• Journal of Multimedia Information System
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• 제1권2호
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• pp.101-110
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• 2014

The purpose of this research is to extend Ad-hoc network system lifetime with the proposed routing protocol which has considered hop lifetimes of the nodes while guaranteeing QoS in the establishment process of Ad-hoc network communication paths. Based on another power aware routing system that proposed in the advanced research [1], we are proposing an alternative power aware routing system in which nodes' hop lifetimes are compared in order to extend the lifetime of an Ad-hoc network system and delay factors have been considered for the assurance of QoS. The research of the routing protocol in this paper, which aims to maximize the system survival time considering power consumption status during the path searching in MANET and pursues the mechanism that controls hop delays for the same reason, can be applied to the study of WSN. The study concerning such phenomena is essential so that the proposed protocol has been simulated and verified with NS-2 in Linux system focusing on the lifetimes of the hops of the nodes. Commercialization of smart devices and arrival of the ubiquitous age has brought about the world where all the people and things are connected with networks. Since the proposed power aware method and the hop delay control mechanism used to find the adequate communication paths in MANET which mainly uses batteries or in WSN, they can largely contribute to the lifetime extension of the network system by reducing power consumptions when utilized for the communications attempts among soldiers during military operation, disaster areas, temporary events or exhibitions, mobile phone shadow areas, home networks, in-between vehicle communications and sense networks, etc. This paper presents the definitions and some advantages regarding the proposed outing protocol that sustain and extend the lifetime of the networks.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제15권4호
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• pp.3-11
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• 2009

As de-schooling students (students who leave schools) have been produced and increased in middle and high schools every year since 1990s, urban alternative schools have founded with Seoul as the center. The objects of such urban alternative schools are de-schooling teenagers, and their educational goal is to make the students to discover their own values and grow as members of the community by accomplishing their healing and growth. Most of students in alternative schools have excessive self-centered feeling than ordinary people, and since they don't have exchanges with others, they have to receive holistic healing along with education. Here, 'healing' is a method of approaching to health through environmental, psychological, social and cultural supports unlike 'treatment' used for medical means. Therefore, holistic healing for alternative schools' students has to accomplish self-knowledge, self-control, and self-healing without repulsion through spaces of healing environments instead of heavy-handed exchanges. This study has integrated a theory of Max $L{\ddot{u}}scher$ who suggested a psychological healing theory in terms of internal character and a theory of Rudolf Steiner who suggested it in terms of practical and holistic sense and analyzed Sungmisan School, one of urban alternative schools in Seoul through the integrated theory. The analysis of the integrated theory are intended to emphasize the importance of healing environments and suggest methods in creating healing environments for urban alternative schools in the future.

• 한국전자파학회논문지
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• 제30권2호
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• pp.152-159
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• 2019

도플러 레이다는 단일 주파수의 정현파를 이용하므로 움직이는 이동체의 속도만을 측정할 수 있다고 알려져 있다. 일반적으로 이동체의 거리를 측정하기 위해서는 FMCW 레이다나 펄스 레이다를 이용하여야 하는데, 이 경우 하드웨어 구성 및 신호처리가 복잡할 뿐만 아니라, 주파수 대역폭을 넓게 사용하기 때문에 24 GHz나 77 GHz 대역의 밀리미터파를 사용할 수밖에 없어 가격이 비싸다. 따라서 가격이 저렴한 도플러 레이다에서 다중 톤 주파수를 이용하여 이동체의 속도 외에 거리까지 센싱하는 연구가 시작되고 있다. 이에 본 연구에서는 2.4 GHz 도플러 레이다에 내장된 PLL만을 이용한 주파수 조정만으로도 이동체의 거리 센싱이 가능함을 보인다. 특히, 기존에 제안된 DC 기반의 거리 계산에서 필요한 DC 정보를 제거하고, 교류결합된 AC 정보만을 이용하여 거리를 센싱할 수 있음을 보인다. 제안된 기술은 2.4 GHz 대역의 이동체 식별용 특정소출력 무선기기 기술기준을 만족하므로 45 dBm EIRP 출력을 이용하여 이동체 거리 센싱이 필요한 다양한 응용이 가능하다.

