• 대한조선학회논문집
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• 제44권5호
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• pp.534-541
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• 2007

This paper suggests the mathematical method for the estimation of the required engine output for WIG crafts. The engine size of a WIG craft Is a key parameter in the design stage, because WIGs should overcome the hump drag during the take-off. Therefore, it is very important for a WIG designer to estimate required power and state change during take-off. The mathematical method was developed based on the steady planing state model of a planing boat. Through numerical calculations on various take-off states, it was found that the suggested method could give reasonable estimation of required power and state change during take-off.

• Ocean Systems Engineering
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• 제4권1호
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• pp.63-82
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• 2014

Declutching control is applied to a hemispherical wave energy converter with direct linear electric Power-Take-Off systems oscillating in heave direction in both regular and irregular waves. The direct linear Power-Take-Off system can be simplified as a mechanical spring and damper system. Time domain model is applied to dynamics of the hemispherical wave energy converter in both regular and irregular waves. And state space model is used to replace the convolution term in time domain equation of the heave oscillation of the converter due to its inconvenience in analyzing the controlled motion of the converters. The declutching control strategy is conducted by optimal command theory based on Pontryagin's maximum principle to gain the controlled optimum sequence of Power-Take-Off forces. The results show that the wave energy converter with declutching control captures more energy than that without control and the former's amplitude and velocity is relatively larger. However, the amplification ratio of the absorbed power by declutching control is only slightly larger than 1. This may indicate that declutching control method may be inapplicable for oscillating wave energy converters with direct linear Power-Take-Off systems in real random sea state, considering the error of prediction of the wave excitation force.

• 한국운동역학회지
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• 제13권3호
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• pp.99-116
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• 2003

The purpose of this study was to kinematics factors on during round-off at end of beam-salto backward stretched with step-out to cross on balance beam. Four elite female gymnastics players participated as subject of this study. The methods of this study was analyzed using three dimentional analysis. The results and conclusion of this paper is obtained as follows ; 1. The phase of time was the most short time in board touch down phase and board take-off phase. Also, it was shown a more long time in total time compared to previous study. 2. The horizontal displacement of each phase was shown the most high levels in balance beam landing. The vertical displacement was display a non-linearity increase in board take-of phase, and it was shown the most high levels in vertical displacement during landing of balance beam. 3. The horizontal velocity of each phase was shown the most high levels in board touch down, and it was display a gradually decreased levels because flight during board take-of. The resultant velocity of CG on each phase was shown the most high levels in board touch down and board take-off. 4. The angle of hip joint was shown the most high levels as performed a motion in extension state during board take-off, and the angle of knee joint was display a increased levels because of flight cause body extension in board take-off. Also the angle of ankle joint was shown a increasing levels during board take-off. Considering to this results, it is suggest that the change of kinematics factors in board touch down and board take-off is key role on the effective board control.

• 제어로봇시스템학회논문지
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• 제12권2호
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• pp.101-105
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• 2006

Disk radial runout creates a periodic relative motion between the laser beam spot and tracks formed on an optical disk. While only focus control is activated, the periodic relative motion yields sinusoid-like waves in the tracking error signal, where one cycle of the sinusoid-like waves corresponds to one track. The frequency of the sinusoid-like waves varies depending on the disk rotational speed and the amount of the disk radial runout. If the frequency of the tracking error signal in the off-track state is too high due to large radial runout of the disk, it is not a simple matter to begin track-following control stably. It might take a long time to reach a steady state or tracking control might fail to reach a stable steady state in the worst case. This article proposes a simple method for reducing the relative motion caused by the disk radial runout in the off-track state. The relative motion in the off-track state is effectively reduced by a drive input obtained through measurements of the tracking error signal and simple calculations based on the measurements, which helps reduce the transient response time of the track-following control. The validity of the proposed method is verified through an experiment using an optical disk drive.

• International Journal of Aeronautical and Space Sciences
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• 제17권1호
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• pp.120-131
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• 2016

The full results of troubleshooting process related to the flight control system of a tilt-rotor type UAV in the flight tests are described. Flight tests were conducted in helicopter, conversion, and airplane modes. The vehicle was flown using automatic functions, which include speed-hold, altitude-hold, heading-hold, guidance modes, as well as automatic take-off and landing. Many unexpected problems occurred during the envelope expansion tests which were mostly under those automatic functions. The anomalies in helicopter mode include vortex ring state (VRS), long delay in the automatic take-off, and the initial overshoot in the automatic landing. In contrast, the anomalies in conversion mode are untrimmed AOS oscillation and the calibration errors of the air data sensors. The problems of low damping in rotor speed and roll rate responses are found in airplane mode. Once all of the known problems had been solved, the vehicle in airplane mode gradually reached the maximum design speed of 440km/h at the operation altitude of 3km. This paper also presents a comprehensive detailing of the control systems of the tilt-rotor unmanned air vehicle (UAV).

