• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.196-199
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• 2004

This paper presents a structure of the searcher using the space diversity in array antenna system operating in the DS/CDMA signal environments. The new technique exploits the fact that the In-phase and Quadrature components of interferers can respectively be viewed as independent Gaussian noise at each antenna element in most practical CDMA (Code Division Multiple Access) signal environments. The proposed PN acquisition scheme is a single dwell serial PN acquisition system consisting of two stage, that is, the searching stage and the verification stage. The searching stage correlates the received signals with the local PN oscilator for obtaining the synchronous energy at the entire uncertainty region. The verification stage compares the searching energy with the optimal threshold, which is pre-designed in the Lock-Detector, and decides whether the acquisition is successful or fail. In this paper, we analyzed the relationship of both diversity order and the mean acquisition time. In general, It is known that the mean acquisition time decreases significantly as the number of antenna elements increases. But, the enhancement of the performance is saturated in terms of PN acquisition scheme. Therefore, to decrease the mean acquisition time, we must design the optimal array antenna system by considering the operating SNR range of the receiver, the detection probability, and the false alarm probability. The performance of the proposed acquisition scheme is analyzed in frequency-selective Rayleigh fading channels. In this paper, the effect of the number of antenna elements on acquisition scheme is considered in terms of the detection probability, false alarm probability. and the mean acquisition time.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.28.1-28.1
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• 2017

To investigate AGN outflows as a tracer of AGN feedback on the host galaxies, we perform integral-field spectroscopy of 20 type 2 AGNs at z<0.1 using the Magellan/IMACS and the VLT/VIMOS. The observed objects are luminous AGNs with the [O III] luminosity >$10^{41.5}erg/s$, and exhibit strong outflow signatures in the [O III] kinematics. We obtain the maps of the narrow and broad components of [O III] and $H{\alpha}$ lines by decomposing the emission-line profile. The broad components in both [O III] and $H{\alpha}$ represent the non-gravitational kinematics, (i.e., gas outflows), while the narrow components represent the gravitational kinematics (i.e., rotational disks), especially in $H{\alpha}$. By using the spatially integrated spectra within the flux-weighted size of the narrow-line region, we estimate the outflow energetics. The ionized gas mass is $(1.0-38.5){\times}10^5M_{\odot}$, and the mean mass outflow rate is $4.6{\pm}4.3M_{\odot}/yr$, which is a factor of ~260 higher than the mean mass accretion rate $0.02{\pm}0.01M_{\odot}/yr$. The mean energy injection rate is $0.8{\pm}0.6%$ of the AGN bolometric luminosity Lbol, while the mean momentum flux is $(5.4{\pm}3.6){\times}L_{bol}/c$, except for two most kinematically energetic AGNs. The estimated energetics are consistent with the expectations for energy-conserving outflows from AGNs, yet we do not find any supporting evidence of instantaneous star-formation quenching due to the outflows.

• Journal of the Korean Society of Clothing and Textiles
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• v.25 no.1
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• pp.83-90
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• 2001

Cooling garments are being considered for reducing heat strain in hot environment. We evaluated the effectiveness of ice gel-based cooling vest in hot environment both resting and exercising. Four male subjects were exposed to heat(4$0^{\circ}C$, 50%RH) with vest or without it. The results were as follows; In case of the trial wearing ice gel-based cooling vest, total body weight loss, and local sweat volume were less than those without it. Mean skin temperature, rectal temperature, pulse, energy expenditure, temperature of inside clothes, and humidity of inside also were lower than those without cooling vest. By subjective thermal sensation, subjective humidity sensation, and thermal comfort sensation, it was proved that non-wearing vest decreased comfort than wearing that. These results suggested that wearing ice gel-based cooling vest reduced human heat strain in hot environment both resting and exercising.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.1
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• pp.78-85
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• 1991

An experimental result for heat transfer of pulsating turbulent pipe flow was presented under the condition of fully developed dynamic regime and uniform wall heat flux. Experiments were performed at following conditions ; Inlet time-averaged Reynolds number varied from 5000 to 11000; The peak pressure fluctuation were 1.3, 2.3 and 3.5 percent of the mean pressure; Pulsating frequency ranged from 53 Hz to 320 Hz The measurements showed that the effect of pulsation on local heat transfer is greater at downstream, in which pulsating source exists, than upstream and the heat transfer rate, averaged over the pipe length, was higher or lower than in an equivalent non-pulsating flow according to the pulsating conditions. In addition, the significant change of heat transfer rate was observed in acoustically resonant conditions, when the pulsating frequency of the flow corresponded to the pipe natural frequency.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1441-1446
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• 2008

Seoul Metro Line 9 (SML9) is the first subway line that private capital invests in Korea. SML9 will cross Seoul, linking the Gimpo Airport to the Gangnam district (25.5km) opening in the first half of 2009. SML9 has a new model in Korea constructed by metropolitan government and private company and operated by specialized public transportation service provider. SML9 is confronted with tough environment of stagnated public transportation and strong competitor, Olympic city expressway. And SML9 is under pressure for showing high efficiency as non-governmental organization from both customers and government. Consequently SML9 must lead the maximum efficiency by using its material and human resource. It is necessary that SML9 raise a competitive power and display its ability in active collaboration with relative organization and company. Hereupon, I propose renovation plans from viewpoint of operation field of SML9, (1) efficient train scheduling regime focusing on the combination of express and local train (2) close connection of other mean of transportation and (3) effective connection convention with Airport Railroad (AREX) as the line connected directly.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2594-2600
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• 2020

A gamma camera system using radionuclide has a functional imaging technique and is frequently used in the field of nuclear medicine. In the gamma camera, it is extremely important to improve the image quality to ensure accurate detection of diseases. In this study, we designed a blind-deconvolution framework after a noise-reduction algorithm based on a non-local mean, which has been shown to outperform conventional methodologies with regard to the gamma camera system. For this purpose, we performed a simulation using the Monte Carlo method and conducted an experiment. The image performance was evaluated by visual assessment and according to the intensity profile, and a quantitative evaluation using a normalized noise-power spectrum was performed on the acquired image and the blind-deconvolution image after noise reduction. The result indicates an improvement in image performance for gamma camera images when our proposed algorithm is used.