• 한국학교보건학회지
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• 제34권1호
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• pp.76-86
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• 2021

Purpose: This study was conducted to describe the experience of school health teachers in regard to the COVID-19 pandemic in South Korea. Methods: We conducted a qualitative study using content analysis. Ten school health teachers were recruited from 6 elementary schools, 2 middle schools and 2 high schools in Seoul, using purposive sampling. They participated in semi-structured in-depth interviews in person or using an online communication system from January to February, 2021. Interviews were transcribed verbatim and analysed using qualitative content analysis. Results: Three main categories and nine generic categories emerged from the analysis. Firstly, it was discovered that school health teachers had psychological and physical stress to cope with COVID-19 due to the 1) fear of the unexpected infectious disease, 2) burden of having to deal with it alone, 3) breakdown of personal life and physical exhaustion and 4) heavy duty as a health teacher caused by the lack of an organic cooperation system with institutions related to school infectious diseases. Secondly, school health teachers had an increased sense of empowerment in regard to infectious disease management as a result of 1) feeling rewarded and appreciated and 2) gaining confidence and trust in infectious disease management. Finally, school health teachers experienced the urgent need for an effective response strategy for infection control because of the 1) confusion over infectious disease response due to lack of practical manuals applicable to the field as well as training, 2) disappointing response system without an expert response team dedicated to managing infectious diseases in schools, and 3) growing awareness of the need for change. Conclusion: It is expected that school health teachers' experience of COVID-19 will be used as important data for building effective and advanced school infectious disease response systems.

• 공학교육연구
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• 제24권1호
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• pp.24-33
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• 2021

As online learning continues to be extended, many engineering colleges are engaged in online learning activities. One of the core competencies required of engineering students in a knowledge-convergence society is communication skills. Online discussion activities are frequently used in educational field to improve communication skills. Efforts are being made to provide visual dashboards in online discussion activity systems to more effectively support online discussion activities. However there is less qualitative studies on students' experience in discussion activities. The purpose of this study is to explore the experience of engineering students participating in discussion activities using online discussion systems and visual dashboards. We interviewed 15 students who participated in online discussion activities to achieve their research objectives about their experience in utilizing the online discussion system, their perception of visual dashboards, and their experience in discussion activities. As a result of the study, students' perception of the use of the online discussion activity system, the visual dashboard, and the perception of a sense of social presence were understood. To be more effective in providing tool support, such as discussion activity systems and visual dashboards in online discussion activities, instructors need to understand the nature of learners' online discussion activities.

• 한국전자통신학회논문지
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• 제12권1호
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• pp.53-60
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• 2017

현재 대부분의 초음파를 이용한 거리 측정 기술은 송신부로부터 수신기까지 초음파가 진행하는 시간 즉, TOF(: Time of Flight)를 측정하여 그 동안 음파가 진행한 거리를 산출하는 방법을 활용한다. 이 경우 거리 측정 정확도를 높이기 위해서는 정확한 TOF의 측정이 필요하다. 본 논문은 정확한 TOF를 산출하기 위해 초음파 송수신기의 수학적 모델을 이용하여 수신된 파형의 수학적 모델을 얻어내고 이를 바탕으로 TOF를 산출하는 방식을 제안한다. 이 방식은 트리거링 후부터 수신된 파형를 이미 얻어진 수학적 모델과 최소자승법을 이용하여 비교하여 초음파 신호가 수신기에 도달한 시점을 역으로 추정하는 방식이다. 제안된 방법을 사용할 경우 트리거링 시점의 변동에 의한 영향을 줄일 수 있음을 실험을 통하여 확인하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2010년도 춘계학술발표대회 초록집
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• pp.22-22
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• 2010

주물과 용접에서 응고 과정에서 수지상간 또는 세포상간 영역에서 최종적으로 응고하는 저융점 공정 조성의 상이 응고균열의 발생에 직접적으로 영향을 미친다. 작은 량의 공정조성의 액상 필름이 응고된 고상과 고상 사이에 존재하게 되면 이 영역에서 생성되는 불연속부는 응고균열로 남게 된다. 이러한 공정조성 액상의 유동성이 좋고 충분한 부피로 존재한다면 응력과 부피수축등으로 생성된 수지상간, 또는 세포상강 영역에서 생성된 불연속부로 용이하게 유동하여 불연속부를 충진하게 된다. 따라서 발생한 응고균열이 치유되는 효과를 얻을 수 있다. 반면에 공정조상의 상이 전혀 존재하지 않는 순금속 응고의 경우에는 최종 응고 단계에 액상 필름이 존재하지 않게 되어 고상과 고상의 인터로킹이 가능하게 되어 균열 발생 가능성이 희박하다. 따라서 응고균열 발생을 제어할 수 있는 효과적인 방법은 용탕이나 용접금속의 조성을 공정 조성에 가깝게 제어하는 것이다.

