• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3399-3406
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• 2015

NRD(Network RamDisk) is a scheme which allows a system to use the memory of the remote systems just as his own block device via networking. Basically, it consists of a client requesting an NRD access and server providing the NRD. In this paper, we describe the design, implementation and experiment of the block device driver for accessing the NRD in the Linux kernel(2.6) level. First of all, we have analyzed the flow of processing the requests for accessing the block devices in the traditional Linux kernel and figured out the additional functions required for supporting the NRD. Then we have designed and implemented the device diver of NRD client and NRD server for providing these functions. Finally, we have established a NRD server system, and reviewed its functional feasibility by experimenting the requests of NRD access through the NRD device driver implemented on a NRD client.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.4
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• pp.391-396
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• 2008

In this paper, we proposed the new rectangular waveguide-NRD waveguide transition in which the transition function about the standard waveguide is built in within the NRD waveguide ifself. The newly proposed rectangular waveguide-NRD waveguide transition was realized use of NRD waveguide input/output side wall thickness and hole width. In the case of the wall thickness, it was nearly identical with the half of the NRD waveguide guide wavelength and the width of an hole was nearly coincide with the length of the long side of the standard waveguide connected with the NRD waveguide. This kind of the principles is applicable to be unrelated with the frequency band. In this paper, it made in 38 GHz band with the rectangular waveguide-NRD waveguide transition and the feasibility was confirmed. In the back-to-back structure, the rectangular waveguide-NRD waveguide transition manufactured in 38 GHz band has the insertion loss less than 0.4 dB and also has the return loss less than 20 dB.

• The Journal of Natural Sciences
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• v.6 no.1
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• pp.41-48
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• 1993

A cloned delta-endotoxin gene from Bacillus thuringiensis var. kurstaki NRD 6 was mutated at N-terminal toxic portion of the protoxin by site-directed mutagenesis. A Stu 1 restriction site was created in protoxin region of the mutant B.t.kurstaki NRD 6-Stu 1 which changed A to C in 177 region of the protoxin(silent mutation). Antigenic property of crystalline inclusion (delta-endotoxin) of the mutant was no difference to intact strain by the western blot analysis and its toxidity threshold value was also showed 0.015~0.030ng against Choristoneura femiferana-1 insect, similar with 0.01~0.024ng of parent strain, but stronger than that of B.t.kurstaki NRD 5 (500~1000ng) and B.t.kurstaki NRD 4(none toxic).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.741-747
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• 2002

In this paper, NRD guide band pass filter with newly designed inductive iris structure is proposed and analyzed with its test results. In case of common NRD guide filter with air gap coupled structure, it was not easy to fabricate and process or each NRD guide dielectric resonator blocks using PTFE. However, in this our research, each dielectric resonator fabricated in a single NRD guide is coupled with inductive iris located on metal plates. The structure is suitable for mass production of a precise and reliable millimeter-wave filter applications. As a result of measurements, designed NRD guide inductive iris filter has superior performance. The pass band is 38.66~39.06 MHz with 400 MHz bandwidth, insertion loss is about 1.4 dB and return loss is below -18 dB.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.668-676
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• 2010

Optimal net residual dispersions (NRDs) of inline dispersion management (DM) for compensating the signal distortion of $24{\times}40$ Gbps WDM channels in optical transmission links, in which optical phase conjugator (OPC) is placed from 250 km to 750 km by spacing 50 km in 1,000 km total transmission length of single mode fiber (SMF), are induced as a function of various ope positions. And, performance improvement of WDM channels in transmission links with the induced optimal NRD is investigated by comparing with that in transmission links with NRD = 0 ps/nm. It is confirmed that optimal NRDs are decided by displacement of OPC from mid-way of total transmission length, i.e. 500 km, and the determinating and applying of optimal NRD in case of ope displacement into transmitters is more stable and effective than that in case of ope displacement into receivers from 500 km. Also, it is shown that eye opening penalties (EOPs) of WDM channels in transmission links with optimal NRD are improved by 1.5 dB to 3 dB, which are related with OPC position, from that obtained in transmission links with fixed NRD of 0 ps/nm.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.1
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• pp.39-43
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• 2012

