• Korean Journal of Mathematics
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• 제23권1호
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• pp.171-180
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• 2015

It is discovered in [7] that a dielectric material is coated by a plasmonic material of negative permittivity with dissipation, then cloaking by anomalous localized resonance may occur as the dissipation tends to zero. In this paper, we investigate numerically the pointwise behavior of the potential in the shell when cloaking by anomalous localized resonance (CALR) occurs. By changing locations a dipole source, we can observe some localizing properties of the potential in the shell.

• 대한수학회보
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• 제50권6호
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• pp.1765-1780
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• 2013

This paper deals with some types of semilinear parabolic systems with localized or nonlocal sources and nonlocal boundary conditions. The authors first derive some global existence and blow-up criteria. And then, for blow-up solutions, they study the global blow-up property as well as the precise blow-up rate estimates, which has been seldom studied until now.

• 대한전자공학회논문지TC
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• 제40권12호
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• pp.38-45
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• 2003

최근에 글로벌 QoS 라우팅방식의 약점을 개선하려는 노력으로 로컬 QoS 라우팅 방식이 제시되었다. 글로벌 라우팅과는 다르게 로컬 QoS 라우팅에서는 라우터간의 상태교환을 수행하지 않고 virtual capacity를 사용하여 라우터가 독자적으로 라우팅을 수행한다. 로컬 QoS 라우팅에서는 소스와 목적간의 경로가 효과적으로 선택되어야만 좋은 성능을 보장받을 수 있다. 본 논문에서는 효과적인 경로 선택을 위하여 몇몇의 휴리스틱을 제시하고 이를 활용한 경로 선택 알고리즘을 제안하였다. 제안된 알고리즘은 시뮬레이션과 함께 분석되었으며 경로선정방식에 따라 로컬 QoS 라우팅의 성능이 매우 큰 영향을 받는다는 것을 확인하였다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.279-284
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• 2007

The cultural noise sources in magnetotellurics were localized using the source localization method. Conventional beamforming techniques are not applicable for electromagnetic source localization. In this study, the matched field processing and genetic algorithm are used to localize an electromagnetic source and estimate the polarization direction. The source localization using MT field data shows the characteristics of estimated source distribution related to the strength of cultural noise.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.184-184
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• 2012

Recently, InGaN/GaN multi-quantum well grown on GaN pyramid structures have attracted much attention due to their hybrid characteristics of quantum well, quantum wire, and quantum dot. This gives us broad band emission which will be useful for phosphor-free white light emitting diode. On the other hand, by using quantum dot emission on top of the pyramid, site selective single photon source could be realized. However, these structures still have several limitations for the single photon source. For instance, the quantum efficiency of quantum dot emission should be improved further. As detection systems have limited numerical aperture, collection efficiency is also important issue. It has been known that micro-cavities can be utilized to modify the radiative decay rate and to control the radiation pattern of quantum dot. Researchers have also been interested in nano-cavities using localized surface plasmon. Although the plasmonic cavities have small quality factor due to high loss of metal, it could have small mode volume because plasmonic wavelength is much smaller than the wavelength in the dielectric cavities. In this work, we used localized surface plasmon to improve efficiency of InGaN qunatum dot as a single photon emitter. We could easily get the localized surface plasmon mode after deposit the metal thin film because lnGaN/GaN multi quantum well has the pyramidal geometry. With numerical simulation (i.e., Finite Difference Time Domain method), we observed highly enhanced decay rate and modified radiation pattern. To confirm these localized surface plasmon effect experimentally, we deposited metal thin films on InGaN/GaN pyramid structures using e-beam deposition. Then, photoluminescence and time-resolved photoluminescence were carried out to measure the improvement of radiative decay rate (Purcell factor). By carrying out cathodoluminescence (CL) experiments, spatial-resolved CL images could also be obtained. As we mentioned before, collection efficiency is also important issue to make an efficient single photon emitter. To confirm the radiation pattern of quantum dot, Fourier optics system was used to capture the angular property of emission. We believe that highly focused localized surface plasmon around site-selective InGaN quantum dot could be a feasible single photon emitter.

• The Journal of the Acoustical Society of Korea
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• 제20권1E호
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• pp.31-37
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• 2001

Matched Field Processing (MFP) is a successive process of correcting mismatches between true and assumed parameters by matching the measured acoustic field data with numerically simulated data which we call replica. The MFP is widely used both in geo-acoustic parameter inversions and in source localizations. Whether a certain parameter can be inverted effectively or whether a source can be localized correctly depends on the amount of the influence that a parameter has on the acoustic field during the matching process. Sensitive parameters can be better estimated than the less sensitive ones in MFP. On the contrary, the sensitive parameters affect adversely on the source localization results when they have uncertainties. In this paper, a sensitivity index is defined based upon the field variation resulting from the perturbed parameters. Numerical test results show that the index behaves in accordance with the results of source localization under a mismatched environment and also with the inversion solutions.

