• Korean journal of applied entomology
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• v.26 no.1 s.70
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• pp.25-30
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• 1987

An unusual disease syndrome, partial stem rot and final blight of the whole plants was observed in sesame, Sesamum indicum L., cultivar Pungnyeonkkae and Kwangsankkae grown in the field. Symptoms progressed from water-soaking continuous banding lesions on one side of stem to producing abundant Fusarium growth on the lesion at late stage of pathogenesis. Although wilting of plants was most frequently observed in sesame seedlings when infected with Fusarium oxysporum, reproduction of the partial stem discoloration and rot was possible by soil inoculation, and wound inoculation in old plants. The disease occurred from late July. Mycological characteristics of the isolate Fusarium oxysporum compared with those reported in sesame suggested that the isolate might be F. oxysporum f. sp. sesame.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.3
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• pp.281-290
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• 2003

Co Evolutionary Structural Design(CESD) Framework is presented, which can deal with the load design and structural topology design simultaneously. The load design here is the exploration algorithm that finds the critical load patterns of the given structure. In general, the load pattern is a crucial factor in determining the structural topology and being selected from the experts어 intuition and experience. However, if any of the critical load patterns would be excluded during the process of problem formation, the solution structure might show inadequate performance under the load pattern. Otherwise if some reinforcement method such as safety factor method would be utilized, the solution structure could result in inefficient conservativeness. On the other hand, the CESD has the ability of automatically finding the most critical load patterns and can help the structural solution evolve into the robust design. The CESD is made up of a load design discipline and a structural topology design discipline both of which have the fully coupled relation each other. This coupling is resolved iteratively until the resultant solution can resist against all the possible load patterns and both disciplines evolve into the solution structure with the mutual help or competition. To verify the usefulness of this approach, the 10 bar truss and the jacket type offshore structure are presented. SORA(Sequential Optimization & Reliability Assessment) is adopted in CESD as a probabilistic optimization methodology, and its usefulness in decreasing the computational cost is verified also.

• Journal of Korean Society of Forest Science
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• v.107 no.3
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• pp.294-304
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• 2018

Since joining the OECD Development Assistance committee in 2010, the Republic of Korea has been continuously striving to promote its international standing. A new era of cooperation is about to open between Korea and Central Asia, with the $25^{th}$ anniversary of the establishment of diplomatic relationship between Korea and Central Asia, and the welcoming the $80^{th}$ anniversary of the Koryoin (Korean) immigration in 2017. Central Asia is also attracting attention with a rapidly growing economy based on the endowed resources. Therefore, Kyrgyzstan and Tajikistan, among others, were investigated in the following statuses: politics, diplomacy, economy, official development assistance and national strategies. In particular, this study suggests the South Korea's Country Partnership Strategy for Forest with the nations by analyzing the forest environment and forest policy regime, and both forest cooperation strategies: 'Ecotourism Projects using a Walnut Forest' in Kyrgyzstan and 'Projects Restoring Forest and Securing Fuel Woods of Degraded Land in Tugai' in Tajikistan.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.7
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• pp.762-768
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• 2003

This paper reports the effects of gain flatness for linearity improvement of feedforward power amplifier fur IMT-2000 band. To investigate the operational characteristics for gain flatness of each amplifier, WCDMA 4FA input signal was used and measured 10 W output power. Especially, linearity improvement for variation of gain flatness of each amplifier was investigated that have an effect on linearity improvement such as delay line, phase, and amplitude imbalances. Variation of gain flatness of main amplifier is 40 MHz and of error amplifier is 40 MHz and 80 MHz bandwidth, respectively. Measured results, gain flatness of main amplifier is less than 1.5 dB and of error amplifier is less than 0.5 dB for more than 20 dB improvement at 5 MHz offset. In addition to that results, the characteristics of feedforward amplifier are drastically varied by gain flatness of error amplifier and it is shown that gain flatness of error amplifier is more important factor for linearity improvement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.207-213
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• 2008

