• Journal of Science Education
• /
• v.42 no.2
• /
• pp.120-131
• /
• 2018

The purpose of this study is to examine the characteristics of science gifted students' understanding of friction acting on a rolling object, and to examine the implications of teaching methods that can be derived from them. For this purpose, 48 students in grade 3 students who take advanced physics classes at the science high school for the gifted were asked to answer three questions about the friction problems. As a result, students' responses were divided into three types: rule, none-rule, and calculation. In addition, students of the rule type have difficulty in reasoning about the friction by using friction rules. We believe that students will be able to reach a deeper understanding of friction if we teach them to correctly infer the direction of friction without using friction rules, along with a strategy to emphasize relative motion in contact.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2009.05a
• /
• pp.59.2-59.2
• /
• 2009

화학보호복은 독성이 있는 화학물질 및 미세분진등에 대해 공기를 차단하며 완전 밀폐형으로 공기호흡기 및 에어라인 같은 호흡보호장치와 함께 착용하여 신체부위를 보호한다. 그 예로 생물/화학보호복은 유독하고 해로운 생물/화학물질로 부터 인체를 보호해준다. 이들 보호복은 다양한 환경이 노출되어 장시간 작업을 위해서 오랜시간 보호성능을 유지해야한다. 특히, 이런 원단의 구성은 플라스틱과 고무류의 다층구조로 구성되어있다. 플라스틱류(폴리에틸렌, PTFE 등)는 표면장력이 너무 낮아 접착하는데 어려운 점이 많이 대두된다. 일반적인 표면처리방법은 크게 물리화학적 방법으로 4가지로 분류한다. 화학적산화, 불꽃처리, 플라즈마처리, UV 방사법 등이 있다. 이들 중에서 가장 간단한 산화처리는 플라즈마처리다. 이처리는 상온/상압하에서 대기 중 또는 가스내에 방전에 의해 플라즈마를 형성하고 이 플라즈마가 대상물의 표면분자와 격렬히 반응하게 하여 표면의 분자구조를 변화시킴에 따라 소수성의 표면에 Carboxyl, hydroxyl과 carbonyl과 같은 친수성으로 변하여 결합능력을 증가 시켜 표면장력을 높여주는 가장 효과적인 방법이다. 플라즈마 표면처리를 하고 나면 육안으로 표면의 변화를 감지할 수 없지만 접착, 잉크, 코팅을 잘 받아들이는 결과를 가져온다. 플라즈마 표면처리의 효과는 주로 부도체의 필름이나 합성수지 계열의 인쇄성과 접착성을 향상시키고자 많이 활용되고 있는 실정이다. 특히, 화학보호복과 같은 플라스틱류인 다양한 고분자 합성수지(Polyethylene, polypropylene, nylon, vinyl, PVC, PET 등)에 적용가능하다. 본 연구에서는 플라즈마처리조건에 영향을 주는 변수들을 고려하여 실험계획법(DOE, RSM)을 이용하여 최적화된 플라즈마 공정을 향상시키고자한다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.12
• /
• pp.1465-1471
• /
• 2013

The electrical and mechanical properties of room temperature vulcanized (RTV) silicone rubber composites are investigated as functions of multi-walled carbon nanotube (CNT), carbon black (CB), and thinner content. The thinner is used to improve the CNT and CB dispersion in the matrix. The electrical and mechanical properties of the composite with CNT are improved when compared to the composite with CB at the same content. As the thinner content is 80 phr, the electric resistance of the composite decreases significantly with the CNT content and shows contact point saturation of CNT at 2.5 phr. As the thinner content increases, the dispersion of conductive particles improves; however, the critical CB content increases because of the reduction in the CB weight ratio. It is believed that an electrode that needs good flexibility and excellent electrical properties can be manufactured when the amount of CNT and CB are increased with the thinner content.

• Journal of Convergence for Information Technology
• /
• v.7 no.2
• /
• pp.25-29
• /
• 2017

The purpose of this study was to investigate the effect of a new designed splint on the hand function. A new design splint that enlarges the area between thumb and index finger was manufactured using 3D printing. After wearing a new splint the patient was possible to open thumb and hold a small object. She showed improvement in overall hand function and could move eight blocks in box and block test. But grasping a cup without a handle has become more difficult than before. Also there is a disadvantage that it could not be fixed by water. This study is meaningful in that it is the first splint application study using 3D printing. In the future, we expect that various patient-specific splints will be developed through 3D printing in the field of occupational therapy.

• Journal of the Korea Convergence Society
• /
• v.10 no.6
• /
• pp.401-409
• /
• 2019

The purpose of this study is to investigate factors affecting the long - term care - related employment intention of nursing students in graduation grade. The study design was a descriptive study. As a result, the average intention of employment at the long - term care institution for the elderly was 2.8. It differed according to the experience of living with the elderly, the degree of interest in the elderly problem, long-term care benefits for the elderly in the family, and the concern of the long - term care insurance system. Therefore, in order to induce nursing college students to work in the long-term care field of elderly people, it is necessary to operate various curriculum and comparative programs that can get interested in the elderly problem. and long-term care insurance.

