• 지구물리와물리탐사
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• 제14권1호
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• pp.69-79
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• 2011

본 연구에서는, 필리핀의 마닐라에서 관측된 지진 기록을 통해 얇고 깊은 토양층의 S파 속도 구조와 경험적 현장 증폭 특성을 평가하였다. 지진 기록에 빛띠 역산법 (Spectral inversion technique)을 적용하여 진원, 경로 및 국지적 현장 증폭 효과들을 평가하였다. 사용한 지진 자료는 36회의 중간급 지진들의 기록을 얻었으며, 그 중에서 마닐라의 지진 관측 망에서 강한 움직임을 보인 10곳의 관측점 자료를 이용하였다. 전파경로의 추정 Q값은 54,6f 1.1으로 모사된다. 대부분의 진원의 빛띠(스펙트럼)는 오메가-스퀘어 (omega-square) 모형으로 근사 될 수 있다. 현장 증폭 특성은 지표 지질조건에 따라 특유의 특정을 보여준다. 중앙 고지대의 증폭특성은 우세 주파수를 갖지 않는데 비해, 해안 저지대 와 마리카나(Marikina) 계곡에서의 증폭특성은 1~5Hz의 우세 주파수를 갖는다. 우리는 현장 증폭 특성을 S파 속도로 변환한 후에, 증폭 특성과 상부 30m의 평균 S파 속도 구조와의 관계를 검토하였다. 낮은 주파수대의 증폭 특성은 평균 S파 속도와 좋은 상관성을 보인다. 반면, 높은 주파수대의 증폭특성은 상부 30m내의 평균 S파 속도로 충분히 설명되지 않는다. 이것은 30m보다 낮은 심도의 평균 S파 속도와 더 많이 관련되어 있다.

• 한국해안·해양공학회논문집
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• 제22권1호
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• pp.10-17
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• 2010

투과성 이중 반원통 구조물과 경사 입사파간의 상호작용문제를 선형포텐셜 이론을 사용하여 살펴보았다. 투과성 이중 반원통 구조물은 바닥에 고정된 동심원상으로 배열된 2개의 원통 구조물로 이루어지며 각 원통 구조물의 전면은 일정한 공극율을 갖는 투과벽으로 후면은 투명한 벽으로 구성된다. 전면 투과벽의 공극율과 간격 그리고 파랑특성(주파수, 입사각)을 변화시키면서 파랑하중과 처올림 파형 그리고 파 차단성능을 살펴보았다. 파 차단 성능의 척도로서 차단영역내의 평균제곱 변위의 제곱근(R.M.S.)을 사용하였다. 투과성 반원통 구조물은 불투과성 구조물과 비교하여 차단영역내의 파도응답을 감소시키며 구조물에 작용하는 파랑하중을 크게 줄여준다. 특히 이중 구조물은 고주파주 영역에서 단일 구조물보다 파를 차단하는데 효과적이다.

• Journal of Welding and Joining
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• 제20권1호
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• pp.76-82
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• 2002

In these days, many advanced nations have enforced import restrictions against things emitting electromagnetic wave which has report that it is so harmful. In general, electromagnetic wave is composed of electric wave and magnetic wave. The reflection of electromagnetic wave is mainly reflected by conductive materials and the magnetism loss is generated by magnetic ferrite. The magnetism loss of ferrite is separated by eddy current loss, residual magnetism loss and hysteresis loss. Thermal sprayed coating is intended to manufacture because of simple processes and high efficient electromagnetic wave shielding. The high efficient thermal sprayed coatings were made from the magnetic ferrite materials that characterizes absorption of electromagnetic wave, and the electric conductive materials that characterize emitting of electromagnetic wave. This study was manufactured thermal sprayed coatings to improve absorption-efficiency, and measured the electromagnetic wave shielding efficiency. As the experimental results, high electromagnetic wave shield efficiency was obtained at wave frequency 2GHz to thermal sprayed ferrite coatings manufactured by size distribution range of spray powders, $38~88\mu\textrm{m}$.

• The Journal of the Acoustical Society of Korea
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• 제22권4E호
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• pp.167-175
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• 2003

Shear wave velocity was measured and grain size analysis was conducted on two core samples obtained in unconsolidated marine sediments of the western continental margin, the East Sea. A pulse transmission technique based on the Hamilton frame was used to measure shear wave velocity. Duomorph ceramic bender transducer-receiver elements were used to generate and detect shear waves in sediment samples. Time delay was calculated by changing the sample length from the transducer-receiver element. Time delay is 43.18 μs and shear wave velocity (22.49 m/s) is calculated from the slope of regression line. Shear wave velocities of station 1 and 2 range from 8.9 to 19.0 m/s and from 8.8 to 22 mis, respectively. Shear wave velocities with depth in both cores are qualitatively in agreement with the compared model〔1〕, although the absolute value is different. The sediment type of two core samples is mud (mean grain size, 8-9Φ). Shear wave velocity generally increases with sediment depth, which is suggesting normally consolidated sediments. The complicated variation of velocity anisotropy with depth at station 2 is probably responsible for sediment disturbance by possible gas effect.

