• 정보교육학회논문지
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• 제23권5호
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• pp.461-467
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• 2019

융복합 응용의 일반화로 라즈베리파이나 아두이노 임베디드형 제어 보드의 활용이 늘고 있다. 이러한 제어장치 설치는 상시 전력이 부재한 상황에서도 운영되어야 하는 경우가 많다. 이러한 경우에 흔히 태양광을 이용하기 때문에 충분한 전력 확보가 쉽지 않다. 본 논문에서는 이러한 저전력 환경 하에서도 작동할 수 있는 효과적인 제어 체계를 제안하고자 한다. 본 논문에서 구성한 실험 기기는 일정한 주기별로 DSLR 카메라 촬영하는 장치이다. 장치의 제어 모듈은 라즈베리파이와 아두이노 보드를 결합한 복합물이며, 아두이노 보드가 정해진 주기별로 라즈베리파이 보드를 동작시키도록 구성하였다. 본 논문에서는 이러한 전력 제어를 위한 프로그램을 개발하였고 이 펌웨어에 의하여 라즈베리파이의 전력 소모를 일자별, 시간별로 측정하여 전체 시스템의 효율성을 검증하였다. 아두이노 보드는 정한 간격마다 라즈베리파이에 전력을 공급하여 카메라에 슈팅 신호를 전송하도록 하였다. 실험결과, 10일간의 실험 기간 동안 일정하고 안정적인 전력 소모가 측정되었다. 결국 아두이노를 결합하여 절전하는 경우 라즈베리의 소비전력량을 약 81% 절감한 것으로 조사되었다.

• Journal of Ship and Ocean Technology
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• 제10권4호
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• pp.12-23
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• 2006

In this paper, a numerical study is carried out to investigate the turbulent flow around a twin-skeg container ship model with rudders including propeller effects. A commercial CFD code, FLUENT is used with body forces distributed on the propeller disk to simulate the ship stem and wake flows with the propeller in operation. A multi-block, matching, structured grid system has been generated for the container ship hull with twin-skegs in consideration of rudders and body-force propeller disks. The RANS equations for incompressible fluid flows are solved numerically by using a finite volume method. For the turbulence closure, a Reynolds stress model is used in conjunction with a wall function. Computations are carried out for the bare hull as well as the hull with appendages of a twin-skeg container ship model. For the bare hull, the computational results are compared with experimental data and show generally a good agreement. For the hull with appendages, the changes of the stem flow by the rudders and the propellers have been analyzed based on the computed result since there is no experimental data available for comparison. It is found the flow incoming to the rudders has an angle of attack due to the influence of the skegs and thereby the hull surface pressure and the limiting streamlines are changed slightly by the rudders. The axial velocity of the propeller disk is found to be accelerated overall by about 35% due to the propeller operation with the rudders. The area and the magnitude of low pressure on the hull surface enlarge with the flow acceleration caused by the propeller. The propellers are found to have an effect on up to the position where the skeg begins. The propeller slipstream is disturbed strongly by the rudders and the flow is accelerated further and the transverse velocity vectors are weakened due to the flow rectifying effect of the rudder.

• 한국전자통신학회논문지
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• 제16권2호
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• pp.379-384
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• 2021

사람들이 인공 지능 분야를 계속 연구하고 제안 한다. 그 때문에 상대적으로 성숙한 인공지능 기술이 일상생활에 더 많이 활용된다. 평소 어디서나 볼 수 있는 생활용품들이 지능화되기 시작하고 있다. 그러나 미러는 생활용품에서 가장 많이 쓰이는 용품 이다. 그 인공 지능 기술을 미러에 적용하는 데 가장 적합 하다. 이 논문의 연구 결과는 라즈베리 pi를 기반으로 설계된 스마트 미러가 날씨, 온도, 인사를 표시하고, 인간-미러 상호작용 기능을 가지고 있다. 본 논문 연구방법은 라즈베리 pi 3B +를 핵심 컨트롤러로 사용하고 Google 어시스턴트를 지능형 제어로 사용한다. 라즈베리 pi의 자체 WiFi를 통해 네트워크에 연결하면 미러가 자동으로 시간, 날씨 및 뉴스 정보 기능을 표시하고 업데이트 할 수 있다. 키워드를 사용하여 Google 어시스턴트를 깨운 다음 미러를 제어하여 음악을 재생하고 시간을 상기시키는 등의 작업을 할 수 있다. 스마트 미러 음성 상호 작용의 기능을 실현한다. 또한 이 연구에 사용 된 하드웨어는 모두 모듈식 어셈블리이고, 나중에 사용자가 직접 조립하는 것이 편리 하며. 저렴한 가격으로 시장 진흥에 적합하다.

