• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.743-744
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• 2012

다기능성 복합센서의 모듈로 구성된 신호처리시스템에서 사용자 정보 및 상황을 실시간 인지하여 조명환경 및 생활환경을 분석할 수 있는 LED 디지털제어 융합기술이 주목을 받고 있다. LED 조명은 고효율, 장수명, 친환경적 장점과 나아가 LED 조명과 통신의 융합이 가능하며, 백열등 및 형광등을 대체할 차세대 일반조명으로 각광받고 있다. 제안된 시스템은 태양광을 이용한 지능형 LED 제어 시스템으로서, 사용자 예측 정보/상황 연계형 조명제어 기술 및 이에 따른 절감기술에 관한 연구이다. 또한 방전 전류의 10%를 주위의 환경에 따라서 보조 유색 LED를 적절히 점등함으로서 감성조명을 구현하고자 한다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제3권10호
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• pp.357-364
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• 2014

사물 인터넷 기반 초연결성 통신을 위한 일차적인 과제는 액서스 포인트, 기지국 등의 인프라를 거치지 않는 저전력, 손실 무선 네트워크 환경에서 사물 인터넷 기기들 간의 직접 통신 기법을 개발하는 것이다. 저전력 그리고 손실 네트워크 환경에서 사물 인터넷 디바이스들은 물론 라우터가 한정된 메모리를 사용하는 제한 조건을 가지고 있기 때문에 목적지 경로 정보를 지속적으로 유지할 수 없으며 다만 적은 수의 디폴트 라우터 정보만을 유지한다. IPv6주소를 그대로 활용하고 단순히 제어 메시지들의 양만 줄이는 데 초점을 둔 기존 경량화 라우팅 기법들과 달리 본 연구에서는 블룸필터 및 향상된 랭크개념을 활용하여 경량화 자동 주소 설정을 포함한 IPv6 이웃노드탐색 기법 및 경량화된 라우팅 프로토콜을 제안한다. 또한, 처음으로 사물 인터넷 기반 기기 간 손실 있는 무선 환경을 다양한 확률분포함수를 따르면서 에러가 발생하도록 모델링하여 성능평가를 수행했다. 특히, 제안하는 기법은 동적으로 무선 링크가 변하여 데이터 손실이 발생해도 향상된 랭크 정보를 바탕으로 다중 경로 정보를 지역적으로 활용하여 견고성을 높였다. 성능평가 결과 제안하는 기법은 RPL 기반 라우팅 프로토콜에 비해서 최대 40%까지 성능향상을 보일 수 있었다.

• 한국HCI학회논문지
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• 제2권1호
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• pp.57-63
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• 2007

본 연구는 Tiled Display 기반의 협업 환경에서 인터랙션을 위한 적외선 포인터를 구현하는 목적으로 진행되었다. 적외선 발광 다이오드에서 나오는 빛을 인지하여 포인터의 궤적을 인식하는 기술과 이를 응용하여 여러 분야에 접목시키는 것에 주안점을 두었다. 기본적인 마우스 클릭 기능과 단순 포인팅 기능을 제공하는 기존의 포인터와는 달리 적외선 발광 다이오드가 탑재된 포인터를 조립, 이용하여 기존의 기능뿐만 아니라 컴퓨터와 사용자 간의 새로운 커뮤니케이션 수단을 제공하고 있다. 장점으로는 책상, 테이블과 같은 제한된 공간을 벗어나서 적외선 투과 필터가 장착된 카메라 하나만 설치할 수 있는 곳이면 구현이 가능하며 적외선을 이용하므로 가시광선의 영향을 적게 받아 효율적으로 영상 처리를 할 수 있다는 데에 있다. 그리고 적외선을 이용한 사용자의 모션을 추적, 인식하여 복합적이 여러 가지 기능을 실행할 수 있으며, 보다 더 사용자와 인터랙티브한 작업이 가능하다. 구현된 하드웨어와 소프트웨어 시스템은 프레젠테이션 및 게임 컨트롤 등에 사용되었다.

• Journal of Biosystems Engineering
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• 제38권4호
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• pp.270-278
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• 2013

Purpose: Using agricultural machinery was not easy in the conventional shading structure, specified as a standard facility by standard cultivation methods for ginseng. Thus, this study designed the new types of facility allowing machine access by modifying the conventional type. Methods: Two types of facility (i.e. wide roof type and long & short roof type) were designed and installed in an experimental site to evaluate its growing environments and applicability of riding-type cultivator. Results: From the results of incoming light measurement, all three types (i.e. two new types and a conventional type) of shading structures blocked the incoming light after 9:00 am. The temperature distribution inside the new types was similar with the one in the conventional type, so the growth of ginseng was in good condition in all three types of facility. The riding-type cultivator was operated well with the low speed first gear of 0.13 m/s in the new types. However, a long & short typed roof needs to be raised 18 cm height in order to use the cultivator. Conclusions: With the results of this study, the new types of roof can be used in the ginseng farm in that they satisfied the growing environments for ginseng and the needs for agricultural mechanization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권8호
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• pp.2930-2947
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• 2014

With the rapid growth of the communication technology, intelligent terminals (i.e. PDAs and smartphones) are widely used in many mobile applications. To provide secure communication in mobile environment, in recent years, many user authentication schemes have been proposed. However, most of these authentication schemes suffer from various attacks and cannot provide provable security. In this paper, we propose a novel remote user mutual authentication scheme for multi-server environments using elliptic curve cryptography (ECC). Unlike other ECC-based schemes, the proposed scheme uses ECC in combination with a secure hash function to protect the secure communication among the users, the servers and the registration center (RC). Through this method, the proposed scheme requires less ECC-based operations than the related schemes, and makes it possible to significantly reduce the computational cost. Security and performance analyses demonstrate that the proposed scheme can solve various types of security problems and can meet the requirements of computational complexity for low-power mobile devices.

