• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.461-475
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• 2006

In this paper, it is described about the tri-band mobile antenna system design to provide broadband multimedia and direct broadcasting services using goo-stationary Koreasat 3, simultaneously operated in Ka/K/Ku band. The radiating part of the antenna system with a fan beam characteristic in the elevation plane is composed of the quasi-offset dual shaped reflector and the tri-band feeder. The tri-band feeder is also composed of the Ka/K dual band feeder with the protruding dielectric rod, the circular polarizer, the ortho-mode transducer and the circular-polarized Ku band feed array. Especially, the Ka/K dual band circular polarizer was realized firstly using the comb-type structure. For fast satellite-tracking on the movement, the Ku band feed array has the structure of the $2{\times}2$ active phased array which can make electrical beams. And, the circular-polarized characteristic in the feed array was improved by $90^{\circ}$ rotating arrangement of four radiating elements polarized circularly by a $90^{\circ}$ hybrid coupler, respectively. Four beam forming channels to make electrical beams at Ku band are divided into the main beam channel and the tracking beam channel in the output, and noise temperature characteristics of each channel were analyzed on the basis of the contributions of internal sub_units. From the fabricated antenna system, the output power at $P_{1dBc}$ of Ka_Tx channel was measured more than 34.1 dBm and the measured noise figures of K/Ku_Rx channels were less than 2.4 dB and 1.5 dB, respectively, over the operating band. The radiation patterns with co- and cross-polarization in the tri-band were measured using a near-field measurement in the anechoic chamber. Especially, Ku radiation patterns were measured after correcting each initial phase of active channels with partial radiation patterns obtained from the independent excitation of each channel. The antenna gains measured in Ka/K/Ku band of the antenna system were more than 39.6 dBi, 37.5 dBi, 29.6 dBi, respectively. And, the antenna system showed good system performances such as Ka_Tx EIRP more than 43.7 dBW and K/Ku_Rx G/T more than 13.2 dB/K and 7.12 dB/K, respectively.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.82-90
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• 2007

In an attempt to establish the appropriate ventilation device for the bottle culture of king oyster mushroom (Pleurotus eryngii), we investigated carbon dioxide concentration and fruiting body formation according to the various ventilation systems within the mushroom house. In addition to, the efficiency of air circulation and growth rate as well as the appearance of physiologically abnormal phenotypes during their growth stage were also evaluated. four different ventilation devices, parallel-pressure type, positive-pressure type, negative-pressure type, and positive- and negative-pressure type were applied in this study. The positive-and negative-pressure type showed the highest efficiency of air circulation as $CO_2$ concentration was 800 ppm and the level of air current was relatively low compared to the other types (the $CO_2$ concentration of parallel-pressure type was 1,400 ppm). Moreover, the stipe length, the cap diameter, yield, and general quality grown in positive- and negative type ventilation device were also better than in the other three devices though it took slightly longer period for harvesting (18.4 days) than the others (17.6, 17.9 and 18.3 days). The appearance of physiologically abnormal phenotypes such as fruiting body lump, soft rot, and brown rot were significantly decreased in positive-and negative type compared to other types, while the appearance rates were not much different for other symptoms of bacterial ooze, stipe limb and stipe bumpy. In summary, we propose that the optimal ventilation system for the bottle culture of king oyster mushroom is positive- and negative type, and this device is expected to increase the total quality as well as yield all year around.

• Journal of Korean Medical classics
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• v.19 no.1 s.32
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• pp.47-109
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• 2006