• Ocean Systems Engineering
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• 제10권2호
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• pp.131-161
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• 2020

The objective of this study was to evaluate the downtime cost of side-by-side offloading operations in Malaysian waters. With the help of a numerical time domain tool, the structure and cable response of moored FPSO vessel was simulated for heading and beam sea-states under irregular waves. The weather downtime was assessed by comparing the response under operational wave condition with the pre defined industrial safe offloading criteria. Additionally, two cases of cable failure were simulated for each sea-state. The novel study on downtime cost was presented for three different location of Malaysia subcontinent for which the location specific wave scatter diagram facilitated to estimate the probability of occurrence of operational wave condition. It was concluded that an unpredictable increment in wave height by 0.5 m can significantly impact the production cost.

• 대한화학회지
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• 제6권2호
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• pp.108-112
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• 1962

Lead ion gives a well-defined wave with $E_{1/2}$=-0.57V(vs. S.C.E.) from a base electrolyte consisting of 0.1M TEA=0.5M$KNO_3$=0.0002% methl red. (pH 9.8).The reduction wave of lead is lead(II) to lead(0) and electrode reaction of this wave diffusion controlled.Its diffusion current constant is 2.45 and temperature coefficient of this wave is about 1.2%.Under above conditions, diffusion current is proportional to the concentration of lead in the range of $10^{-3}$ ~$10^{-4}$ M.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.141-144
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• 2004

Nowadays, there has been substantial interest in whether there is an association between electromagnetic field exposure and living environment. It is increased the demand that electromagnetic wave environment and its countermeasure. In the present study, we has applied the electromagnetic absorbent inorganic paint of 'I' corporations, and measured electromagnetic waves generated in new apartment before occupancy using the standard field electromagnetic wave generating device we developed. The measurement before occupancy was $100\~131V/m$, but the measurement after occupancy was $6.9\~8.0V/m$ less than 10V/m, the comprehensive electromagnetic wave limit allowed by TCO in Sweden. The implication is that domestic apartment are exposed to extremely poor electromagnetic wave environment. Nevertheless, there have been neither serious efforts to overcome this problem, nor its alternatives and related standards. Therefore, it is necessary to continue research of related fields to establish standards and plans to improve the situation.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1997년도 정기학술강연회 발표논문 초록집 Annual Meeting of Korean Society of Coastal and Ocean Engineers
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• pp.135-138
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• 1997

The interaction of oblique monochromatic incident waves with a horizontal flexible membrane is investigated in the context of two-dimensional linear hydro-elastic theory. First, analytic diffraction and radiation solutions for a submerged impermeable horizontal membrane are obtained. Second, the theoretical prediction was compared with a series of experiments conducted in a two-dimensional wave tank at Texas A&M University. The measured reflection and transmission coefficients reasonably follow the trend of predicted values. Using the developed computer program, the performance of surface-mounted or submerged horizontal membrane wave barriers is tested with various system parameters and wave characteristics. It is found that the properly designed horizontal flexible membrane can be an effective wave barrier and its efficiency can be further improved using a porous material.

• 한국해양공학회지
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• 제16권2호
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• pp.10-20
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• 2002

본 논문에서는 바다의 자유표면에서 생성되는 항력에 대한 물리적 특성에 대한 연구가 기술되었다. 2차원 파장(Wave Field) 매개변수해석기법(Parametric Analyzing Technique)을 근거로 한 파경계층(Wave Boundary Layer : WBL)의 1차원 모델로서 항력계산과 파경계층의 특성을 추정하였으며 이론의 간략화(Simplifying)에 대한 연구에 주력하였다.

• 대한임상전기생리학회지
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• 제9권2호
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• pp.19-24
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• 2011

Purpose : This study is to examine the effects of transcranial direct current stimulation on the excitability of the central neuron. Methods : This study selected 24 suitable women in their twenties. A positive electrode of transcranial direct current stimulation was placed on the primary motor area (M1) C4 and a negative electrode was placed on the left supraobital. A stimulation of 0.04mA/$cm^2$ was applied for 20 minutes. H-reflex and V wave used diagnostic electromyography. An active electrode was placed at the muscle belly of the medial gastrocnemius muscle at a prone posture. An electrical stimulation was given to the posterior tibial nerve. Measurements were made before and after the stimulation. All data were analyzed with SPSS 12.0 and between each measuring before and after the change of the H-reflex and V wave amplitude. Results : There were no significant differences in all H wave, M wave, and V wave amplitude before and after transcranial direct current stimulation. There were no significant differences in the change of H/M ratio and V/M ratio before and after transcranial direct current stimulation. Conclusion : We know that transcranial direct current stimulation cannot have an influence on a normal grown-up person's central neuron.