• Wind and Structures
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• v.3 no.1
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• pp.11-21
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• 2000

This paper presents results of modeling of the passive contaminant diffusion from a continuous line finite-size source located on the underlying surface of a neutral near-ground atmospheric layer obtained by using the non-local two-parameteric turbulence model and the transport equation of mean concentration. In the proposed diffusion model the turbulent diffusion coefficient changes not only with the vertical coordinate but also with the distance downstream from the source according to the experimental data. The results of the modeling reproduce structural features of the concentration field.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.683-686
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• 2010

본 논문은 영상 내에서 영역을 분할하여 영상 잡음을 효과적으로 제거하는 기법을 제안한다. 제안한 방법을 통해 잡음 영상을 영역 분할 경우 잡음부분까지 영역 분할되는 문제가 발생하기 때문에 잡음 영상을 저대역(Low-pass) 필터를 통과함으로써 잡음을 최소화한다. 저대역 필터를 통과한 영상에서 에지를 추출하여 비정상적인 에지의 추출을 방지함으로써 영상이 가진 근본적인 에지를 정확하게 추출한다. 획득한 에지 정보를 바탕으로 각 영역간의 히스토그램의 평균 오차를 이용하여 영역을 분할한다. 분할된 영역은 각 영역별로 저대역(Low-pass) 필터를 통과시킴으로써 영역에 맞는 잡음 제거를 통해서 더욱 빠르고 효과적으로 제거한다. 본 논문의 방법은 기존의 학습을 통한 잡음 제거 방법과 다르게 학습 시간이 요구되지 않으며, Non-local Means의 방법과 다르게 큰 연산량을 요구하지 않기 때문에 유사한 성능으로 빠른 잡음 제거를 할 수 있다.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.33.1-33.1
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• 2018

The differential rotational properties of early-type galaxies (ETGs) revealed by integral field spectroscopy surveys is arguably one of the most exciting findings in the galaxy evolution study during the past decade. Numerical studies have shown that galaxy mergers under various configurations can reproduce the observed distribution of ETG spin. However, we suggest an alternative scenario for the spin evolution of a large fraction of ETGs. Using the Horizon-AGN simulation, we follow the spin evolution of 10037 color-selected ETGs more massive than 1010 Msun that are divided into four groups: cluster centrals (3%), cluster satellites (33%), group centrals(5%), and field ETGs (59%). We find a strong mass dependence of the slow rotator fraction, fSR, and the mean spin of massive ETGs. Although the environmental dependence is not clear in the fSR, it is visible in the mean value of the spin parameter. The environmental dependence is driven by the satellite ETGs whose spin gradually decreases as their environment becomes denser. Galaxy mergers appear to be the main cause of total spin changes in 94% of central ETGs of halos with Mvir > 1012.5 Msun, but only 22% of satellite and field ETGs. We find that non-merger induced tidal perturbations better correlate with the galaxy spin-down in satellite ETGs than mergers. Given that the majority of ETGs are not central in dense environments, we conclude that non-merger tidal perturbation effects played a key role in the spin evolution of ETGs observed in the local (z < 1) universe.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.6
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• pp.2853-2856
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• 2016

Background: Many studies have pointed to strategies to cope with patient anxiety in colposcopy. Evidence shows that patients experienced considerable distress with the large loop excision of transformation zone (LLETZ) procedure and suitable interventions should be introduced to reduce anxiety. This study aimed to investigate the effects of music therapy in patients undergoing LLETZ. Materials and Methods: A randomized controlled trial was conducted with patients undergoing LLETZ performed under local anesthesia in an out patient setting at Ramathibodi Hospital, Bangkok, Thailand, from February 2015 to January 2016. After informed consent and demographic data were obtained, we assessed the anxiety level using State Anxiety Inventory pre and post procedures. Music group patients listened to classical songs through headphones, while the control group received the standard care. Pain score was evaluated with a visual analog scale (VAS). Statistical analysis was conducted using Pearson Chi-square, Fisher's Exact test and T-Test and p-values less than 0.05 were considered statistically significant. Results: A total of 73 patients were enrolled and randomized, resulting in 36 women in the music group and 37 women in the non-music control group. The preoperative mean anxiety score was higher in the music group (46.8 VS 45.8 points). The postoperative mean anxiety scores in the music and the non-music groups were 38.7 and 41.3 points, respectively. VAS was lower in music group (2.55 VS 3.33). The percent change of anxiety was greater in the music group, although there was no significant difference between two groups. Conclusions: Music therapy did not significantly reduce anxiety in patients undergoing the LLETZ procedure. However, different interventions should be developed to ease the patients' apprehension during this procedure.