• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.463-468
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• 2007

The abnormal sound of generator frame is analyzed by a acceleration signal. The spike-like time signal is major characteristics of impacting force. The distributional map of vibration level is one of visualization method. With map, noise source was easily detected. After de_assembly of generator, loose part of internal component is the source of impact force by mechanical movement of stator inherently. In contact condition of part with clearance, the level of impact signal is different at each revolution and impact signal did not happens periodically.

• 한국시스템다이내믹스연구
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• 제10권1호
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• pp.33-60
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• 2009

This study explores the limitation in making a causal model through an existing case and proposes an alternative plan to improve a theoretical system of causation modeling. To make a dynamic and actual model, several principles are needed such as reality based analysis of system structures and dynamics, consistent expression of causations, conversion of numerical formulas to causal relations, classification and arrangement of variables by size of concept, etc. However, it is hard to find cases to apply these considerations from existing models in System Dynamics. Therefore, this study verifies errors of derived models from literatures and proposes principles and guides that should be considered to make a sound dynamic model on a causal map. It contributes to making an opportunity for exciting public opinion to improve theory about causal maps, yet it has limitation that the study does not advance forward to the experimental step. For future study, it plans to make up by classifying and leveling causal variables, developing a dynamic BSC model.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2021년도 하계학술대회
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• pp.283-285
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• 2021

본 논문에서는 수중에서 선박 하부에 붙은 오손생물(fouling organism)을 탐지하고 격자지도(grid map)로 나타내는 시스템을 제안한다. 제안하는 시스템은 소나(sound navigation and ranging: SONAR) 센서와 오손생물사이의 시간 데이터를 수집한 후, 라즈베리 파이 4(raspberry pi 4)에서 수집된 데이터를 이용해 격자지도에 맵핑(mapping)함으로써, 선저하부의 상태를 파악하는데 도움을 줄 수 있다. 본 논문에서는 제안된 지도 시스템을 이용하여 선박 하부에 붙은 오손생물의 분포를 확인할 수 있다.

• 한국소음진동공학회논문집
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• 제20권5호
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• pp.502-509
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• 2010

A test facility which can simultaneously measure turbocharger operating condition variables and vibro-acoustic emission in the situations that are quite similar to real internal combustion engine operating conditions has been introduced. Using this facility, a new method sweeping from full open throttle to deep surge region along constant speed curves can be utilized instead of the stationary method that has been traditionally used to obtain turbocharger compressor maps. Data covering an extensive range of the compressor performance map have been collected and analyzed. An experimental study is performed to define a noise diagram that correlates vibro-acoustic measurements to aerothermodynamic operating conditions. An instrumentation set in the facility allows the automatic definition of the operating point on the turbine and compressor map of the turbocharger. Also, radiated sound pressure and casing vibration data corresponding to the point are obtained by a microphone in the vicinity of the compressor casing and an accelerometer on the casing. The major source(s) of noise at specific operating point on the map can be easily identified with these maps. Also, acoustic characteristics of a given turbocharger at the vicinity of the surge as well as in the surge are also defined. Finally, the possibility to define mild surge region of a turbocharger using vibro-acoustic measurements is studied.

• 제어로봇시스템학회논문지
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• 제13권3호
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• pp.249-255
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• 2007

Under the situation of a fire, it is difficult for a rescue robot to use sensors such as vision sensor, ultrasonic sensor or laser distance sensor because of diffusion, refraction or block of light and sound by dense smoke. But, braille blocks that are installed for the visaully impaired at public places such as subway stations can be used as a map for autonomous mobile robot's localization and navigation. In this paper, we developed a laser sensor stan device which can detect braille blcoks in spite of dense smoke and integrated the device to the robot developed to carry out rescue mission in various hazardous disaster areas at KIST. We implemented MCL algorithm for robot's attitude estimation according to the scanned data and transformed a braille block map to a topological map and designed a nonlinear path tracking controller for autonomous navigation. From various simulations and experiments, we could verify that the developed laser sensor device and the proposed localization method are effective to autonomous tracking of braille blocks and the autonomous navigation robot system can be used for rescue under fire.

• 소성∙가공
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• 제16권3호
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• pp.172-177
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• 2007

The process design for large-scale ring rolling of Ti-6Al-4V alloy was performed by calculation method, processing map approach and FEM simulation. The ring rolling design includes geometry design and optimization of process variables. The calculation method was used to make geometry design such as initial billet and blank sizes, and final rolled ring shape. A commercial FEM code, SHAPE-RR was used to simulate the effect of process variables in ring rolling on the distribution of the internal state variables such as strain, strain rate and temperature. In order to predict the forming defects during ring rolling and the formation of over-heating above $\beta$-transus temperature due to deformation heating, the process-map approach based on Ziegler's instability criterion was used with FEM simulation. Finally, an optimum process design to obtain sound Ti-6Al-4V rings without forming defects was suggested through combined approach of Ziegler's instability map and FEM simulation results.

