• KIEAE Journal
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• v.11 no.6
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• pp.53-62
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• 2011

This study aimed at suggesting improvement of lighting environment of the coffee house using study place. To this end, a series of field investigation was conducted in four possible target coffee houses around university. The field measurement included measurement of general illuminance and tabletop illuminance, observing illumination condition, and status of artificial lighting. Also, on-site questionnaire survey was administrated to 80 users of field measurement targets about using characteristics of coffee house and user's subjective response on light environment. The results are summarized as follows: (1) According to questionnaire survey, most of users checked 'learning (study and reading)' in 'purpose of coffee house using', and 'slightly dark' was checked most in each subjective response (brightness on general space and on tabletop at daytime/night); (2) as results of measurements on general illuminance and on tabletop illuminance during daytime, only one coffee house was suitable for standard; (3) as results of measurements on illuminance during night, all target coffee houses were not met the standard; (4) as results of uniformity ratios, almost uniformities of general illuminance were not met the standard except one case. The common problems of lighting environment of coffee house were analyzed as lack of daylight illumination e.g. having low amount of sunshine from skylight, un-uniformity of insolation by floor plan and absence of window blind, and un-uniformity of artificial luminous intensity e.g. lack of the number or brightness of artificial lighting, using the indirect lighting, using only local lighting, and non-uniform arrangement of artificial lighting.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.4
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• pp.49-55
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• 2010

In this paper, we propose the symbol decision method considering the non-uniformity in color space and analyze the BER performance of modulation scheme based on color space, comparing with the conventional WDM scheme based on light intensity. Through numerical simulation, we show the BER performance superiority under the condition of AWGN and common mode noise.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.12
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• pp.547-549
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• 2006

We have proposed a novel algorithm for detecting scan alluk on the surface of a TFT-LCD device that is generated by non-uniform exposure during fabrication. The scan alluk is known to have similar intensity values on paths that are determined by the shape of lens for light exposure. Based on the observation, the proposed algorithm inspects the uniformity on the paths using 1D projection image of 2D LCD image and 2D backprojection image of the 1D image. We have shown the usefullness of the proposed method by theoretical analysis and experimental results.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.48-52
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• 2005

The research topic of super-RENS technology is shifting from the signal intensity (CNR; Carrier to Noise Ratio) to the signal uniformity (Jitter or bER). To achieve an uniform signal characteristics, it is important to reduce signal fluctuation in a super-RENS disc. In this study, we investigated the relation between signal fluctuation and low frequency noise (LFN), and analyzed LFN increase in recording and readout processes. It was found that signal fluctuation had a close relationship with the LFN. Also, it was found that the recorded mark shape such a bubble type and high readout power increased the LFN in recording and readout process of a super-RENS disc. So, using non-bubble type recording material and low super-resolution readout material, we markedly improved the LFN in a super-RENS disc.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.98-98
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• 2002

목적： RF Coil sensitivity 또는 MRI system의 여러 요인들로 인해서 생길 수 있는 영상의 Bias field 즉, 유난히 밝거나 어두운 부분을 raw data 의 low frequency 값들을 임의로 변화를 줌으로써 어느 정도 보정이 가능하다. 대상 및 방법： Bias field로 인해서 분석에 어려움이 있는 이미지의 k-space 데이터를 가지고 있으면 부위에 상관없이 모두 가능하다. k-space에서 얻어진 raw data를 Kx와 Ky의 2-D로 표현한 후에 DC 성분에 해당하는 영점을 그대로 놔둔 상태에서 영점 주변으로 일정 범위 안에 있는 low frequency 성분 값들을 FT(Fourier Transform)를 거치기 전에 0으로 바꾼 후에 image processing을 거치도록 한다.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.81.1-81.1
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• 2019

Linear sausage oscillations of a cylinder embedded in a plasma with an azimuthal magnetic field, created by a current on the surface of the cylinder, are studied. Such a plasma configuration could be applied to modelling demonstrate that the lowest radial harmonic of the sausage mode is in the trapped regime for all values of the parallel wave number. In the long-wavelength limit, phase and group speeds of this mode are equal to the Alfven speed in the external medium. It makes the oscillation period to be determined by the ratio of the parallel wavelength, e.g., double the length of an oscillating loop, to the external Alfven speed, allowing for its seismological estimations. The application of the results obtained to the interpretation of long-period (longer than 20-30 s) oscillations of emission intensity detected in solar coronal structure, gives reasonable estimations of the external Alfven speed. Cutoff values of the parallel wavenumber for higher radial harmonics are determined analytically. Implications of this finding to the observational signatures of fast magnetoacoustic wave trains guided by the plasma non-uniformity are discussed.