서양의학상인위남녀근근시재생식기부동적인(西洋醫學上認爲男女僅僅是在生殖器不同的人). 최근(最近), Legato, Marianne J.박사창립료(博士創立了)‘성인지의학(性認知醫學)’학(學), 개시인식도남녀적차이(開始認識到男女的差異), 주장남녀재치료방법상역부동법(主張男女在治療方法上亦不同法), 종이저일연구진입도료신적단계(從而這一硏究進入到了新的段階). 단시한의학종(但是韓醫學從)${\ulcorner}$황제내경(黃帝內經)${\lrcorner}$개시(開始), 취인위남녀재구조상유근본적차이(就認爲男女在構造上有根本的差異), 이차재생리(而且在生理), 병리(病理), 진단(診斷), 치료상야부동(治療上也不同). 기록한의학기본원리적주역적상관서적화(記錄韓醫學基本原理的周易的相關書籍和)${\ulcorner}$황제내경(黃帝內經)${\lrcorner}$, 이급역대적주요한의서적급종사임상적한의사적서적상(以及歷代的主要韓醫書籍及從事臨床的韓醫師的書籍上), 역도인위남녀유차이(亦都認爲男女有差異). 관어남녀적생성(關於男女的生成), 재(在)${\ulcorner}$보제방(普濟方) 방맥총론(方脈總論)${\lrcorner}$적변남녀형생신육론중제출료(的辨男女形生神毓論中提出了男女的形成有異). ${\ulcorner}$동의보감(東醫寶鑑)${\lrcorner}$여기타한의서부동(與其他韓醫書不同), 불시이질병위주(不是以疾病爲主), 이시이신위중심(而是以身爲中心), 즉목차안형상진행료배열(卽目次按形象進行了排列), 차상세지언급료남녀(且詳細地言及了男女). 나요남녀시고정불변적마 불시적(不是的). ${\ulcorner}$동의보감(東醫寶鑑) 신형장부론(身形臟腑論)${\lrcorner}$인위(認爲)‘인적형색유차이(人的形色有差異), 장부이유이(臟腑易有異), 고외증수동(故外症雖同), 치법인인이이(治法因人而異).’ 안형상선용부동적치법적관점(按形象選用不同的治法的觀点), 이통과주단계지언이표명(已通過朱丹溪之言而表明). 불변관점상여자체격소이동(不變觀点上女子體格小易動), 남자체격대이와(男子體格大易臥). 남자속양기이산(男子屬陽氣易散). 여남자정서초차(如男子情緖稍差), 즉음주해수(卽飮酒解愁), 불이득우울증(不易得憂鬱症). 응보기정기(應補其精氣). 여자속음기이울체(女子屬陰氣易鬱滯), 다유인기지성질(多有忍氣之性質), 이득우울증(易得憂鬱症), 고다용산기약(故多用散氣藥). 간단이언(簡單而言)‘남자위병허증(男子爲病虛證), 여자위병실증(女子爲病實證).’ 종변화적관점래용약(從變化的觀点來用藥), 예여남자수소가용여자약적사물탕(例如男子瘦小可用女子藥的四物湯). 여자비가용남자약적사군자탕(女子肥可用男子藥的四君子湯). 여자골장가용남자약적육미지황환(女子骨壯可用男子藥的六味地黃丸). 위료갱용역이해(爲了更容易理解)‘남녀불변화변화적관점재의학적운용(男女不變和變化的觀点在醫學的運用)’, 이임상병례진행설명(以臨床病例進行說明). 재임상상통과형색맥증적합일화변증론치결정처방(在臨床上通過形色脈證的合一和辨證論治決定處方). 즉불능단순적인위(卽不能單純的認爲), 인위시남자취용육미지황환(因爲是男子就用六味地黃丸), 여자취용사물탕(女子就用四物湯). 남자약소가용사군자탕(男子若小可用四君子湯) 사물탕(四物湯) 육미지황탕(六味地黃湯), 이여자약대가용사군자탕(而女子若大可用四君子湯) 이진탕(二陳湯) 평위산(平胃散) 육군자탕(六君子湯). 인차(因此) 남녀재구조(男女在構造) 생리(生理) 병리유근본성차이(病理有根本性差異), 불이형상래구분(不以形象來區分), 용약상시지불변적입장(用藥上是持不變的立場), 이이형상용약(而以形象用藥), 시종변화적입장래고려적(是從變化的立場來考慮的). 인위이남녀위기준종사임상(認爲以男女爲基準從事臨床), 시부합한의학기본원리지음양관(是符合韓醫學基本原理之陰陽觀).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.7 s.110
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• pp.694-705
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• 2006

In this paper, the linear active phased array antenna system operated in Ku DBS band was designed and experimented. The antenna system was composed of sixteen radiating active channels and Wilkinson power combiners with 16-channel inputs, a stabilizing DC bias and phase control board. Electrical beams of the antenna system can be formed by controling the phase-states of 3-bit digital phase shifter inside each active channel by virtue of the phase control board. The amplitude and phase deviations measured between active channels were less than ${\pm}0.8dB$ and ${\pm}15^{\circ}$, respectively, and the noise figure of each active channel was measured less than 1.2 dB in the operating band. The measured performances of the overall antenna system showed the antenna gain of more than 23.07 dBi and the sidelobe level of less than -11.17 dBc, and the bore-sight cross-polarization level of less than -12.75 dBc in the operating band. Also, by phase-controlling active channels, the beam scan patterns at $10^{\circ},\;20^{\circ},\;30^{\circ}$ were measured, and the losses caused by the corresponding beam scanning were 1.1 dB, 2.5 dB and 3.6 dB from the measurements, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.334-341
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• 2016

In this paper, the study of a waveguide aperture-coupled feed-structured antenna has been conducted for the purpose of applying it to a wireless back-haul system sufficient for high-capacity gigabits-per-second data rates. For this study, a $32{\times}32$ waveguide slot sub-array antenna with a corporate-feed structure was designed and produced. Also, this antenna is used at 57 GHz to 66 GHz in the V-band. The construction of the antenna is a laminated form with radiating parts (outer groove and slot, cavity), a coupled aperture, and feeds in each. The antenna was designed with HFSS, which is based on 3D-FEM, produced with aluminum processed by a precision-controlled milling machine, and assembled after a silver-plating process. The measurement result from analysis of the characteristics of the antenna shows that return loss is less than -12 dB, VSWR < 2.0, and a wide bandwidth ranges up to 16%. An overall first side lobe level is less than -12.3 dB, and a 3 dB beam width is narrow at about $1.85^{\circ}$. Also, antenna gain is 38.5 dBi, offering high efficiency exceeding 90%.