• Journal of Internet Computing and Services
• /
• v.23 no.2
• /
• pp.87-95
• /
• 2022

Cyber society formed by the development of the Internet is growing rapidly. The Internet is very convenient for our daily life, but it comes with negative aspects including cybercrime and cyberbullying. Recently, there have been incidents that show cyber criminal techniques of adolescents are getting more sophisticated and ferocious. To cope with this crime problem, it is necessary to analyze the causes that affect cyber crime offences among adolescents. There are numerous studies on cybercrime, but less attention has been given to trend analysis. To fill this void, this study examined how the factors that affected the cyber crime offences among adolescents have been changed over time according to transitions in social structure. Implications for future research and policies for adolescents' cyber crime prevention such as time considered response strategies are discussed based on the findings.

• Journal of the Korea Society for Simulation
• /
• v.19 no.2
• /
• pp.99-106
• /
• 2010

In the anti-submarine warfare, a search using HMS is used as a basic strategy. The importance of HMS operation strategy is increasing, but it is hard to develop effective anti-submarine search strategy due to reciprocal actions among sea environments, search patterns, sonar operational tactics, anti-submarine search strategy, etc. In this research, a simulator was invented so as to analyze anti-submarine search patterns used when an HMS-carrying ship searches for submarine in various anti-submarine search environments. The simulator reflects various factors that influence anti-submarine search, and with consideration of search patterns of anti-submarine ships as well as evasive movement of submarines, it can simulate various anti-submarine search operations such as a collaborative anti-submarine operation by a single or multiple forces. Also, the simulator will contribute to developing and improving systematic and efficient HMS operational tactics in anti-submarine warfare.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.2
• /
• pp.58-66
• /
• 2023

In this study, cable tension was measured using the vibration method, and a vision-based system was applied as a sensor to measure the displacement response of a cable in a non-contact method. In the vision-based system, the camera is installed in a location that considers the target structure and the field of view of the camera. However, it can be difficult to recognize the control points required to measure the displacement response of a structure as the target structure and other structures such as vehicles may be included in the image at the intended installation location. In this study, a distorted image including a vehicle shows inaccurate results in image analysis due to the installation position of the vision-based system. Accordingly, the image including the vehicle was eliminated by calculating the similarity between the two images. To verify the validity of the method of estimating the cable tension of cable-stayed bridges using the proposed method, the vibration method was applied to cable-stayed bridges in service to measure the tension.

• Journal of Venture Innovation
• /
• v.5 no.4
• /
• pp.23-39
• /
• 2022

This study was conducted to empirically analyze the factors influencing the intention to continue using live commerce, which was active as digital contacts become more prevailed due to the progress of the 4th industrial revolution and the COVID-19 pandemic. A research model was established by paying attention to the characteristics of influencers among various influencing factors. Influencer characteristics were subdivided into attractiveness, professionality, awareness, and entertainment. In addition, the dual mediating effect of interaction and trust was also tested between influencer's characteristics and the intention to continue using of live commerce. To this end, a survey was conducted targeting people who have experience using live commerce, and 300 valid samples were analyzed. The empirical analysis utilized SPSS 25.0 and Process Macro 4.0. As a result of the empirical analysis, it was found that attractiveness, professionality, awareness, and entertainment derived from the characteristics of influencers all had a significant positive (+) effect on the intention to continue using live commerce. The impact of the influence of variables that directly affect the intention to continue using was in the order of entertainment, awareness, professionality, and attractiveness. On the other hand, as a result of examining the dual mediating effect of interaction and trust, it was found that they all tested a mediating role between attractiveness, professionality, awareness, entertainment, and intention to continue using live commerce. Based on these research results, the academic and practical implications of this study were presented.

• Journal of Korean Society of Disaster and Security
• /
• v.16 no.2
• /
• pp.15-32
• /
• 2023

There are some difficulties such as safety problem and need of manpower in measuring discharge by submerging the instruments because of many floating debris and very fast flow in the river during the flood season. As an alternative, microwave water surface current meters have been increasingly used these days, which are easy to measure the discharge in the field without contacting the water surface directly. But it is also hard to apply the method in the sudden and rapidly changing field conditions. Therefore, the estimation of the discharge using the surface velocity in flood conditions requires a theoretical and economical approach. In this study, the measurements from microwave water surface current meter and rating curve were collected and then analyzed by the discharge estimation method using the surface velocity. Generally, the measured and converted discharge are analyzed to be similar in all methods at a hydraulic radius of 3 m or over or a mean velocity of 2 ㎧ or more. Besides, the study computed the discharge by the index velocity method and the velocity profile method with the maximum surface velocity in the section where the maximum velocity occurs at the high water level range of the rating curve among the target locations. As a result, the mean relative error with the converted discharge was within 10%. That is, in flood season, the discharge estimation method using one maximum surface velocity measurement, index velocity method, and velocity profile method can be applied to develop high-level extrapolation, therefore, it is judged that the reliability for the range of extrapolation estimation could be improved. Therefore, the discharge estimation method using the surface velocity is expected to become a fast and efficient discharge measurement method during the flood season.