• Journal of the Korean Society of Visualization
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• v.9 no.1
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• pp.36-41
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• 2011

It is highly needed to measure the dissolved oxygen (DO) concentration field in water for a variety of purposes such as biological, industrial, environmental monitoring and medical application. Application of PSP (Pressure Sensitive Paint) which is sensitive to oxygen concentration has been carried out to measure DO concentration field using PtOEP/PS film and intensity based method under the UV-LEDs illumination. A micro round water jet having 100% of DO was obliquely impinged on to a PtOEP/PS film coated plate placed in a 0% of DO water container. DO concentration fields on the impinging plate were quantitatively visualized with a $2.94\;{\mu}m$ of spatial resolution. Through pixel-by-pixel calibration, uncertainty of each pixel by different sensitivity, different dye concentration and non-uniformity of illumination was removed. It is demonstrated that the high DO concentration region was coincided with the impingement area. The DO concentration gradient due to DO diffusion was affected by Reynolds number.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.1
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• pp.18-30
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• 1993

A numerical analysis has been carried out on the Czochralski flow fields when uniform and nonuniform magnetic fields are applied. Czochralski flow fields are governed by buoyancy forces, thermocapillarity, centrifugal forces, and applied magneic fields. In this analysis, pressure and three components of velocity vectors are obtained, and circumferential electrical currents are calculated. When a uniform magnetic field is applied, all the velocity components are decreased and the circumferential electric currents near the crystal surface are increased as the magnetic field intensity is increased. In the case of a nonuniform field, the flows in a meridional plane are suppressed and the circumferential velocity is increased as the non uniformity is increased. The understanding on the Czochralski flow fields under the influence of magnetic fields can lead to the study on the behavior of the concentration of the solute and impurities.

• Korean Journal of Remote Sensing
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• v.25 no.3
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• pp.295-309
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• 2009

In this study, an iterative maximum a posteriori (MAP) approach using a Bayesian model of Markovrandom field (MRF) was proposed for despeckling images that contains speckle. Image process is assumed to combine the random fields associated with the observed intensity process and the image texture process respectively. The objective measure for determining the optimal restoration of this "double compound stochastic" image process is based on Bayes' theorem, and the MAP estimation employs the Point-Jacobian iteration to obtain the optimal solution. In the proposed algorithm, MRF is used to quantify the spatial interaction probabilistically, that is, to provide a type of prior information on the image texture and the neighbor window of any size is defined for contextual information on a local region. However, the window of a certain size would result in using wrong information for the estimation from adjacent regions with different characteristics at the pixels close to or on boundary. To overcome this problem, the new method is designed to use less information from more distant neighbors as the pixel is closer to boundary. It can reduce the possibility to involve the pixel values of adjacent region with different characteristics. The proximity to boundary is estimated using a non-uniformity measurement based on standard deviation of local region. The new scheme has been extensively evaluated using simulation data, and the experimental results show a considerable improvement in despeckling the images that contain speckle.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.87-87
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• 2018

This study was conducted to investigate the effects of osmotic priming, liquid smoke (LS), sonication and modified drum priming treatments to improve the germination speed and uniformity of pepper seeds for high quality export seeds. Seeds were treated in 0.5, 1.0, 5.0, 10% LS solution only or with 100mM $K_2SO_4$ solution for 6days at $15^{\circ}C$. Sonication treatment was performed for 5, 10, and 20 minutes at an intensity of 5.2, 10.4, 15.7, 21.0, 26.1kHz in water at $15^{\circ}C$. After sonication treatment, seeds were primed with water or 100mM $K_2SO_4$ for 4days. 40, 50 and 60% seed moisture content (SMC) of hydrated seeds were incubated for 84, 96 and 108h in a container with a relative humidity of 99% at 26rpm for a modified drum priming treatments. 0.5% LS treatment with water or 100mM $K_2SO_4$ priming showed significant effects with 71% GP (9.0days MGT) and 66% GP (7.4days MGT), respective, while untreated seeds resulted in only 61% GP and 10days MGT. The healthy seed % was increased by 24% by $K_2SO_4$ priming with LS treatment compared to untreated seeds. However, sonication treatment showed less germination or no difference compared to untreated seed, regardless of intensity and treatment time. The modified drum priming treatment (108h incubation after 50% SMC hydration) significantly improved the GP (on the $4^{th}$days after sowing), germination rate (GR), and MGT to 65%, $28%{\cdot}day^{-1}$, and 3.6days, whereas untreated seed resulted only 7% GP, $17%{\cdot}day^{-1}$ GR and 5.9days MGT. Thus, modified drum priming treatment effectively improved seed germination and is considered as an industrially promising treatment methods considering the shortening of the treatment period and environment-friendly aspects.