists, and relevant articles on family interaction was undertaken. A pool of 150 items was given to eight family counselors along with a description of Minuchin' s concepts. The counselors were asked to choose the category each statement fit and to rate the degree of fit using the 3-point scale. Using exploratory factor analysis, confirmatory factor analysis and Linear Structural Relationship(LISREL), six subdimensions of individuation and 55 items of FSDS were identified; enmeshmen disengagement(16 items), parent coalition generational coalition(6 items), flexibility rigidity(5 items), spouse conflict resolved unresolved(8 items), mother-child cohesion estrangement(10 items), father-child cohesion estrangement(10 items). 356 adolescents(ages 13∼18), 356 fathers, 356 mothers in Seoul, Busan, Dague, Incheun, Dajeun, Ulsan, and Kwangju were completed the Family System Diagnosis Scale(FSDS). The reliability of the scale was calculated by Cronbach's a Coefficient and the total a = .94 and the calculation for each factor was .87, .60, .77, .80 and .79 respectively.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.400-405
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• 2018

This paper presents a compact ultra-wideband (UWB) flexible monopole antenna design on a paper substrate. The proposed antenna is made of iterations of a circular slot inside an octagonal metallic patch. This fractal-based geometry has been deployed to achieve compactness along with improved bandwidth, measured reflection coefficient -10 dB bandwidth ranging from 2.7 to 15.8 GHz. The overall size of the antenna is $26mm{\times}19mm{\times}0.5mm$, which makes it a compact one. The substrate used is paper and the main features like environment friendly, flexibility, green electronics applications and low cost of fabrication are the key factors for the proposed antenna. The aforementioned UWB prototype is suitable for many wireless communication systems such as WiMAX, WiFi, RFID and WSN applications. Antenna has been tested for the effect of bending by placing it over a curved surface of a very small radius of 10 mm.

• 한국기계연구소 소보
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• s.13
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• pp.143-161
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• 1984

The mass balancing of rotors is an integral part of the study practice of the rotor dynamics. Any machine with rotating components is considered to be rotating machine. The part of a rotating machine that rotates in normal operation is generally reffered to as a rotor. A rotor is flexible if it deforms when the machine is operating at any speed up to its maximum design speed. Otherwise, the rotor is rigid. The general Purpose of the study of rotor dynamics is to increase understanding of rotor vibration phenomena and thus provide a means for controlling or eliminating these vitrations. As the efficiency of rotating machinery has been increased through reduced weight and increased speed, which implies increasement of rotor flexibility, the control of rotor vibration has become essential. Thus, the study and practice of rotor dynamaics has taken on an increasingly important role in recent years. Therefore many workers have studied about this and introduced a few balancing methods of flexible rotor, which can be classified mainly in following four sorts, 1. Polar plotting methed 2. Modal balancing method 3. Influence coefficient method 4. Unified balancing approach In this paper practical theories of rotor dynamics related to flexible rotor balancing have been reviewed and confirmed the calculation results of flexible balancing of typical rotor, as an example, respectively

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.1 s.160
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• pp.77-84
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• 2007

The purpose of this study was to investigate and to compare the performances of silicone laminated materials sold for swimming cap in market, to get the basic data for product development. We selected 4 specimens and tested their air permeability, waterproofness and breathability. We also tested the physical and mechanical properties of the specimens using KES system. Silicone-laminated material was not bursted on high hydraulic pressure since silicone membrane gave waterproofness while PU/Polyester substrate gave elasticity. It didn't have air permeability and breathability at all. Any toxic materials such as Formaldehyde, Deldrin, PCP, Amin, TDBPP were not detected in silicone-laminated material and other materials. Silicone-laminated material had higher stretchability with the low force but it had lower elastic recovery and shape stability comparing to PU laminated material. It had lower flexibility than PU laminated material. It had lower unrecoverable amount in shearing direction. Friction coefficient was higher in silicone-laminated material than PU laminated material due to its surface stickiness. It was compressed easily and its compression resiliency was higher with compared to PU laminated material.

• Journal of the Institute of Convergence Signal Processing
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• v.4 no.3
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• pp.55-60
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• 2003

In the controller design of position or velocity control system, the flexibility of the mechanical system is always the limiting factor to the higher performance. Most mechanical systems coupled with rotary shaft are 2-Inertia systems which are consist of motor and load inertia. These inertias make a torsion In rotary shaft and cause torsional vibration. To suppress vibration, various control strategies have been proposed mainly for controlling 2-inertia system. In this paper, a speed controller design for a 2-inertia system composed of voltage controlled DC motor and load inertia is made by using CDM(coefficient diagram method). First, the 2-inertia system model is derived. Then the CDM is used to design the proper controller. A validity of this approach is confirmed by simulation and experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.473-476
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• 2003

This paper shows necessity of encapsulation layer to maximite flexibility of brittle indium-tin-oxide (ITO) on polymer substrates. And, Young's modulus (E) of encapsulation layer have an significant effect on external bending stress and the coefficient of thermal expansion (CTE) of that have a significant effect on internal thermal stress. To compare magnitude of total mechanical stress including both bending stress and thermal stress, the mechanical stress of triple-layer structure (substrate / ITO / encapsulation layer or substrate / buffer layer / ITO) can be quantified and numerically analyzed through the farthest cracked island position. As a result, it should be noted that multi-layer structures with more elastic encapsulation material have small mechanical stress compared to that of buffer and encapsulation structure of large Young's modulus material when they were externally bent.

• Korean Journal of Materials Research
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• v.32 no.2
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• pp.107-113
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• 2022

Fibrous supercapacitors (FSs), owing to their high power density, good safety characteristic, and high flexibility, have recently been in the spotlight as energy storage devices for wearable electronics. However, despite these advantages, FCs face many challenges related to their active material of carbon fiber (CF). CF has low surface area and poor wettability between electrode and electrolyte, which result in low capacitance and poor long-term stability at high current densities. To overcome these limits, fibrous supercapacitors made using surface-activated CF (FS-SACF) are here suggested; these materials have improved specific surface area and better wettability, obtained by introducing porous structure and oxygen-containing functional groups on the CF surface, respectively, through surface engineering. The FS-SACF shows an improved ion diffusion coefficient and better electrochemical performance, including high specific capacity of 223.6 mF cm^-2 at current density of 10 ㎂ cm^-2, high-rate performance of 171.2 mF cm^-2 at current density of 50.0 ㎂ cm^-2, and remarkable, ultrafast cycling stability (96.2 % after 1,000 cycles at current density of 250.0 ㎂ cm^-2). The excellent electrochemical performance is definitely due to the effects of surface functionalization on CF, leading to improved specific surface area and superior ion diffusion capability.