60GHz band RF transceiver was made with the NRD waveguide structure for the point- to-point communication. A dielectric line that of comprising NRD waveguide was the milling process was not easy because a material gets soft, and also compression and expansion according to a temperature were serious, so this line was not suitable for the device in which the resonance characteristic was important. In addition, the thing for comprising amplification module was difficult in the NRD waveguide structure. In this paper, a way in which to overcome mentioned in upper part, the transceiver was made by below technology. Components in which the resonance characteristic was not important were made with the NRD waveguide hybrid IC, and components in which the resonance characteristic was important were made with waveguide. An amplifier packaged and modularizing the bare chip, it equipped at the NRD waveguide within. Manufactured transceiver communicated with FDD method, and it had 10dBm output power, and -60dBm minimum receive sensitivity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.990-995
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• 2000

As the interest in the millimeter wave frequency (30 ~300 GHz) increases, Nonradiative Dielectric (NRD) guide is being more attractive due to its low loss characteristics. Most of millimeter wave components, which can be realized with waveguide, can also be realized with NRD guide since NRD guide has similar dispersion characteristics and field patterns to waveguide. Previously, Variational Method was applied to the gap discontinuity problem to design a gap-coupled NRD bandpass filter. In this paper, the design procedure was simplified by replacing the air gap region with an equivalent circuit model of an evanescent waveguide using the fact that the NRD guide has a similar structure with a dielectric-filled metal waveguide. Prior to applying this design method to the bandpass filter of millimeter wave frequency range, a bandpass filter of which center frequency is 10 GHz(3-Pole, 0.1 dB ripple, 2% fractional bandwidth) was designed and fabricated. The measured result agrees with one simulated with HFSS within an error range of a fabrication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.5
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• pp.959-966
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• 2009

Effective transmission distance depending on transmission capacity of WDM systems with inline dispersion management (DM) and optical phase conjugator (OPC) at middle of total transmission length is investigated. The range of net residual dispersion (NRD) resulting 1 dB eye opening penalty (EOP) in 1 Tbps WDM system, in which NRD controlled by only postcompensation, is also investigated. It is confirmed that effective transmission distances are increasedto longer than several hundreds kilometers by applying optimal NRD depending on transmission capacity and distance. And it is confirmed that in 1 Tbps WDM system if NRD is determined to +17 ps/nm, the maximum transmission distance is achieved, and, especially, in long-haul 1 Tbps WDM system the effective NRD range will be determined within positive value.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.3-14
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• 2003

광대역 초고속 통신의 필요성으로 밀리미터파 대역에서 사용 가능한 소자들에 대한 관심이 높아지고 있다. Nonradiative dielectric(NRD) 도파로는 밀리미터파 대역에서 마이크로스트립에 비하여 전파손실이 적고, 금속 도파관에 비하여 집적화에 유리한 장점을 가지고 있다. 이에 밀리미터파 대역의 각종 소자에 사용 가능한 NRD guide에 대한 관심이 높아지고 있다. 본 고에서는 이러한 NRD 도파로를 이용한 대역통과 여파기 및 duplexer의 설계 방법과 EM simulation을 이용한 보정 방법, 그리고 기본적인 형태로부터 응용된 여러가지 형태의 filter 및 duplexer의 특성을 보이고 비교하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.801-809
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• 2010

Limitation of optical phase conjugation for implementation of wideband and long-haul WDM transmission system is symmetric distribution of optical power and local dispersion with respect to optical phase conjugator (OPC). This limitation forces OPC to place at midway of total transmission length. This paper shows that the limitation of optical phase conjugation is overcame by applying optimal net residual dispersion (NRD) into transmission links based in inline dispersion management (DM). Optimal NRD related with OPC position is decided by combination of precompensation and postcompensation. It is confirmed that optimal NRD depends on launch power of WDM channels and system performance criterion as well as OPC position. That is, in case of 1 dB eye opening penaty (EOP) as a performance criterion for WDM channels with 0 dBm launch power, it is confirmed that OPC is allowed to place at anywhere of 1000 km by applying best NRD related with exact OPC position into transmission links. And, it is confirmed that, under 3 dB EOP criterioin for WDM channels with 3 dBm launch power, OPC is allowed to place at 350~700 km by applying NRD between 100 ps/nm and 200 ps/nm into transmission links, though that NRD value is not best combination of precompensation and postcompensation.