• 대한인간공학회지
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• 제12권1호
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• pp.75-86
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• 1993

Hypermedia systems allow the retrieval and representation of multimedia in- formation such as text, graphics, image and voice/sound using navigation and browsing mechanisms. In this study we developed a hypermedia system which provides hierarchical group, local map and cluster view for effective navigation in hyperspace. The system also supports hot link, reference link, move-to link and multiple link to browse the multimedia information space effectively. This system has been designed to integrate the navigation, browsing and searching function of the hypermedia system in hyman factor perspective and provides the user-friendly user interface mechanism.

• 한국정보통신학회논문지
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• 제10권10호
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• pp.1897-1904
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• 2006

가사도우미 로봇과 같은 서비스 로봇은 가사구성물이 내제된 가정 내 가사 구성물 환경을 인식해야한다. 기존에는 홈서비스 로봇 등은 CCD, 초음파 등의 센서로 가정 내 구성물 및 실내 지형을 인식하였다. 실내지형 지도를 작성 할 경우 가사 구성물에는 헝겊 등이 있는바, 음파 등을 흡수하여 정확한 지형 지도가 만들어지지 못한다. 또한 CCD 카메라를 쓸 경우 pixel에 따라 거리 측정 정도가 달라지는 문제가 발생하고 가격이 고가이다. 본 논문은 이동로봇을 위한 위치 및 물체인식용 지능형 센서 제어 시스템에 대해 기술한다. 개발된 센서제어시스템은 저가의 광 PSD(Position sensitive detector)를 사용하였다. PSD센서의 스위칭 노이즈 및 광 산란에 의한 잡음을 효과적으로 제거하기 위해 로봇의 주행 중 센서 스캔 시 간 등을 고려하여 heuristic software filter를 제안하였다. 또한 개발된 시스템은 초음파 센서에 의한 지형작성 비교와 본 논문에서 개발한 시스템을 비교하였으며, 복잡한 실내지 형을 대상으로 실험 지형지도 작성 실험을 통해 우수성을 입증하였다.

• Spatial Information Research
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• 제6권2호
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• pp.233-245
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• 1998

본 연구는 서울시 1:1,000 수치지형도의 갱신에 필요한 제도적 방안과 다양한 갱신기술 방법들을 비교ㆍ검토하여 서울시 수치지형도의 총체적인 유지관리방안을 수립하는데 목적이 있다. 제도적 방안으로는 서울시 지리정보과(주관부서) 및 사용부서가 동시에 갱신하는 방안과 지리정보과가 당분간 일괄 갱신하는 현실적 대안이 동시에 마련되었다. 또한 갱신 기술방법으로는 도면에 의한 방법과 항공사진을 이용한 수정도화의 방법 등이 최적으로 방법으로 생각되었으며, 장기적으로는 수치정사사진이나 고해상도 인공위성 영상의 활용방법도 필요한 것으로 나타났다. 또한 수치지형도의 유통 및 공급을 위해서는 국립지리원의 공급방침을 바탕으로 서울시의 공급규칙 제정에 필요한 사항들(공급대상, 공급형태, 공급방법, 공급가격 등)이 연구되었다. 본 연구는 1998년 서울시정개발연구원에서 수행한 「서울시 1:1,000수치지형도 유지관리 방안 연구」의 결과이다.

• 말소리와 음성과학
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• 제5권4호
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• pp.171-184
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• 2013

This study investigated the devoicing rate of Japanese high vowels, focusing on regional and generational differences by acoustically analyzing vowels from two large speech databases. The first speech database used in this study was collected between 1986 and 1988 from 41 areas (prefectures) which included 607 participants (299 high school students and 308 their grandparents). The second was taken from a 2006-2007 collection from seven areas as a follow-up investigation to the first database consisting of 463 participants ranging in age from 8-90 year olds. The results revealed there is a generational as well as regional difference in the devoicing rate in almost all areas. Based on those results, a new distribution map reflecting a current devoicing rate of the younger generation was presented. Furthermore, by comparing the two data sets, this study confirmed age difference in the devoicing rate is not age-grading but a sound change in progress. This study discusses the social factors for changes in the devoicing rate of some areas and then applies the devoicing rate of five areas to an S-curve model to predict the future devoicing rate.