• The Journal of the Acoustical Society of Korea
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• v.24 no.6
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• pp.317-324
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• 2005

Detection and localization of a quiet target in shallow water environments is a challenging problem because of the complicated acoustic Propagation and the Prevalence of loud surface ship interference. Matched Field Processing (MFP) can help address the concern by using a Propagation model to determine the steering vectors, thus Providing optimal away gain and localization accuracy. However, Performance of MFP have yet realized in practice, for several reasons. The most important limitation is that precise information on the underwater environments is generally not available. To examine the Performance of MFP in the East Sea of Korea, we have accomplished a series of matched acoustic Properties and localization experiment (MAPLE). We analyzed the array data measured from MAPLE which is accomplished using a vertical line array and a towed acoustic source off the east cost of Korea in Oct. 2003. We localized the acoustic source using MFP. It is well known that the temperature structure in the experimental site is affected by the short period fluctuation such as internal wave. In this paper, it is found that the sidelobe level on the MFP ambiguity surface is increased being affected by the short period fluctuation.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.385-390
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• 2004

In this paper, we designed a 4-bit optical true time-delay(TTD) for phased array antennas(PAAs), which is composed of a wavelength-fixed optical source, 2 ${\times}$ 2 optical MEMS switches, and fiber-optic delay lines. A 4-bit TTD with a unit time delay difference of 6 ps for 10-GHz PAAs has been implemented. Measurement results on time delay show an error of -0.4 ps at maximum, corresponding to a radiation angle error of less than 1.63$^{\circ}$. Thus, the TTD implemented in this research performs in excellent agreement with theory. Each TTD line, composed of MEMS switches and fiber-optic delay lines, connected to the corresponding antenna element has insertion loss in between 1.36 ㏈ and 2.40 ㏈ depending upon the setup of the switches. On the other hand, the insertion loss difference between TTD lines was 0.32 ㏈ at maximum for a fixed radiation angle. The TTD structure proposed in this paper might be more reliable and economical than those previously proposed using tunable wavelength sources if proper power equalization either with gain control of RF amplifiers or variable attenuators is achieved.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.6
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• pp.613-624
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• 2011

An MMIC multi-function chip for an X-band active phased array radar system has been designed and fabricated using a 0.5 ${\mu}m$ GaAs p-HEMT commercial process. A digital serial-to-parallel converter is included in this chip in order to reduce the number of the control interface. The multi-function chip provides several functions: 6-bit phase shifting, 6-bit attenuation, transmit/receive switching, and signal amplification. The fabricated multi-function chip with a relative compact size of 24 $mm^2$(6 mm${\times}$4 mm) exhibits a transmit/receive gain of 24/15 dB and a P1dB of 21 dBm from 8.5 GHz to 10.5 GHz. The RMS errors for the 64 states of the 6-bit phase shift and attenuation were measured to $7^{\circ}$ and 0.3 dB, respectively over the frequency.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.287-294
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• 2005

In this paper, an optical true time-delay (TTD) for two-dimensional (2-D) phased array antennas (PAAs), composed of a multi-wavelength optical source and a fiber optic delay line matrix consisting of $2\times2$ optical switches with optical fiber connected between cross ports, has been proposed. A 2-bit $\times4-bit$ optical TTD for 10-GHz 2-D PAAs has been implemented by cascading a wavelength dependent TTD (WD-TTD) and a wavelength independent TTD (WI-TTD). The unit time delay for WD-TTD and WI-TTD have been chosen as ${\Delta}T=12ps$ and $\Delta\tau=6ps$, respectively. Time delay have been measured at all radiation angles. The maximum delay error for WD-TTD was measured to be 3 ps due to jitter incurred from gain switching. For the case of WI-TTD, error was within ${\pm}\;1\;ps$. The proposed optical TTD for a 2-D PAA has the following advantages: 1) higher gain compared to one-dimensional linear PAAs, 2) stabilization of optical power and wavelength by using a multi-wavelength optical source, and 3) fast beam scan and simple operation due to electronic control of the $2\times2$ optical switches matrix on a column-by-column basis.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.4
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• pp.61-70
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• 2008

This paper designed the antenna for collecting and servicing the traffic information that apply to freeway Traffic Management System, as using DSRC (Dedicated Short Range Communication). Active DSRC is the technology that is using 5.8GHz Radio Frequency to a mean Sequency and there are a lot of the case occurring a physical electric wave shadowing because of the traveling straight of a electric wave. In such inferior communication environment, it constructed the stabilized communication link that can do collecting and servicing the correct traffic information and designed the beam pattern considering the establishment position of the antenna that can apply to various road environments and a communication area. By considering the communication link environment, this paper designed and manufacture the mean frequency of 5.8GHz, the input loss of -17dB in 75MHz bandwidth, the Axial ratio of 1.5:1, and $2{\times}4$ array microstrip antenna which beam pattern have the characteristic of $55^{\circ}$ horizontal half power beam width and $26^{\circ}$elevation half power beam width and the minimum establishment height of the antenna was designed as 14m for avoiding electric wave shadowing on a physical condition between vehicles