• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.83-83
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• 2003

자기 폭풍 발생시에 지구 자기권 내에서 MeV 에너지대의 전자 플럭스가 증가하는 현상이 나타남이 관측되었다. 이러한 Relativistic Electron Events (REE) 가속 기작의 주요 후보로 Ultra-Low Frequency(ULF)와 whistler 파동의 역할이 제시되어왔다. 본 연구에서는 1997부터 1999년에 발생한 대표적인 자기 폭풍들을 선택하여, 상대론적 전자 플럭스가 증가한 경우, 감소한 경우 그리고 변화가 크게 나타나지 않는 경우의 세 가지로 분류하여 보았다. 각각의 event들에 대해 CANOPUS 지상자기장 관측소에서 얻은 지자기 값을 이용하여 위 각각의 세 경우에 대해 ULF 파동의 크기 변화를 비교해 보았다. 그리고 똑같은 자기 폭풍 현상에서 POLAR 위성의 관측 값을 이용하여 whistler 영역의 파동 강도를 살펴보았다. 또한 자기 폭풍과 REE, 그리고 ULF의 변화가 L-shell값과 어떤 관련이 있는지도 알아본다.

• The Optical Journal
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• s.140
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• pp.47-53
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• 2012

초고출력 레이저와 비선형광학에 대한 고찰이다. 초단펄스를 발생하는 광 스위치의 역사, 비선형광학결정에 의한 파라메트릭증폭, 하전입자를 가속하는 상대론광학, 레이저확대법칙의 역사적 전환, 초고출력 레이저에 의한 고에너지물리학 등에 대해서 기술하고 있다. 이것들을 통해 보면 광 강도가 강하게 됨에 따라 최초는 선형응답에서 시작하는 상호작용에서 비선형효과가 발생하고, 그리고 비선형광학이 발전하면 오히려 비선형광학에서 만들어지는 선형상호작용, 예를 들면 상대론광학과 초상대론광학 등에 의해 종래, 비선형에서 소프트한 상태 중에 질서 된 관계가 만들어지듯이 선형${\rightarrow}$비선형${\rightarrow}$선형${\rightarrow}$비선형${\rightarrow}$선형을 반복하는 것을 알 수 있다. 본고는 전기통신대학 레이저신세대연구센터 우에다 켄이치 연구원이 월간 광기술 컨텍트 2012년 5월에 기고한 내용으로서 그린광학의 유정훈 팀장이 번역에 도움을 주었다.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.3
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• pp.125-130
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• 1992

A digital 6-dof motion measuring system is developed using 7 accelerometers following Miles'[1] method. A snoic wave height gauge is also developed to measure the relative wave height at the foremost end of the ship. By combining the time series of both 6-dof motions and relative wave height, we can estimate the time series of real sea wave. Results of model tests shows the validity of the developed system.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.903-908
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• 1998

KALIMER 원자로 건물에 대하여 3차원 쉘요소 모델과 단순 빔모델을 작성하고 고유진동수 해석을 수행하였다. 두 모델의 1차 수평방향 고유진동수는 대체로 일치하였다. 단순 빔모델에 대해 원자로건물의 회전 관성모멘트를 해석에 반영한 경우 3차원 모델에는 없는 회전모드가 발생되었다. 지진응답해석은 1940 EL Centro와 인공지진에 대하여 수행하였으며, 두 결과는 면진구조물의 경우 비면진구조물과 비교하여 응답가속도가 크게 줄고, 상대변위가 증가하는 경향을 보였다.

• Magazine of the Korea Concrete Institute
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• v.14 no.4
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• pp.56-58
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• 2002

$\ulcorner$콘크리트표준시방서$\lrcorner$ 에서는 "서중 콘크리트로서 시공해야 할 시기를 일률적으로 정하기는 곤란하나, 하루평균 기온이 $25^{\circ}C$ 또는 최고온도가 3$0^{\circ}C$를 초과하는 시기에 시공할 경우에는 일반적으로 서중 콘크리트로서 시공할 수 있도록 준비해 두어야 한다."고 규정하고 있고, $\ulcorner$ACI 305R$\lrcorner$ 에서는 "서중(hot weather)은 수분 손실률과 시멘트 수화율의 가속에 의하여 굳지 않은 콘크리트(fresh concrete)와 굳은 콘크리트(hardened concrete)의 품질을 저하시키는 다음 조건들이 공존하는 상태이다."고 규정하고 있으며 그 조건들은 a. 높은 대기 온도 b. 높은 콘크리트 온도 c. 낮은 상대습도 d. 바람의 세기(풍속) 이다.(중략)

• Geotechnical Engineering
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• v.12 no.6
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• pp.5-20
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• 1996

