• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.6
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• pp.20-26
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• 2008

Today, there are many high speed data access systems that provide the truly "anytime and anywhere" services. Especially, HSDPA (High Speed Data Packet Access), one of the main third generation mobile communication systems, provides 14.4Mbps maximum data throughput. However, HSDPA will fail to provide high data throughput in hostile multipath fading environments due to lack of LOS (Line of Sight). HAPS (High Altitude Platform Station) is one of the solutions to this problem. HAPS system not only provides Los, but it can also provide high data rate services to the conventional terrestrial systems. This paper proposes HAPS-HSDPA system model and compares performance of HSDPA and HAPS-HSDPA.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.119-120
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• 2015

We report results of the measurement of the trigonometric parallax of an $H_2O$ maser source in IRAS 22555+6213 with the VLBI Exploration of Radio Astrometry (VERA). The annual parallax was determined to be $0.278{\pm}0.019$ mas, corresponding to a distance of $3.66^{+0.30}_{-0.26}kpc$. Our results confirm that IRAS 22555+6213 is located in the Perseus arm. We computed the peculiar motion of IRAS 22555+6213 to be ($U_{src}$, $V_{src}$, $W_{src}$) = ($0{\pm}1$, $-32{\pm}1$, $9{\pm}1$) $km\;s^{-1}$, where $U_{src}$, $V_{src}$, and $W_{src}$ are directed toward the Galactic center, in the direction of Galactic rotation and toward the Galactic north pole, respectively. IRAS 22555+6213, NGC7538 and Cepheus A lie along the same line of sight, and are within $2^{\circ}$ on the sky. Their parallax distances, with which we derived their absolute position in the Milky Way, show that IRAS 22555+6213 and NGC7538 are associated with the Perseus arm, while Cepheus A is located in the Local arm. We compared the kinematic distances of IRAS 22555+6213 derived with flat and non-flat rotation curve with its parallax distance and found the kinematic distance derived from the non-flat rotation assumption ($-32km\;s^{-1}$ lag) to be consistent with the parallax distance.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.397-399
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• 2015

Recently, cosmic voids have been recognized as a powerful cosmological probe. A number of studies have focused on the effects of the gravitational lensing by voids on the temperature (and in some cases polarization) anisotropy of the Cosmic Microwave Background (CMB) background at relatively large to medium scales, l ~ 1000. Many of these studies attempt to explain the unusually large cold spot in CMB temperature maps and dynamical evidence of dark energy via detections of late-time integrated Sachs Wolfe (ISW) effect. Here, the effects of lensing by voids on the CMB temperature anisotropy at small scales, up to l = 3000, will be investigated. This work is carried out in the light of the benefits of adding large catalogues of cosmic voids, to be identified by future large galaxy surveys such as EUCLID and LSST, to the analysis of CMB data such as those from Planck mission. Our numerical simulation utilizes two methods, namely, the small-de ectionangle approximation and full ray-tracing analysis. Using the fitted void density profiles and radius (RV ) distribution available in the literature from N-body simulations, we simulated the secondary temperature anisotropy (lensing) of CMB photons induced by voids along a line of sight from redshift 0 to 2. Each line of sight contains approximately 1000 voids of effective radius $RV_{,eff}=35h^{-1}Mpc$ with randomly distributed radial and projected positions. Both methods are used to generate temperature maps. The two methods will be compared for their accuracy and effciency in the implementation of theoretical modeling.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1135-1139
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• 2017

Spatial distribution of chemical species in flame is a important indicator understanding the flame structure and combustion characteristics, and optical emission spectroscopy has been widely used for the measurement because of its simple and non-intrusive methodology. In this study, we suggest the feasibility of the measurement of chemical species (OH radical) distribution in rocket plume using optical emission spectrometer which was developed for the spatially resolved measurement along the line-of-sight. In order to predict the ground state concentration of species from the measured emission intensity by optical emission spectrometer, we consider thermal and chemical excitation mechanisms in flame, and assume thermodynamic equilibrium for the thermally excited species. We also present the spatial resolution and the correction of collection characteristics of the optical emission spectrometer depending on object distance.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.5
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• pp.491-496
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• 2013

Since IMO(International Maritime Organization, hereafter IMO) has decided the Wing-In-Ground craft as one of the ships, A few regulations and recommendations have been revised and approved internationally and domestically. However, the navigation rules considering types and navigation characteristics to secure the safe navigation of Wing-In-Ground craft are not sufficient and especially, there are no navigation rule between Wing-In-Ground crafts. In this situation, it is judged that the navigation rules related to the Wing-In-Ground crafts in any condition of visibility should be moved to the section of the ones in sight of one another to define the responsibilities between WIG and other vessels, and the new regulation, which Type 'B' and 'C' WIGs should avoid Type 'A' WIG, has to be established to ensure the safe navigation between WIGs on the current laws.