• Macromolecular Research
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• 제17권7호
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• pp.528-532
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• 2009

The size and shape of free volume (FV) holes available in membrane materials control the rate of gas diffusion and its permeability. Based on this principle, a segmented, thermo-sensitive polyurethane (TSPU) membrane with functional gate, i.e., the ability to sense and respond to external thermo-stimuli, was synthesized. This smart membrane exhibited close-open characteristics to the size of the FV hole and water vapor permeation and thus can be used as smart food packaging materials. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), positron annihilation lifetimes (PAL) and water vapor permeability (WVP) were used to evaluate how the morphological structure of TSPU and the temperature influence the FV holes size. In DSC and DMA studies, TSPU with a crystalline transition reversible phase showed an obvious phase-separated structure and a phase transition temperature at $53^{\circ}C$ (defined as the switch temperature and used as a functional gate). Moreover, the switch temperature ($T_s$) and the thermal-sensitivity of TSPU remained available after two or three thermal cyclic processes. The PAL study indicated that the FV hole size of TSPU is closely related to the $T_s$. When the temperature varied cyclically from $T_s-10{\circ}C$ to $T_s+10^{\circ}C$, the average radius (R) of the FV holes of the TSPU membrane also shifted cyclically from 0.23 to 0.467 nm, exhibiting an "open-close" feature. As a result, the WVP of the TSPU membrane also shifted cyclically from 4.30 to $8.58\;kg/m^2{\cdot}d$, which produced an "increase-decrease" response to the thermo-stimuli. This phase transition accompanying significant changes in the FV hole size and WVP can be used to develop "smart materials" with functional gates and controllable water vapor permeation, which support the possible applications of TSPU for food packaging.

• 한국정보통신학회논문지
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• 제11권6호
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• pp.1228-1234
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• 2007

이 논문에서는 정보영재 교육 중에서 프로그래밍을 위한 사고력 신장에 적합한 교육 프로그램 모형을 개발하고, Tic-tac-toe 문제를 실제적인 예로 보여 제안된 교육 프로그램의 타당성과 유효성을 검증하였다. 이 논문에서 제안된 모델에서는 자료구조로는 게임 트리를 사용하며 제어구조로는 게임 트리의 탐색에 기반한 사고력 신장 교육 프로그램으로 4단계로 구성되는 모형으로 구성된다. 이 모델을 통하여 학생들은 문제를 게임 트리로 표현하는 방법을 학습하게 되며, 게임 트리의 탐색 방법을 통하여 트리로 구성된 문제를 해결하는 방법을 배우게 된다. 이 교육 프로그램에서 목표로 하는 사고력 신장을 위한 정보영재의 내적 능력에는 유창성, 직관력, 독창성, 집중력, 상상력, 분석력, 도형력, 공간력, 종합력, 문제해결력 등이 포함된다.

• The Plant Pathology Journal
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• 제38권6호
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• pp.646-655
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• 2022

Pepper mild mottle virus (PMMoV), one of the most prevalent viruses in chili pepper (Capsicum annuum L.) is a non-enveloped, rod-shaped, single-stranded positive-sense RNA virus classified in the genus Tobamovirus. The supernatants of five bacterial cultures (Pseudomonas putida [PP], Bacillus licheniformis [BLI], P. fluorescens [PF], Serratia marcescens [SER], and B. amyloliquifaciens [BA]) were analyzed to find novel antiviral agents to PMMoV in chili pepper. Foliar spraying with supernatants (1:1, v/v) obtained from Luria-Bertani broth cultures of PP, BLI, PF, SER, and BA inhibited PMMoV infection of chili pepper if applied before the PMMoV inoculation. Double-antibody sandwich enzyme-linked immunosorbent assay showed that treatments of five supernatants resulted in 51-66% reductions in PMMoV accumulation in the treated chili pepper. To identify key compounds in supernatants of PP, BLI, PF, SER, and BA, the supernatants were subjected to gas chromatography-mass spectrometry. The 24 different types of compounds were identified from the supernatants of PP, BLI, PF, SER, and BA. The compounds vary from supernatants of one bacterial culture to another which includes simple compounds-alkanes, ketones, alcohols, and an aromatic ring containing compounds. The compounds triggered the inhibitory effect on PMMoV propagation in chili pepper plants. In conclusion, the cultures could be used to further conduct tissue culture and field trial experiments as potential bio-control agents.