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Daehee Lee,Jung-hun Lee,Reeho Kim 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.8
LID facilities on the green area-sidewalk-road in cities can be applied in different types and forms according to the status and characteristics of a space. There are some limitations of using LID facilities with respect to area, these limitations can overcome by using the suitable combination of LID practices in an area. For this purpose, the Water Cycle Sidewalk (WCS) was used through the connections of various LID techniques. The WCS could manage stormwater runoff and water quality in a space adjacent to green area-sidewalk-road as a part of WCS, a permeable block pavement (PBP) was installed on the sidewalk, and a vertical infiltration pipe (VIP) and an infiltration-storage tank were located underneath the PBP. Runoff on the sidewalk was pre-treated by a first flash treatment facility and then stored in a storage tank for watering the green area. The average infiltration capacity of a PBP with a storage tank under the pavement was 0.30 mm/sec, about 6 times higher than that of a general PBP section. From the results, the infiltration capacity of a single VIP was approximately 0.35 mm/sec. The overall efficiency rate of runoff reduction from this facility was between 50% and 70%. In addition, the rainwater in the Storage Tank analyzed to be appropriate to use water for landscaping.
Navigation Performance Analysis of KASS Test Signals
Daehee Won,Eunsung Lee,Chulhee Choi 사단법인 항법시스템학회 2023 Journal of Positioning, Navigation, and Timing Vol.12 No.4
This paper presents the analysis results of navigation performance of Korea Augmentation Satellite System (KASS) test signals. Performance analysis was performed with Global Positioning System (GPS) and Satellite Based Augmentation System (SBAS) signals received from 7 KASS reference stations. And the performances were analyzed in terms of the signal strength, statistics for each SBAS message, coverage of ionospheric correction, accuracy, integrity, continuity, and availability. In addition, the navigation solutions provided by commercial receiver was analyzed and the performance experienced by general users was presented. Lastly, directions for further improvement of the KASS system were addressed. These performance analysis results can be used to confirm the feasibility of utilizing KASS in user applications.
Combustion Characteristics of Hydrogen-Enriched Propane in a Dump Combustor with a Bluff-Body
Daehee Kim(김대희),Junggoo Hong(홍정구),Hyundong Shin(신현동),Sangmin Choi(최상민) 한국연소학회 2009 KOSCOSYMPOSIUM논문집 Vol.- No.38
Combustion characteristics of a partially premixed flame in a dump combustor were studied to determine the effects of hydrogen enrichment in propane. A bluff-body was used for flame stabilization. Fuel mixtures of hydrogen mole fraction ranging from 0.1 to 0.5 were burnt at ambient pressure within a quartz chamber. Tests were carried out keeping the total reactants flow rate by adjusting the fuel and air flow rates. Fluctuations of pressure were measured by a piezoelectric pressure sensor. Instantaneous flame structure and OH chemiluminescence images were caprured by a High-speed Intensified Charged Coupled Device (HICCD) camera and Intensified Charged Coupled Device (ICCD) camera. It is shown that hydrogen enrichment in propane induces increase of the frequency and amplitude of pressure fluctuations. Flame existence region seems to be very alike, but instantaneous flame behavior for one cycle showed a different moving tendency according to hydrogen enrichment. Also, location of primary reaction zone was changed from the inner recirculation zone to the turbulent shear layer. The reason is that hydrogen-enriched flame has more fast chemical reaction rate compared to the propane flame so chemical aspects take precedence over flow aspects in the hydrogen-enriched flame.
Analysis of Pattern Gain of Compact Directional 16-port Antenna
Daehee Park,Dong-Ho Cho IEEE 2015 IEEE antennas and wireless propagation letters Vol.14 No.-
<P>Up to now, conventional compact antennas have been designed to acquire as much gain as an ideal 6-port polarimetric antenna can obtain. It was recently shown that an achievable number of degrees of freedom (DOF) can be increased regardless of given antenna space. Here, we propose a compact directional 16-port antenna, with a size of about (0.5λ)<SUP>3</SUP> and a radiation frequency of 2 GHz, which allows more than a six-DOF gain to be achieved using pattern gain. We analyze the far field of the proposed 16-port antenna using spherical vector-wave modes and show that the ergodic capacity of the proposed 16-port antenna is close to that of an ideal 16-port antenna.</P>