• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2068-2070
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• 2000

Ground potential rise is a vital part of personal safety, this paper presents the ground potential rise distribution induced by a ground rod. The experiments were conducted with the AC square wave currents according to the buried depth of ground rod. The ground potential is significantly varied in the vicinity of ground rod and the ground potential distribution is flat and few with increasing the buried depth of ground rod.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1998년도 정기학술강연회 발표논문 초록집 Annual Meeting of Korean Society of Coastal and Ocean Engineers
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• pp.65-71
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• 1998

유조선의 빈번한 왕래로 발생되는 원유의 누출사고, 무절제한 해안환경 파괴 및 생활하수, 공장폐수의 방류 문제가 최근 대중매체를 통하여 빠짐없이 보도되고 있으며 또 그로 인하여 양식장, 바다낚시, 해수욕장 등 생산 및 생활 환경이 오염되어 일반인들도 직접 간접으로 적지 않게 피해를 입게 되므로 그에 대한 관심이 날로 증가되고 있다. 동해 어항의 경우는 수산물 가공폐수 외에 주변에 주거지 및 상가(횟집) 등이 위치하여 생활오수 등이 다량 발생하고 있다. (중략)

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2000년도 한국해안해양공학발표논문집 Proceedings of Coastal and Ocean Engineering in Korea
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• pp.140-148
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• 2000

The nearshore currents are required for the preservation of coastal areas and the more pressing environmental problems since they cause sediments to be in suspension and transport the sediments into tranquil regions. Numerical models are often used to calculate current patterns formed around man-made or naturally caused changes around the coastal area. (omitted)

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1992년도 춘계학술대회
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• pp.213-217
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• 1992

An inductively coupled magnetical signal (pulse wave, 0.7 to 60Hz, eighteen volts peak to Peak) that was applied non-invasively on the skin surface overlying the approximate site(measure position). In the group with unipolar pulse signal currents produced smaller than in the group with bipolar pulse signal. The signal was transmitted to the active coil, including a time-varying magnetic field: this in turn induced a the-varying electrical field in the field in the bone. It is very important to determine system parameters due to treatment time(healing) and the simplicity. This paper investigation was designed to compare the relative effects of pulsed unipolar currents with the effects of an identical pulsed bipolar currents. Since Inductive coupling is non-invasive and involves portable equipment, it is easy to apply and requires precise localization, it has distinct advantages and field characteristics along the bone for each different signal.

• 한국군사과학기술학회지
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• 제14권2호
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• pp.189-197
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• 2011

As a multidisciplinary study encompassing oceanography and history, we have attempted to reanalyze the course of a historical navel battle, Myungryang Naval Battle(September 16th, 1597 according to the lunar calendar) through hindcasting the paleo-tidal currents and -tides(PTC). Firstly, we conducted harmonic analysis using 6-month current data observed at Uldolmok and 1-year elevation data provided by Korea Ocean Research and Development Institute in order to understand their characteristics and to hindcast the PTC. Observation results show that Uldolmok, ~300m wide, relatively narrow channel, is characterized by a flood-dominant mixed mainly semidiurnal tidal regime induced by relatively-strong shallow water constituents, showing closely a standing wave type of tidal current. Further, we hindcasted PTC on the day of Myungryang Naval Battle. Our results were compared and discussed with results(time and speeds of maximum(flood and ebb) currents and high and low water times) of the previous studies estimated from different methods. Lastly, we reconstruct the course of the event of Myungryang Naval Battle recorded in the Admiral Sun-Sin Yi's War Diary(Nangjung Iigi in Korean) based on our hindcasting results.

• International Journal of Aeronautical and Space Sciences
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• 제16권3호
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• pp.339-346
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• 2015

Aerodynamic flow control phenomena were investigated with a low-current DC surface discharge plasma actuator. The plasma actuator was found to operate in three different discharge modes with similar discharge currents of about 1 mA or less. Stable continuous DC discharge without audible noise was obtained at higher ballast resistances and lower discharge currents. However, even with continuous DC power input, a low-frequency self-pulsed discharge was obtained at lower ballast resistances, and a high-frequency self-pulsed discharge was obtained at higher set-point currents and higher ballast resistances, both with audible noise. The Schlieren image reveals that the low-frequency self-pulsed mode produces a synthetic jet-like flow implying that a gas heating effect plays a role, even though the discharge current is small. The high-frequency self-pulsed mode produces pulsed jets in a tangent direction, and the continuous DC mode produces a steady straight pressure wave. Particle image velocimetry (PIV) images reveal that the induced flow field by the low-frequency self-pulsed mode has flow propagating in the radial direction and centered between the electrodes. The high-frequency self-pulsed mode and continuous DC mode produce flow from the anode to the cathode. The perturbed region downstream of the cathode is larger in the high-frequency self-pulsed mode with similar maximum speeds.

