• 한국전기전자재료학회논문지
• /
• 제17권6호
• /
• pp.622-632
• /
• 2004

We have studied how liquid crystal's rubbing direction and voltage driving method affect generation of disclination line. At first, generation of disclination line in vertical alignment(VA) cell and VA-twisted nematic(TN) cell has been examined. When liquid crystal's rubbing direction of bottom substrate was 0$^{\circ}$, the degree of generated disclination line was the smallest value. Further, the generation of disclination line above the electrode is less in the frame inversion than in the line inversion. Secondly, we have examined a generation of disclination line in reflective fringe-field switching cell. When the distance between common electrodes is over 3 ${\mu}{\textrm}{m}$ with on-state of one pixel and off-state of neighboring pixels, the reflectance appears only on-state pixel without generating reflectance in adjacent pixels.

• 천문학논총
• /
• 제8권1호
• /
• pp.83-104
• /
• 1993

In principle, both radiation and collision are capable of pumping the SiO masers. In order to check which pumping mechanism is more efficient, we calculated the rate equation for our model including the 3 vibrational slates with 7 rotational states of each vibrational slate. Through solving the radiative transfer equation with the Sovolev approximation, we estimated the line profiles from an expanding envelope for several transitions. It is found that the collision works more efficiently than the radiation for the inversion in excited vibrational stales. However in an expanding envelope model we could not get the strong line intensity as observed one because the population inversion is possible only in a small restricted region. For the enough population inversion to get type observed maser intensity. the number density of SiO and hydrogen molecules should be up to about $2{\times}10^5\;cm^{-3}$ and $1{\times}10^9\;cm^{-3}$, respectively, and the inversion should be occured in the region of no Jess than 11014cm.

• 천문학회보
• /
• 제46권2호
• /
• pp.46.3-47
• /
• 2021

Recently a multilayer spectral inversion (MLSI) model has been proposed to infer the physical parameters of plasmas in the solar chromosphere. The inversion solves a three-layer radiative transfer model using the strong absorption line profiles, H alpha and Ca II 8542 Å, taken by the Fast Imaging Solar Spectrograph (FISS). The model successfully provides the physical plasma parameters, such as source functions, Doppler velocities, and Doppler widths in the layers of the photosphere to the chromosphere. However, it is quite expensive to apply the MLSI to a huge number of line profiles. For example, the calculating time is an hour to several hours depending on the size of the scan raster. We apply deep neural network (DNN) to the inversion code to reduce the cost of calculating the physical parameters. We train the models using pairs of absorption line profiles from FISS and their 13 physical parameters (source functions, Doppler velocities, Doppler widths in the chromosphere, and the pre-determined parameters for the photosphere) calculated from the spectral inversion code for 49 scan rasters (~2,000,000 dataset) including quiet and active regions. We use fully connected dense layers for training the model. In addition, we utilize a skip connection to avoid a problem of vanishing gradients. We evaluate the model by comparing the pairs of absorption line profiles and their inverted physical parameters from other quiet and active regions. Our result shows that the deep learning model successfully reproduces physical parameter maps of a scan raster observation per second within 15% of mean absolute percentage error and the mean squared error of 0.3 to 0.003 depending on the parameters. Taking this advantage of high performance of the deep learning model, we plan to provide the physical parameter maps from the FISS observations to understand the chromospheric plasma conditions in various solar features.

• 대한기계학회논문집B
• /
• 제24권4호
• /
• pp.533-542
• /
• 2000

Analytical experiments to determine the line-of-sight temperature distribution is conducted by using spectral radiation intensities. For this study, fourteen narrow bands of $25cm^{-1}$ interval in $CO_2\;4.3{\mu}m$ band ($2,050cm^{-1}$ to $2375cm^{-1}$) are selected. The applied system is a one-dimensional gas slab filled with 100% $CO_2$ gas at 1 atm. Two types of temperature profile are tested; parabolic and boundary layer types. Three kinds of radiation calculation are used in the iteration procedure for the temperature inversion; LBL(Line by Line), SNB(Statistical Narrow Band) and WNB(WSGGM. based Narrow Band) models. The LBL solution shows perfect agreement while some error of temperature prediction is caused by radiation modeling error when using SNB and WNB models. The inversion result shows that the WNB model may be used more accurately in spectral remote sensing techniques than the traditional SNB model.

• 대한전자공학회논문지TC
• /
• 제38권8호
• /
• pp.1-10
• /
• 2001

본 논문에서는 전송 분야 뿐만 아니라 interconnection 분야에서 사용할 수 있는 새로운 선로 부호를 제안한다. 제안된 선로 부호는 1 비트의 잉여(redundancy) 비트를 사용하면서도 선로 부호가 갖는 기본적인 특징을 보장하며, interconnection 분야에서 필요한 byte 또는 frame 동기를 위한 직렬 동기 패턴 제공, 특수 문자 또는 in-band signaling을 제공한다. 8비트 이상의 병렬 데이터를 부호화 하거나 직렬 비트 스트림(steam)으로 전송하기 쉽게 하여 주는 제안된 NIBI 부호 생성 알고리즘, 복호 알고리즘 및 부호 성능에 대해서 기술한다.