• 대한의용생체공학회:의공학회지
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• 제25권6호
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• pp.575-580
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• 2004

본 연구에서는 뇌자도 신호의 전체 평균을 구하고 표준뇌를 이용하여 전류원의 해부학적 위치를 대략적으로 추정하는 방법을 제시하였다. Minimum norm estimation 알고리듬과 truncated singular value decomposition을 이용하여 측정된 신호를 재현할 수 있는 전류원 분포를 구하고, 이 전류원에 의해 표준 센서면에서 측정될 것으로 예상되는 신호로 변환한 다음 모든 피실험자에 대한 전체 평균을 구하였다. 모의 실험에서는 서로 다른 위치에서 측정된 피실험자의 뇌자도 신호의 전체 평균에서 얻은 전류원이 각 피실험자의 뇌자도 신호에서 얻은 전류원의 평균값과 수 mm 이내에서 일치하였다. 이는 신호가 미약하더라도 활동 부위의 평균적인 위치를 전체 평균에서 알 수 있음을 보여주며 청각 자극에 대한 N100m 신호의 전류원을 구하여 실험적으로 확인하였다. 또한 이 결과는 전체 평균에서 구한 활동부위의 전류원 정보를 N100m의 전류원을 기준점으로 표준뇌에 대략적으로 표시할 수 있음을 보여준다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.846-853
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• 2005

The whole death by disaster is totalized to 1,515 person from 1993 to 2004 year in our country. In this section life damages by landslide is totalized 357 people(about 24% of whole life damage). About 36 people are died by landslide(such as cutting area failure every year). Kangwon-do need a lot of interests and prevention because dangerous area that landslide occurrence is more than other area at summer localized downpour or thawing season and there is landslide occurrence possibility area more than other area. Kangwon-do area is higher than other area in natural disaster incidence and damage scale because topography and a lot of rainfalls by summer localized in Kangwon-Do than other area. In this study, dangerous area of landslide occurrence possibility is analyzed and compared Kangwon-Do with other areas in our country. as a result, every year we have experienced landslide occurrence and natural disaster. accordingly, we urgently need to prevent landslide occurrence and natural disaster by analy-zed source about landslide occurrence and condition of disaster in Kangwon-Do and suitable engineering method and construction work.

• Journal of Welding and Joining
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• 제25권3호
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• pp.78-84
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• 2007

Laser Material Processing has been replaced the conventional machining systems - cutting, drilling, welding and surface modification and so on. Especially, LTH(Laser Transformation Hardening) process is one branch of the laser surface modification process. Conventionally, some techniques like a gas carburizing and nitriding as well as induction and torch heating have been used to harden the carbon steels. But these methods not only request post-machining resulted from a deformation but also have complex processing procedures. Besides, LTH process has some merits as : 1. It is easy to control the case depth because of output(laser power) adjustability. 2. It is able to harden the localized and complicated a.ea and minimize a deformation due to a unique property of a localized heat source. 3. An additional cooling medium is not required due to self quenching. 4. A prominent hardening results can be obtained. This study is related to the surface hardening of the rod-shaped carbon steel applied to the lathe based complex processing mechanism, a basic behavior of surface hardening, hardness distribution and structural characteristics in the hardened zone.

• 지구물리와물리탐사
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• 제7권1호
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• pp.51-55
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• 2004

This paper presents a fast and stable imaging scheme using the localized nonlinear (LN) approximation of integral equation (IE) solutions for inverting electromagnetic data obtained in a crosswell survey. The medium is assumed to be cylindrically symmetric about a source borehole, and to maintain the symmetry a vertical magnetic dipole is used as a source. To find an optimum balance between data fitting and smoothness constraint, we introduce an automatic selection scheme for a Lagrange multiplier, which is sought at each iteration with a least misfit criterion. In this selection scheme, the IE algorithm is quite attractive for saving computing time because Green's functions, whose calculation is a most time-consuming part in IE methods, are repeatedly re-usable throughout the inversion process. The inversion scheme using the LN approximation has been tested to show its stability and efficiency, using both synthetic and field data. The inverted image derived from the field data, collected in a pilot experiment of water-flood monitoring in an oil field, is successfully compared with that derived by a 2.5-dimensional inversion scheme.