• The Korean Journal of Physiology
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• 제29권2호
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• pp.233-241
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• 1995

The nonapeptide bradykinin has been shown to exhibit an array of biological activities including relaxation/contraction of various smooth muscles. In order to investigate the effects of bradykinin on the contractility and the electrical activity of antral circular muscle of guinea-pig stomach, the isometric contraction and membrane potential were recorded. Also, using standard patch clamp technique, the $Ca^{2+}-activated$ K currents were recorded to observe the change in cytosolic $Ca^{2+}$ concentration. $0.4 {\mu}M$ bradykinin induced a triphasic contractile response (transient contraction-transient relaxation-sustained contraction) and this response was unaffected by pretreatment with neural blockers (tetrodotoxin, atropine and guanethidine) or with apamin. Bradykinin induced hyperpolarization of resting membrane potential and enhanced the amplitude of slow waves and spike potentials. The enhancement of spike potentials was blocked by neural blockers. Both the bradykinin-induced contractions and changes in membrane potential were reversed by the selective $B_2$-receptor antagonist $(N{\alpha}-adamantaneacetyl-_{D}-Arg-[Hyp, Thy,_{D}-Phe]-bradykinin)$. In whole-cell patch clamp experiment, we held the membrane potential at -20 mV and spontaneous and transient changes of Ca-activated K currents were recorded. Bradykinin induced a large transient outward current, consistent with a calcium-releasing action of bradykinin front the intracellular calcium pool, because such change was blocked by pretreatment with caffeine. Bradykinin-induced contraction was also blocked by pretreatment with caffeine. From these results, it is suggested that bradykinin induces a calciumrelease and contraction through the $B_{2}$ receptor of guinea-pig gastric smooth muscle. Enhancement of slow wave activity is an indirect action of bradykinin through enteric nerve cells embedded in muscle strip.

• 한국항해항만학회지
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• 제37권6호
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• pp.663-671
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• 2013

해운대 해수욕장은 육지로부터 유입되는 모래 공급원의 감소와 고파랑 및 반사파 등의 영향으로 백사장의 폭이 매년 감소하는 것으로 나타났다. 표사이동에 따른 해빈변형 문제를 해결하기 위해서는 해빈류의 특성을 예측할 필요가 있다. 본 연구에서는 해운대 해수욕장에 대한 장기적이고 종합적인 관측자료를 바탕으로, 계절별 대표파랑과 이상파에 대한 해빈류 및 표사이동 수치실험을 실시하였다. 여름에는 평상파 및 S계열 파랑에 의해서 해빈류는 연안을 따라 동쪽으로 흘러 미포측에서 퇴적되는 양상을 보이고, 겨울에는 평상파 및 E 계열의 파랑에 의해 해빈류는 서향하여 동백섬 인근에서 퇴적양상을 보이고 있다. 50년빈도 고파랑 내습시 SSW 파랑은 해운대 중앙에서 이안류가 발생하고, ESE 파랑은 미포측에서 연안을 따라 서측으로 흐름을 발생시키는 것으로 나타났다.

• Nuclear Engineering and Technology
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• 제40권3호
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• pp.213-224
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• 2008

The pumping of coolant in a liquid metal fast reactor may be performed with an annular linear induction electro-magnetic (EM) pump. Linear induction pumps use a traveling magnetic field wave created by poly-phase currents, and the induced currents and their associated magnetic field generate a Lorentz force, whose effect can be the pumping of the liquid metal. The flow behaviors in the pump are very complex, including a time-varying Lorentz force and pressure pulsation, because an induction EM pump has time-varying magnetic fields and the induced convective currents that originate from the flow of the liquid metal. These phenomena lead to an instability problem in the pump arising from the changes of the generated Lorentz forces along the pump's geometry. Therefore, a magneto-hydro-dynamics (MHD) analysis is required for the design and operation of a linear induction EM pump. We have developed a time-harmonic 2-dimensional axisymmetry MHD analysis method based on the Maxwell equations. This paper describes the analysis and numerical method for obtaining solutions for some MHD parameters in an induction EM pump. Experimental test results obtained from an induction EM pump of CLIP-150 at the STC "Sintez," D.V. Efremov Institute of Electro-physical Apparatus in St. Petersburg were used to validate the method. In addition, we investigated some characteristics of a linear induction EM pump, such as the effect of the convective current and the double supply frequency (DSF) pressure pulsation. This simple model overestimated the convective eddy current generated from the sodium flow in the pump channel; however, it had a similar tendency for the measured data of the pump performance through a comparison with the experimental data. Considering its simplicity, it could be a base model for designing an EM pump and for evaluating the MHD flow in an EM pump.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1407-1412
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• 2004

Impedance calculations of electric railway traction systems is essential to define characteristics and to design it. The self impedance is defined voltage drop rate per unit length, the mutual impedance is represented as a voltage induced to transmission line from transmission line. The self and the mutual impedance are influenced by ground return currents. The earth is considered as a semi-infinitely extended non-ideal conductor. The current of transmission line produces earth current induced magnetically and it flow through a path having minimum impedance. Carson proposed the impedance calculation formula using wave equations and magnetic field equations. Though the formula have an improper equation, that is still used as a standard impedance calculation method. This paper introduced an impedance calculation method that the complex depth of earth return method assumes that the current in conductor returns through an imagined earth depth path located directly under original conductor at a depth of. In this paper, we showed that this proposed method has a closed form and is easier than Carson's.