• 지구물리
• /
• 제2권2호
• /
• pp.135-142
• /
• 1999

선형 자기쌍극자 모델의 하나인 철근에 대하여 3성분 자력계를 이용한 자력검층을 실시한 후 검층자료를 최소 자승법에 의한 역산을 이용하여 해석하였다. 본 실험에 사용된 철근의 길이는 1.12 m, 샘플링 간격은 0.05 m, 자력계와 철근사이의 거리는 0.3 m이며, 철근의 상단부를 깊이 0 m 지점에 고정하였다. 철근은 연직에 가깝도록 위치시켰다. FFT를 이용하여 평활화한 자기이상을 역산의 입력자료로 활용하였다. 검층자료의 해석을 위하여 선형 자기쌍극자의 상단부 심도, 길이, 단위 길이 당 자기모멘트, 자화방향(편각 및 복각), 경사방향과 경사각 등을 미지수로 설정하였다. 자기이상의 수평성분 및 수직성분 각각에 대한 역산 결과와 수평성분과 수직성분을 동시에 고려한 역산 결과를 비교하였는데 각각의 역산결과는 다소 차이를 보인다. 자기이상의 수평성분과 수직성분을 동시에 고려하여 역산을 수행하는 것이 각각의 성분을 역산하는 경우보다 정확한 해석이 가능한 것으로 판단된다. 이 때 철근 하단부의 추정 심도는 1.18 m로, 실제 심도인 1.12 m에 매우 근접하며, 철근의 복각은 -76°로 추정되었다. 철근의 복각이 음(-)의 값을 갖는 것은 철근의 유도자화 강도에 비하여 잔류자화 강도가 훨씬 커서, 전체적인 자화 방향이 철근의 상단 방향을 향하고 있기 때문으로 해석된다.

• 천문학회보
• /
• 제36권2호
• /
• pp.95.2-95.2
• /
• 2011

The most powerful technique for deducing the magnetic structure of the Sun is spectro-polarimetry. Detailed measurements of the polarization signal of the spectral lines (Stokes vector) allow us to infer the physical conditions in the solar atmosphere prevailing during the line formation. Inversion codes are the main tool to extract this information from the Stokes spectra. This study will focus on measurements of the chromospheric He I 1083.0 nm triplet and the photospheric Si I 1082.7 nm line. A spectropolarimetric data set of sunspots, obtained with the German Vacuum Tower Telescope (VTT) at the Teide observatory on Tenerife, is analyzed using an inversion technique. We will introduce the German Vacuum Tower Telescope and the inversion code HeLix, and will show data sets that are analyzed by HeLix.

• 천문학회보
• /
• 제46권2호
• /
• pp.77.3-78
• /
• 2021

Measuring radiative loss from the solar chromospheric lines like Ha line, Ca II 8542 line helps to infer the exact amount of non-thermal heating in the solar atmosphere. By courtesy of the multi-layer spectral inversion, it is able to determine the radiative loss in the upper and lower chromosphere. Consequently, we found that the radiative loss is around 10 kW/m², which is consistent with previous studies. Comparing the radiative loss at the upper and lower chromosphere, the loss at the lower chromosphere is larger than that of upper chromosphere and tends to spread all over the field of view while the loss in the upper chromosphere tends to be localized. We hope to find a hint for specific non-thermal heating process to explain the chromospheric radiative loss.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2000년도 가을 학술발표회 논문집
• /
• pp.231-236
• /
• 2000

In order to predict depth of the pile forward modeling and inversion of magnetic logging data was conducted by using a finite line of dipoles model. The horizontal component as well as the vertical component of magnetic fields can be measured in the borehole, and the magnetic anomalies can be obtained by subtracting the Earth's magnetic field from the measurement. The magnetic anomalies of the pile are considered as vector sum of induced magnetization due to the Earth's magnetic field and remnant magnetization possessed by steel strings in the pile. The magnetic anomalies are used as input data for inversion from which the length, the magnetic moment per unit length, and the dip angle of the pile can be obtained. From the inversion of synthetic noisy data, and the data obtained from the field model test it is found that the driving depth of the pile can be determined as close to the order of measuring interval (5∼10㎝). It is also found that the resultant magnetic anomalies due to an individual steel string in the pile are almost same as those due to a group of steel strings located at the center of the pile. The magnetic logging method also can be used for locating reinforced bars, pipes, and steel casings.

• 지구물리와물리탐사
• /
• 제22권3호
• /
• pp.160-167
• /
• 2019

저수지 제체는 3차원 전기비저항 구조로 구성되어 있기 때문에, 전기비저항 격자구조에 담수호의 수위변화에 따른 제체 내부의 침윤선 변동과 함께 담수호의 전기전도도가 고려되지 않는 경우 전기비저항 역산 결과가 왜곡될 수 있다. 이 연구에서는 3차원 전기비저항 탐사 모델링을 통하여, 저수지의 3차원 비저항 구조와 저수지 수위의 변화에 따른 제체 내부의 비저항 변화를 해석하였다. 이 분석 결과에 근거하여 국내 283개소 저수지를 대상으로 3차원 모델링에 의한 2차원 이론자료와 현장 2차원 탐사자료에 대한 역산 결과를 비교하였다. 마지막으로 두 역산의 비가 50% 이상이 되는 저수지를 추가 정밀조사 대상 저수지로 선정하였다.