• 한국추진공학회지
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• 제25권5호
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• pp.36-52
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• 2021

뉴 스페이스 시대를 맞아 군집 초소형 위성의 활용이 전 세계적으로 증가함에 따라, 위성의 정밀제어를 위한 추력기가 필수적으로 요구되고 있다. 전계방출 전기추진(Field Emission Electric Propulsion, FEEP) 추력기는 추진제로 액체 금속을 사용하는데, 강한 전기장에 의해 이온화된 액체금속을 가속시키는 방식의 추력기이다. FEEP 추력기는 1 µN급에서 1 mN급까지의 추력 범위와 10,000 s 수준에 이르는 큰 비추력을 가지며, 구조가 단순하고 소형화가 가능하여 초소형 위성의 다양한 자세 및 궤도 제어 임무에 적합하다. 본 논문에서는 FEEP 추력기의 개요를 소개하고, 연구개발 현황에 대해서 살펴보고자 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권4호
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• pp.1224-1248
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• 2022

In various sensor network applications, such as climate observation organizations, sensor nodes need to collect information from time to time and pass it on to the recipient of information through multiple bounces. According to field tests, this information corresponds to most of the energy use of the sensor hub. Decreasing the measurement of information transmission in sensor networks becomes an important issue.Compression sensing (CS) can reduce the amount of information delivered to the network and reduce traffic load. However, the total number of classification of information delivered using pure CS is still enormous. The hybrid technique for utilizing CS was proposed to diminish the quantity of transmissions in sensor networks.Further the energy productivity is a test task for the sensor nodes. However, in previous studies, a clustering approach using hybrid CS for a sensor network and an explanatory model was used to investigate the relationship between beam size and number of transmissions of hybrid CS technology. It uses efficient data integration techniques for large networks, but leads to clone attacks or attacks. Here, a new algorithm called SBEA (Snowball Endurance Algorithm) was proposed and tested with a bow. Thus, you can extend the battery life of your WSN by running effective copy detection. Often, multiple nodes, called observers, are selected to verify the reliability of the nodes within the network. Personal data from the source centre (e.g. personality and geographical data) is provided to the observer at the optional witness stage. The trust and reputation system is used to find the reliability of data aggregation across the cluster head and cluster nodes. It is also possible to obtain a mechanism to perform sleep and standby procedures to improve the life of the sensor node. The sniffers have been implemented to monitor the energy of the sensor nodes periodically in the sink. The proposed algorithm SBEA (Snowball Endurance Algorithm) is a combination of ERCD protocol and a combined mobility and routing algorithm that can identify the cluster head and adjacent cluster head nodes.This algorithm is used to yield the network life time and the performance of the sensor nodes can be increased.

• Wind and Structures
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• 제35권3호
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• pp.177-191
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• 2022

Trains emerging on a streamlined bridge-girder may have salient interference effects on the aerodynamic properties of the bridge. The present paper aims at investigating these interferences by wind tunnel measurements, covering surface pressure distributions, near wake profiles, and flow visualizations. Experimental results show that the above interferences can be categorized into two primary effects, i.e., an additional angle of attack (AoA) and an enhancement in flow separation. The additional AoA effect is demonstrated by the upward-moved stagnation point of the oncoming flow, the up-shifted global symmetrical axis of flow around the bridge-girder, and the clockwise-deflected orientation of flow approaching the bridge-girder. Due to this additional AoA effect, the two critical AoAs, where flow around the bridge-girder transits from trailing-edge vortex shedding (TEVS) to impinging leading-edge vortices (ILEV) and from ILEV to leading-edge vortex shedding (LEVS) of the bridge-girder are increased by 4° with respect to the same bridge-girder without trains. On the other hand, the underlying flow physics of the enhancement in flow separation is the large-scale vortices shedding from trains instead of TEVS, ILEV, and LEVS governed the upper half bridge-girder without trains in different ranges of AoA. Because of this enhancement, the mean lift and moment force coefficients, all the three fluctuating force coefficients (drag, lift, and moment), and the aerodynamic span-wise correlation of the bridge-girder are more significant than those without trains.

• 한국인터넷방송통신학회논문지
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• 제22권1호
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• pp.59-63
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• 2022

근래에 와서 유틸리티들을 무선으로 원격제어 하는 스마트 팩토리 무선 이동 통신 기술에 대한 연구가 활발히 진행되고 있다. Wi-SUN(Wireless Smart Utility Network) 얼라이언스에서는 EEE802.15.4g/e에 기반한 새로운 무선통신 표준화 규격으로 스마트팩토리와 같은 플랫폼 구축에 적합한 Wi-SUN 프로토콜 구조를 제시하였다. IEEE802.15.4e의 CSL(Coordinated Sampled Listening) 모드 MAC(Media Access Control)의 전력소모 측면의 성능을 분석하고 효율적 운용을 위한 고려 사항을 살펴본다. CSL-MAC은 비동기 방식으로 수신단에서 전력소모를 획기적으로 줄일 수는 있지만 송신단에서는 과도한 웨이크업시퀀스로 전력소모가 발생하는 단점을 가지는 것을 알 수 있었다.