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.97-101
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• 2000

The AE measurement is one of the most convenient methods for detecting contacts between slider disk. The AE method has been widely used in the investigation of the tribology of sliding interfaces due to the convenience of using AE sensor. In this study, we examined the relationship between the AE signal and the flying height of a slider. We tried to know the influence of the disk velocity on the AE rms signal by using the AE measurement system. The experiment also gives the relationship between the take-off velocity and the disk surface state. To investigate the behavior of the slider further, the variances of the AE signal are analyzed. The results about a subambient pressure slider indicate that the increase in the magnitude of AE rms signal does not necessarily mean the slider/disk contacts.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 춘계 학술대회논문집
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• pp.14-19
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• 2005

The paper introduces the state-of-the art of WIG ship and application field of the CFD to WIG ship development. WIG ships are highly efficient and fast transport vehicles which take advantage of benefits of ground effect. Chapter 1 describes the characteristics of WIG ship. Chapter 2 reviews the research works of Russia, German, Chinese, Korea and etc. Chapter 3 explains the kind of WIG ship categorized by the main operational mode and take-off system. Chapter 4 describes about the application field of CFD to WIG ship development procedure.

• 대한전자공학회논문지TC
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• 제48권1호
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• pp.97-101
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• 2011

개인 휴대통신의 서비스 대역에 대응하는 4중 대역 p-HEMT SP6T 스위치를 구현하였다. 낮은 삽입손실과 높은 격리특성을 달성하기 위하여, 트랜지스터 단위소자의 최적화를 통해 On-Off간 상호 보완적 관계를 고려하였으며, 특히 송수선간 격리 특성의 경우, 큰 커패시터 삽입을 통하여 우수한 격리 특성을 달성하는 동시에 단일의 전압제어와 백비아를 사용한 접지를 통해 소형화를 달성하였다. 구현된 SP6T 스위치는 $950um{\times}100um$의 크기를 가지며 공정상 게이트 우물의 오류를 감안할 때, 각 주파수 대역에서 우수한 삽입손실 및 격리특성을 확인 할 수 있었다.

• 기본간호학회지
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• 제26권2호
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• pp.136-143
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• 2019

Purpose: The feasibility and differential effects of two music therapy methods (interventions with preferred music vs. classical relaxation music) were done to examine the effects on agitation and anxiety in patients weaning off mechanical ventilation. Methods: This pilot study was conducted using a crossover design. Six patients listened to preferred music choices and classical relaxation music. Anxiety scores were measured using the Richmond Agitation Sedation Scale (RASS), State-Trait Anxiety Inventory (STAI), and visual analog scale (VAS). Results: Patients showed a significant decrease in agitation and anxiety after both the preferred and classical relaxation music interventions. The difference in the effects of preferred music and that of classical relaxation music was not significant. As for feasibility, patients exhibited a change in agitated behaviors after the music interventions by not trying to take off medical devices and quietly listening to the music, and by smiling and moving lips along with the lyrics while listening. Conclusion: Music interventions which centered on either patients' preferences or classical relaxation music to enhance relaxation, helped reduce agitation and anxiety during the mechanical ventilation weaning process.

• 한국재난정보학회 논문집
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• 제16권1호
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• pp.44-59
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• 2020

이 논문에서는 2층 건물 지하층의 다방에서 가스냄새가 난다고 119신고가 되어 소방대원들이 출동하여 옥상에 있는 LPG 가스통들의 밸브를 직접 잠그고 지하층 다방의 중간밸브의 잠금 상태를 확인하고 현장에 도착한 가스공급 및 설치 업자에게 안전조치를 취하도록 요구하고 철수한 후 7분 만에 가스폭발사고가 발생하여 2명이 사망하고 21명이 부상을 입은 사례를 분석하고 있다. 법원은 가스폭발사고의 원인이 규명되지 아니하였으므로 가스공급 및 설치 업자와 한국가스안전공사에 배상 책임을 물을 수 없고 안전조치를 하지 않고 철수한 소방기관에게만 배상책임이 있다고 판결하였다. 그러므로 가스가 누설된다고 119신고가 되는 경우에 출동한 소방대는 가스 밸브를 잠그고 사람들을 대피시키거나 접근하지 못하게 하고 환기를 시키는 등 안전조치를 하고 화재나 폭발가능성이 없음을 확인한 후 철수해야 한다.