• 한국정보통신학회논문지
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• 제25권4호
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• pp.611-614
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• 2021

In this paper, we propose a widerange array microphone for lecturer tracked with Frequency Modulated Continuous Waveform (FMCW) radar sensor. Time Difference-of-Arrival (TDoA) is often used as audio tracking, but the tracking accuracy is poor because the frequency of the voice is low and the relative frequency change is large. FMCW radar has a simple structure and is used to detect obstacles for vehicles, and the resolution can be archived to several centimeter. It is shown that the sensor is useful for detecting a speaker in open area such as a lecture, and we propose an wide range 4-element array microphone beamforming system. Through some experiments, the proposed system is able to adequately track the location and showed a 8.6dB improvement over the selection of the best microphone.

• 생물정신의학
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• 제30권1호
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• pp.7-16
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• 2023

Objectives This study aimed to review the Korean Constitution articles 14 and 20 of the "Law on suicide prevention" and investigate public perceptions of specific improvements to suicide prevention policies using results from the Korean 2018 National Survey on Suicide. Methods The questionnaire was designed to analyzing the act restricts sharing of patient information between hospitals, making it difficult to track suicide attempts. The questionnaire was also designed to suggest further medical and normative criteria for objective judgment of continuous follow-up utilizing suicide risk evaluations and proportional principle review that consider patients' and medical staff's basic rights. Results This study identified the result of the 1500 respondents, 79.1% believed that Korea should allow suicide prevention management to be implemented without requiring individual consent to protect suicide attempters. Conclusions According the results, I propose the following criteria for policy improvement: use of anonymized information and non-profit research for technical and ethical considerations, access to medical information only for therapeutic purposes, and use of surgical severity assessment criteria appropriate for Korea.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집(한일합동학술편); 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.926-931
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• 1987

The present study is devoted to the development of a simplified teaching method whereby the control data of the 3-dimensional operations of a playback-type trial robot can be stored in a personal computer. The control data of the 3-dimensional operations are given using an instruction wand handled by an operator. The operator's task is only to track a desired robot path with the wand. The 3-dimensional position of the wand are measured by ultrasonic devices, the principle of which was developed for this study and is introduced in detail. In order to clarify the applicability of this method, experts were performed with respect to a continuous-path teaching and a pick-and-place task teaching which are typical jobs of robot operators.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.49-50
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• 2015

Since the mid-2000s, Korean large-sized construction companies have pursued in earnest to expand their business to global construction market in surroundings that domestic market have a continuous and long-term stagnation. However, during last a few years, they have experienced the serious financial loss from international projects. In the meantime, for the sound improvement of Korean construction industry, many stakeholders long for efficient early warning signals to generally monitor and track the potential risks of international projects. In this study, we introduce an International Project Risk Index (IPRI), which is derived from massive data provided by large-sized companies, and expect to provide the practitioners and decision makers as an aid to proactively cope with the change of the potential risks. The outcomes from the IPRI can be utilized to prepare a timely management strategy and to establish an appropriate government support regulation.

• International Journal of Internet, Broadcasting and Communication
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• 제16권2호
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• pp.87-92
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• 2024

The rapid development of artificial intelligence technology in recent years is evident, from the emergence of ChatGPT to innovations like Midjourney, Stable Diffution, and the upcoming SORA text-to-video technology by OPENai. Animation capture technology, driven by the AI technology trend, is undergoing significant advancements, accelerating the progress of the animation industry. Through an analysis of the current application of DEEPMOTION, this paper explores the development direction of AI motion capture technology, analyzes issues such as errors in multi-person object motion capture, and examines the vast prospects. With the continuous advancement of AI technology, the ability to recognize and track complex movements and expressions faster and more accurately, reduce human errors, enhance processing speed and efficiency. This advancement lowers technological barriers and accelerates the fusion of virtual and real worlds.

• 한국전자파학회논문지
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• 제21권11호
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• pp.1304-1310
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• 2010

낮은 고도로 접근하는 고속 표적을 탐지 및 추적하기 위해 사용하는 K 대역의 FMCW(Frequency Modulated Continuous Wave) 레이다의 송수신기 설계 방법을 제안한다. 송신기는 레이다 유효 반사 면적(RCS : Radar Cross Section)이 작은 표적의 추적 및 넓은 송신 안테나 빔 폭으로 인해 고출력이 요구되며, 수신기의 경우는 인터페로메타 방법을 이용하여 표적을 추적하기 위해 다채널 수신기가 요구된다. 송신기는 고출력 송신 증폭기와 도파관 스위치 및 주파수 상향 변환 기판으로 구성된다. 수신기는 5 채널 수신기, 중간 주파수 상향 및 하향 변환 모듈, X 대역 국부 발진기 및 파형 발생 모듈로 세분화 할 수 있다. 제안한 구조를 제작하기 전에 모델링 및 시뮬레이션 방법을 통해 여러 파라메타를 측정함으로써 가능성을 입증한다. 그리고 제안한 송수신기를 산업용 부품을 사용하여 제작하고 성능 파라메타를 측정하였다. 그 결과, 송신기 출력은 39.64 dBm, 수신기 이득은 29.1 dB이며, 그 외 모든 설계 요구 조건을 만족함을 입증하였다.