A simplified design procedure for quasi-Yagi antenna arrays using an ultra-wideband balun is presented. The proposed antenna design procedure is based on the simple impedance matching among antenna components: i.e., balun, feed, and antenna This new broadband and high gain antenna array is possible due to the ultra-wideband performance of the balun. As design examples, wideband $1\times4$ and $1\times8$ quasi-Yagi antenna arrays are successfully designed and implemented in Ku-band with frequency bandwidths of about 50 % and antenna gains of 9$\sim$10 dBi and 11$\sim$12 dBi, respectively. And the simulated and measured results demonstrate wide bandwidths and good radiation properties. These antenna arrays can be applied to various phased-array and spatial power combining systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.214-222
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• 2008

The equivalent circuit for the RLH-TL is proposed considering radiation effects due to the inclusion of a series capacitor and shunt inductor in a unit cell for the right/left-handed transmission line(RLH-TL). The design equations to realize a specific phase shift at a given frequency is also provided. The S-parameters for unit cells with N=1, 3, 5, and 10 are analyzed in various aspects based on the EM and circuit simulations especially for the purpose of controlling radiation along RLH-TL's. A modification formula for the radiation rate per unit cell is also proposed for good agreement between the EM and circuit simulation results.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.6
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• pp.48-55
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• 2001

This paper presents a 1.8 GHz CMOS frequency synthesizer with high-speed on-chip pseudo 2-stage ring VCO. We introduce and analysis the conditions in which the ring VCO can oscillate. For high speed operation, we propose the pseudo 2-stage ring VCO that eliminates dummy loads. It can operate up to 1.87 GHz with 0.6 m CMOS process, which shows 21.3% improvement aginst the conventional 4-stage ring VCO in the aspect of the speed. When the frequency synthsizer with the psedo 2-stage ring VCO is locked at 1.85GHz, the jitter measured to 24 psec. The proposed VCO and the frequency synthesizer are directly applicable to high speed clocky synhtesizers.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.9
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• pp.54-58
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• 2011

In this paper a dual-band Class-E power amplifier using Composite Right-/Left-Handed transmission lines and PIN diode is proposed. Dual-band operation is achieved by the frequency offset and nonlinear phase slope of CRLH TL for the matching network of power amplifiers. The proposed power amplifier has been realized by using in the input and the output matching network for high power added efficiency. PIN diode has been used to obtain the dual-band of power amplifier. The measured results show that output powers of 42.17 dBm and 41.43 dBm were obtained at 800 MHz and 1900 MHz, respectively. At this frequency, we have obtained the power-added efficiency(PAE) of 67.84 % and 65.31 % in two operation frequencies, respectively.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.1
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• pp.1-6
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• 2003

Since the scale in pipes reduces the flow rate, a quantitative evaluation of the scale is essential for the proper maintenance of pipes. Guided waves were employed to estimate the amount of scale in water supplying pipes. Using variable angle wedge, several modes of guided waves wire generated and their propagation charcteristics along the pipes with stale were analyzed. It was experimentally observed that the amplitude of F(M,2) modes at $f{\times}d=1.5MHz\;mm$ decreased significantly with increasing amount of scale. The present study showed that F(M,2) modes were optima) to evaluate the scale in water supplying pipes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.833-842
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• 1998

In this paper, a K-band oscillator which is composed of a hair-pin resonator, a GaAs MESFET, and a frequency doubler, is suggested, implemented by HMIC(Hybrid Microwave Integrated Circuits) form, and characterized for its microwave performance. A $\lambda_g$/4 open stub is used in frequency doubler to suppress the fundamental frequency of 9 GHz which is the output of the hair-pin resonator oscillator and output matching network is optimized for its second harmonic freuency of 18 HGz. For the oscillator, the output power of -0.83 dBm, the fundamental frequency suppression of -23 dBc, and phase noise of -86 dBc/Hz at 18.20 GHz are obtained.