• Journal of the Korean Society of Food Culture
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• v.28 no.6
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• pp.585-593
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• 2013

This study was designed to measure taste sensitivity and the five basic senses by an educational classification instrument. The instrument was a rice kit that could use samples in a dry powder form or oil extract after long-term storage To test for taste, sucrose, salt, citric acid, and quinine sulfate were made at different concentrations and taste sensitivity was measured on a scale from level 1 to level 5. To obtain baseline data, an inspection tool for the five senses was used and randomly applied on 101 schoolchildren in the third and fourth grade in the city of Cheonan in Korea. The inspection tool was composed of 17 questions; 5 questions regarding visual characteristics and three questions each for characteristics regarding taste, hearing, smell, and touch. The average age of the schoolchildren was 9.5 years old and there were 49 third grade students (9 years of age), and 52 fourth grade students (ten years of age). There were slightly more male students than female students, 56 (55.4%) compared to 45 (44.6%), respectively. The average height of female students was higher than that of males, but the average BMI (body mass index) of the male students was slightly higher than that of female students (18.28 compared to 18.09, respectively). Female students were slightly more sensitive to salty tastes than male students (2.8 compared to 2.5, respectively). In the score distribution for each sense, touch sense was the highest at 7.59, sight sense was 7.49, hearing sense was 5.43, smell sense was 5.24, and taste sense was lowest at 3.69. Therefore, schoolchildren first tend to recognize and deem important the touch and sight of food before its taste.

• Journal of Hydrogen and New Energy
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• v.27 no.3
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• pp.318-327
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• 2016

In order to improve the performance of temperature field measurements by CT-TDLAS (Computer Tomography Tunable Diode Laser Absorption Spectroscopy), a new reconstruction algorithm, named two-ratios-of-three-peaks method is proposed in this paper. Further, two methods for selecting appropriate initial values of the iterative calculation of CT-TDLAS are proposed. One is MLOS (multiplicative line of sight) method and the other one is ALOS (additive line of sight) method. Two-ratios-of-three-peaks (2R3P) algorithm combined with MART (multiplicative algebraic reconstruction technique) is finally developed for the enhancements of reconstructive calculations. The results have been compared with those obtained by the conventional one-ratio-of-two-peaks (1R2P) algorithm. In order to evaluate the performance of this algorithm, numerical test has been performed using phantom Gaussian temperature distributions with $11{\times}11$ square mesh. The performance of the constructed algorithm has been demonstrated by comparing the results obtained in actual burner experiments with those obtained by thermocouples. It has been verified that 2R3P algorithm with MART and MLOS showed best performance than that of 1R2P algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.11 s.114
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• pp.1058-1064
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• 2006

In this paper, the channel capacity of a specified wireless indoor multiple-input multiple-output(MIMO) channel is estimated by analyzing spatial characteristics of this channel using the three-dimensional ray tracing method, and a technique for deriving an optimized separation of multi-antenna elements is proposed. At first, the ray paths, the path losses, and the time-delay profile are computed using the three-dimensional ray tracing method in an indoor corridor environment, which has the line of sight(LOS) and non-line of sight(NLOS) regions. The ray tracing method is verified by a comparison between the computation results and the measurements which are obtained with dipole antennas, an amplifier and a network analyzer. Then, an MIMO system is positioned in the indoor channel environment and the ray paths and path losses are computed for four antenna-position combinations and various values of the antenna separation to obtain the channel capacity for the MIMO system. An optimum antenna-separation is derived by averaging the channel capacities of 100 receiver positions with four different antenna combinations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.6
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• pp.628-636
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• 2014

This paper describes the design and analysis of five-element planar array antenna of an anti-jamming satellite navigation system. We propose a design of multi-layer patch antenna for Global Positioning System(GPS) $L_1/L_2$ dual bands. The proposed antenna has two ports feeding network with a hybrid chip coupler for a broad bandwidth with Right-Handed Circular Polarization(RHCP). The measurement results show the bore-sight gains of 1.10 dBic($L_1$) and 0.37 dBic($L_2$) for the center element. The bore-sight gains of an edge element are 0.99 dBic($L_1$) and -0.57 dBic($L_2$). At a fixed elevation angle of $30^{\circ}$, antennas show average gains of -2.08 dBic ($L_1$) and -5.33 dBic($L_2$) for the center element, and average gains of -0.40 dBic($L_1$) and -2.09 dBic($L_2$) for the edge elements. The results demonstrate that the proposed array antenna is suitable for anti-jamming applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.3
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• pp.230-239
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• 2009

In this paper, we propose a novel on-glass antenna for FM radio reception in a recreation vehicle(RV). We use a multi-loop structure that takes advantage of a broad matching bandwidth and a high vertical radiation gain by efficiently utilizing a given space of a quarter glass in spite of the simple planar structure. Transparency of the antenna is also improved by adjusting the stripline widths based on the induced current distributions. The proposed antenna is printed on a quarter glass of a commercial vehicle and antenna performances such as the return loss and the gain are measured in a semi-anechoic chamber. The result shows the average gain of -9.67 dBi along the bore-sight direction($\theta=90^{\circ}$, $\phi=270^{\circ}$) in the FM radio band(80$\sim$l10 MHz), which is higher than a commercial monopole typed on-glass antenna($G_{ave}$=-12.49 dBi) and micro-antenna($G_{ave}$=-19.24 dBi) mounted on the roof of the RV.