• 한국콘텐츠학회논문지
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• 제22권5호
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• pp.553-564
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• 2022

이 연구의 목적은 <삼시세끼> 어촌편 1이 재현한 가족을 살펴보는 것으로, 이야기 전개구성과 등장인물의 관계 특성을 서사분석을 활용해 분석하였다. <삼시세끼>는 '기상-자유시간-아침-점심-저녁-휴식-취침'의 비교적 단순한 전개구성을 보였다. 각 등장인물에게는 주된 공간과 역할을 배치함으로써 '차줌마', '바깥양반', '호주니'의 캐릭터를 완성해갔다. 출연진이 모두 남성임에도 이들에게는 아내/주부/엄마, 남편/가장/아빠, 아들의 가족지위가 부여되었고, 매우 고정된 감정과 획일적 행동의 가족실천이 탄탄한 관계구조 속에서 반복되었다. 동시에 유자녀 가족, 양부모 가족, 이성애가족, 핵가족이라는 전형적 근대가족, 정상가족, 표준가족을 연출하였다. 즉 <삼시세끼>는 스위트 홈의 표상을 적극 차용해 정상가족 이데올로기를 강화시켰다.

• 자동차안전학회지
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• 제15권2호
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• pp.35-41
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• 2023

On December 19, 2015, as Article 29-3 (Installation of Accident Recording Devices and Provision of Information) of Motor Vehicle Management Act came into force, In Korea, the EDR (Event Data Recorder) reports are often used for the analysis of various traffic accident cases such as multiple collisions, traffic insurance crimes, and sudden unintended acceleration (SUA), and the others. So many investigators have analyzed the driver's behavior and vehicle situation by comparing the time zero in the EDR report to the actual crash time in dash-cam (or CCTV). Time zero (T0) is defined as the reference time for the record interval or time interval when recording an accident in Article 56-2, Enforcement rule of Performance and Standard for Automobile and Automotive parts. Also in the EDR report, time zero (T0) is defined as whichever of the following occurs first; 1. "wake-up" by an air-bag control system, 2. Continuously running algorithms (by monitoring of longitudinal or lateral delta-V), 3. Deployment of a non-reversible deployment restraint. We have already proposed the "Flowchart & Checklist" to adopt the EDR report for traffic accident investigation and the necessity of specialized institutions or courses to systematically educate or analyze the EDR data. Therefore, in this paper, we report to traffic accident investigators notable points and analysis methods based on some real-world traffic accidents that can be misjudged in specifying time zero (T0).

• 한국학교보건학회지
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• 제36권3호
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• pp.113-125
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• 2023

Purpose: The purpose of this study is to develop a model for predicting mental health risk among adolescents based on health behavior information by employing a hybrid machine learning method. Methods: The study analyzed data of 51,850 domestic middle and high school students from 2022 Youth Health Behavior Survey conducted by the Korea Disease Control and Prevention Agency. Firstly, mental health risk levels (stress perception, suicidal thoughts, suicide attempts, suicide plans, experiences of sadness and despair, loneliness, and generalized anxiety disorder) were classified using the k-mean unsupervised learning technique. Secondly, demographic factors (family economic status, gender, age), academic performance, physical health (body mass index, moderate-intensity exercise, subjective health perception, oral health perception), daily life habits (sleep time, wake-up time, smartphone use time, difficulty recovering from fatigue), eating habits (consumption of high-caffeine drinks, sweet drinks, late-night snacks), violence victimization, and deviance (drinking, smoking experience) data were input to develop a random forest model predicting mental health risk, using logistic and XGBoosting. The model and its prediction performance were compared. Results: First, the subjects were classified into two mental health groups using k-mean unsupervised learning, with the high mental health risk group constituting 26.45% of the total sample (13,712 adolescents). This mental health risk group included most of the adolescents who had made suicide plans (95.1%) or attempted suicide (96.7%). Second, the predictive performance of the random forest model for classifying mental health risk groups significantly outperformed that of the reference model (AUC=.94). Predictors of high importance were 'difficulty recovering from daytime fatigue' and 'subjective health perception'. Conclusion: Based on an understanding of adolescent health behavior information, it is possible to predict the mental health risk levels of adolescents and make interventions in advance.