This paper presents results from a series of model tests on laterally loaded single piles with both free-head and free-tip conditions. Model tests, using a centrifuge apparatus (middie size, Mark II in 7.1.7.) were carried out in sand based on the variation of different gravity acceleration and flexural stiffness of the pile and relative density of the soil. The aims of this study are to estimate the effect of gravity acceleratioil, flexordis stiffness, and relative density on the behavior of the pile embedded in Toyoura sand and to evaluate the applicability of a family of the p-y curves which was presented by several reseachers(Mur chison & O'Neill, neese et n., scott, Det worske veritas, nondner). The Program is deviloped by using p-y curves, and it can be used for the calculation of the displacement distri bution, bending moment distribution, and soil reaction distribution. By comparing meas ured responses with predicted one it is shown that the results of the p-y curve equation presented by Murchison & O'Neill and Kondner agreed with the general trend observed by the centrifuge tests much better than the numerical solutions predicted by the other sets of p -y curves.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.1
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• pp.114-120
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• 2013

Recently, navigation systems based on wireless communication have been applied to the internal structures such as building or ship. If a stable azimuth information is obtained, these systems can effectively guide the direction of the user's progress through the information and then can improve the performance of guidance. Since conventional method which has acquired an azimuth information using geomagnetic and acceleration sensor(azimuth sensor hereafter) is sensitive to the effects of the magnetic field, it has unstable error range according to the surrounding environment. In order to improve these problems, this paper presents a new relative azimuth estimation algorithm using the displacement of a mobile node and its rotation angle based on Wireless communication. For the performance assessment of the proposed algorithm, experiments using rotating arm are performed and the results are confirmed that the proposed system can estimate the relative azimuth without using additional sensors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.3112-3118
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• 2010

The pH control agent in PWRs, to insure the integrity of steam generator, was changed from ammonia to ethanolamine(ETA) which decreased pH at condensate system and low pressure feedwater heater drain system, so that several amines were investigated for the selection of the optimum amine. There was no single alternative amine to meet the optimum condition. The more volatile ammonia provides the higher pH in condensate, while the less volatile ETA increases the pH in wet steam area. Thus, the combined amine of ammonia and ETA is able to equally raise the pH in both region so that the flow accelerated corrosion be reduced in the every system of the secondary side and the integrity of steam generator be also improved in pressurized water reactors (PWRs).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.842-850
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• 2014

This paper presents a trajectory tracking controller for rotorcraft UAVs to improve the tracking performances in the presence of various uncertainties. The proposed tracking method consists of a velocity guidance law based on the relative distance and L1 adaptive augmentation loop for tracking the velocity commands. In the proposed structure, the desired velocity generated by the guidance law is the reference value of the adaptive controller for accurate path tracking. In the guidance law, the desired acceleration is generated based on the relative distance and its derivatives, and then the velocity command of the inner control loop is calculated by integrating the accelerations. $L_1$ augmentation loop supplements the linear controller to guarantee the flight performances such as a tracking accuracy in the presence of the uncertainties. The proposed controller was validated in actual flight tests to successfully demonstrate its capability using a quadrotor UAV.

• Radiation Oncology Journal
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• v.21 no.2
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• pp.167-173
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• 2003

Purpose: The purpose of this study was to evaluate whether a GafChromic film applied to stereotactic radiosurgery with a linear accelerator could provide information on the value for acceptance testing and quality control on the absolute dose and relative dose measurements and/or calculation of treatment planning system. Materials and methods: A spherical acrylic phantom, simulating a patient's head, was constructed from three points. The absolute and relative dose distributions could be measured by inserting a GafChromic film into the phantom. We tested the use of a calibrated GafChromic film (MD-55-2, Nuclear Associate, USA) for measuring the optical density. These measurements were achieved by irradiating the films with a dose of 0-112 Gy employing 6 MV photon. To verify the accuracy of the prescribed dose delivery to a target isocenter using a five arc beams (irradiated in 3 Gy per one beam) setup, calculated by the Linapel planning system the absolute dose and relative dose distribution using a GafChromic film were measured. All the irradiated films were digitized with a Lumiscan 75 laser digitizer and processed with the RIT113 film dosimetry system. Results: We verified the linearity of the Optical Density of a MD-55-2 GafChromic film, and measured the depth dose profile of the beam. The absolute dose delivered to the target was close to the prescribed dose of Linapel within an accuracy for the GafChromic film dosimetry (of $\pm$3$\%$), with a measurement uncertainty of $\pm$1 mm for the 50$\~$90$\%$ isodose lines. Conclusion: Our results have shown that the absolute dose and relative dose distribution curves obtained from a GafChromic film can provide information on the value for acceptance. To conclude the GafChromic flim is a convenient and useful dosimetry tool for linac based radiosurgery.