• 대기
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• 제30권3호
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• pp.209-220
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• 2020

Seasonal predictability and variability of tropical storms (TCs) simulated in the Global Seasonal Forecast System version 5 (GloSea5) of the Korea Meteorological Administration (KMA) is assessed in Northern Hemisphere in 1996~2009. In the KMA, the GloSea5-Global Atmosphere version 3.0 (GloSea5-GA3) that was previously operated was switched to the GloSea5-Global Coupled version 2.0 (GloSea5-GC2) with data assimilation system since May 2016. In this study, frequency, track, duration, and strength of the TCs in the North Indian Ocean, Western Pacific, Eastern Pacific, and North Atlantic regions derived from the GloSea5-GC2 and GloSea5-GA3 are examined against the best track data during the research period. In general, the GloSea5 shows a good skill for the prediction of seasonally averaged number of the TCs in the Eastern and Western Pacific regions, but underestimation of those in the North Atlantic region. Both the GloSea5-GA3 and GC2 are not able to predict the recurvature of the TCs in the North Western Pacific Ocean (NWPO), which implies that there is no skill for the prediction of landfalls in the Korean peninsula. The GloSea5-GC2 has higher skills for predictability and variability of the TCs than the GloSea5-GA3, although continuous improvements in the operational system for seasonal forecast are still necessary to simulate TCs more realistically in the future.

• 한국철도학회논문집
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• 제11권3호
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• pp.326-333
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• 2008

본 논문은 누적통과톤수에 의한 레일교체기준 개정을 위한 기초 데이터를 제시하는데 목적이 있다. 본 연구에서는 국외의 누적통과톤수에 의한 레일교체기준의 산정근거를 조사하였으며, 일본에서 조사된 레일용접부 결합유형 및 원인과 국내 철도운영기관인 서울메트로의 궤도유지관리이력을 조사하여 실제 레일절손과 누적통과톤수의 상관관계를 분석하였다. 또한, 누적통과톤수 기준치에 도래한 노후레일 용접부를 현장에서 발췌하여 레일용접부 휨시험을 수행하였다. 그 결과, 누적통과톤수와 레일절손간의 상관관계는 뚜렷하지 않았으며 레일용접부의 시공불량에 의한 절손사례가 많은 것으로 분석되었다. 또한, 노후레일휨시험 결과 신규레일용접부에 비해 파괴강도가 $17{\sim}18%$만이 저하된 것으로 나타나 레안교체기준에 도래한 노후레일은 사용성 측면에서 충분한 내구성 및 내하력을 확보하고 있는 것으로 분석되었다.

• Tribology and Lubricants
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• 제34권6호
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• pp.217-225
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• 2018

In this study, we spray a Ni-Cr composite powder onto AISI 4340 steel using the high velocity oxygen fuel method. We subsequently subject the Ni-Cr coating (as-sprayed) to ultrasonic nanocrystal surface modification (UNSM) process to improve the tribological performance. This study aims at increasing the wear resistance and durability of the Ni-Cr coating by altering the surface integrity and microstructure via the UNSM process. The UNSM process reduces the surface roughness of the as-sprayed coating by about 64%, which is explained by observing the elimination of high peaks and valleys and filling up micro-pores. Furthermore, a change in the microstructure of the coating due to continuous high-frequency strikes to the surface by a tip can lead to an increase in hardness from about 48 to 60 HRC. Furthermore, we investigate the characterization of the friction and wear behavior of Ni-Cr coating by a ball-on-disc tribometer in the dry conditions. We determine that after the UNSM process, there is a significant reduction in the friction coefficient of the as-sprayed coating from approximately 1.1 to 0.75. This is owing to the increased hardness and smoothed surface roughness. In addition, we investigate the surface morphology and wear track of the coatings before and after the UNSM process using a scanning electron microscope, energy dispersive spectrometer, and three-dimensional laser scanning microscope. We observe that the wear track of the Ni-Cr coating after the UNSM process is lower than that of the as-sprayed one. Thus, we confirm that the UNSM process has a significant influence on the improvement of the tribological performance of the Ni-Cr composite coating.

• 한국분말재료학회지
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• 제29권5호
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• pp.390-398
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• 2022

Recently, considerable attention has been given to nickel-based superalloys used in additive manufacturing. However, additive manufacturing is limited by a slow build rate in obtaining optimal densities. In this study, optimal volumetric energy density (VED) was calculated using optimal process parameters of IN718 provided by additive manufacturing of laser powder-bed fusion. The laser power and scan speed were controlled using the same ratio to maintain the optimal VED and achieve a fast build rate. Cube samples were manufactured using seven process parameters, including an optimal process parameter. Analysis was conducted based on changes in density and melt-pool morphology. At a low laser power and scan speed, the energy applied to the powder bed was proportional to ${\frac{P}{\sqrt{V}}}$ and not ${\frac{P}{V}}$. At a high laser power and scan speed, a curved track was formed due to Plateau-Rayleigh instability. However, a wide melt-pool shape and continuous track were formed, which did not significantly affect the density. We were able to verify the validity of the VED formula and succeeded in achieving a 75% higher build rate than that of the optimal parameter, with a slight decrease in density and hardness.