• 로봇학회논문지
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• 제18권4호
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• pp.487-495
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• 2023

This paper presents a method for autonomous exploration of indoor environments using a 2-dimensional Light Detection And Ranging (LiDAR) scanner. The proposed frontier-based exploration method considers navigability from the current robot position to extracted frontier targets. An approach to constructing the point cloud grid map that accurately reflects the occupancy probability of glass obstacles is proposed, enabling identification of safe frontier grids on the safety grid map calculated from the point cloud grid map. Navigability, indicating whether the robot can successfully navigate to each frontier target, is calculated by applying the skeletonization-informed rapidly exploring random tree algorithm to the safety grid map. While conventional exploration approaches have focused on frontier detection and target position/direction decision, the proposed method discusses a safe navigation approach for the overall exploration process until the completion of mapping. Real-world experiments have been conducted to verify that the proposed method leads the robot to avoid glass obstacles and safely navigate the entire environment, constructing the point cloud map and calculating the navigability with low computing time deviation.

• 반도체디스플레이기술학회지
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• 제23권1호
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• pp.71-78
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• 2024

In indoor environments, since global positioning system (GPS) signals can be blocked by obstacles, such as building structure. the performance of GPS-based positioning methods can be degraded because of the loss of GPS signals. To solve this problem, various localization schemes using inertial measurement unit (IMU) sensors, such as gyroscope, accelerometer, and magnetometer, have been proposed to enhance the positioning accuracy in indoor environments. IMU-based positioning methods can estimate the location of the user by calculating the velocity and heading angle of the user without the help of GPS. However, low-cost MEMS IMUs may lead to drift error and large bias. In addition, positioning errors in IMU-based positioning approaches can be caused by the irrelevant motion of the pedestrian. In this study, we propose an enhanced indoor positioning method that provides more reliable localization results by using the camera, light detection and right (LiDAR), and ARKit framework on the iPhone. Through reliable positioning results and augmented reality (AR) experiences, our indoor positioning system can provide indoor space guidance services.

• 대한가정학회지
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• 제46권1호
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• pp.117-129
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• 2008

In present study, using 1572 low-income families and 266 Head Start teachers from Family and Child Experiences Survey (FACES) in the U.S., we examined the effects of mothers' reading and the characteristics of interaction between teacher-child interaction on 4-and 5-year-olds' cognitive development represented by their verbal and numerical abilities. Frequencies of mothers' reading at home consistently predicted higher scores of children's Peabody Picture Vocabulary Test and Woodcock Johnson Applied Problems. Teachers' sensitivity and permissiveness in their interactions with children in classroom were positively related to children's verbal abilities and teachers' sensitivity predicted better numerical abilities of children after controlling for mothers' reading and the characteristics of family and teacher. The findings shed light on the contributions of teacher behaviors and familial factors to children's cognitive development calling for attention to the need for parent education on cognitively stimulating family environments and continuing education for early childhood teachers focusing on quality interactions with young children.

• 설비공학논문집
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• 제28권9호
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• pp.343-349
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• 2016

Due to the recent increase in lighting energy consumption in buildings, there are a growing number of studies seeking solutions this problem. The effectiveness of light-shelves as natural lighting systems to solve this problem has been recognized, and various studies regarding such systems are being carried out currently. However, the lighting efficiency of light-shelves decreases if illumination intensity is low-such as at night time, and it also obstructs the views of building occupants. Therefore, the purpose of this study is to examine a movable drawer type light-shelf which allows for the width of the reflector to be adjusted and verify its performance through a simulated test-bed. The following conclusions were reached. 1) The purpose of this study is to solve the problem previously associated with the light-shelf system- of obstructed views-by responding to external environments and minimizing the width of the light-shelf at night time when the efficiency of the light-shelf declines. 2) The proper variables of the movable drawer type light-shelf which enables the width adjustment of the reflector were ascertained in this study according to four solar terms : a width of 0.6 m at an angle of $20^{\circ}$, a width of 0.4m with an angle of $20^{\circ}$, and a width of 0.1 m with an angle of $20^{\circ}$ were determined for the summer solstice, fall/spring equinoxes, and winter solstice respectively; revealing that width adjustment of the light-shelf is a significant factor. 3) The movable drawer type light-shelf which enables${\backslash}$width adjustment of the reflector suggested in this study can reduce the lighting energy consumption by 18.7% and 14.3% in comparison to previous light-shelves with a fixed width of 0.3 m and 0.6m, indicating that it is effective for saving energy.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 추계학술대회 논문집
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• pp.89-92
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• 2008

강의실은 학생들이 학습을 하는 공간으로 정확한 정보취득과 시작업을 요한다. 강의실의 조명환경에 대한 문제점은 학습효과의 저하뿐만 아니라 학생들의 시력에도 악영향을 미치게 된다. 따라서 학생들이 대부분의 시간을 보내는 강의실의 알맞은 조명을 얻기 위한 연구가 필요하다. 현재의 대학 강의실의 일반조명시스템과 다운라이트를 적용한 조명시스템을 컴퓨터 시뮬레이션을 통하여 비교, 검토해보면 다운라이트를 적용한 조명 시스템은 강의실의 조도를 개선하며, 등기구 초기 투자비용의 절감으로 경제성을 향상시키고 에너지 절약을 가져올 수 있다.