• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.379-380
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• 2016

본 논문에서는 Z-소스 네트워크 기반의 배터리 시뮬레이터의 전압 제어기 설계를 위한 소신호 모델링을 수행하고 보드선도를 이용한 안정도 분석을 통한 전압 제어기 설계 방법을 제안하였다. 이를 통하여 인덕턴스와 커패시턴스에 따라 변하게 되는 시스템의 주파수 응답 특성을 고려하여 Z-소스 네트워크 기반의 배터리 시뮬레이터가 안정적으로 동작하도록 하는 전압 제어기의 제어 이득값을 선정하였다. 제안한 방법은 MATLAB을 이용한 안정도 분석을 통하여 검증되었다.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.6
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• pp.296-301
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• 2002

Modern power systems are very complex and to model them completely is impractical for electromagnetic transient studies. Therefore areas outside the immediate area of interest must be represented by some form of Frequency Dependent Network Equivalent (FDNE). In this paper a method for developing Frequency Dependent AC system Equivalent (FDACSE) using Z-domain rational Function Fitting is presented and demonstrated. The FDACSE is generated by Linearized Least Squares Fitting(LSF) of the frequency response of a Z-domain formulation. This 1 & 2 port FDACSE have been applied to the New Zealand South Island AC power system. The electromagnetic transient package PSCAD/EMTDC is used to assess the transient response of the 1 & 2 port FDACSE developed under different condition (linear load, fault and nonlinear loading). The study results have indicated the robustness and accuracy of 1 & 2 port FDACSE for electromagnetic transient studies.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.1
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• pp.9-15
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• 2021

In multi-string light-emitting diode (LED) driver system, current balancing is crucial because the brightness of LED is directly related to its forward current. This paper presents a novel LED current balancing topology using current-fed Z-source converter. With the proposed structure, currents flowing through two LED strings are automatically balanced owing to the charge-balance condition on capacitors. Operation of the proposed converter is simple and the proposed converter uses only one active switch and one diode. Moreover, low-side gate driving can be used to operate the active switch. To verify the operation of the proposed LED current balancing converter, a prototype is built and tested with different numbers of LEDs.

• Journal of Pharmacopuncture
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• v.21 no.1
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• pp.26-34
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• 2018

Objective: The purpose of this study was to investigate the efficacy and safety of spinal-Z, derived from Peganum harmala seeds and Dracocephalum Kotschyi Boiss leaves, in patients with esophageal and stomach adenocarcinoma, and squamous cell carcinoma of the esophagus. Methods: Sixty-one patients with malignancies of the upper gastrointestinal tract were randomly assigned to one of two groups (treatment or control) in a double-blind fashion. Six capsules of Spinal-Z were prescribed to the patients with the regimen of 600 mg/m2/day, and placebo to the control group, for six months. Results: There were no significant differences between the two groups with regard to age, sex, duration of cancer, type of cancer and family history of cancer. There were significant differences in abdominal pain, heartburn, constipation and vomiting between the two groups, following spinal-Z therapy. Evaluation of drug side effects showed no difference in cough or other respiratory symptoms, itching, headache or dizziness between the two groups, both before and after treatment. Conclusion: This study indicates that Spinal-Z is safe and efficacious in the management of patients with upper gastrointestinal tract cancers.

• The Journal of Information Technology
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• v.6 no.1
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• pp.1-10
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• 2003

In this paper, a public key exponential encryption algorithm for data security of computer network is proposed. This is based on the security to a difficulty of polynomial factorization. For the proposed public key exponential encryption, the public key generation algorithm selects two polynomials f(x,y,z) and g(x,y,z). The enciphering first selects plaintext polynomial W(x,y,z) and multiplies the public key polynomials, then the ciphertext is computed. In the proposed exponential encryption system of public key polynomial, an encryption is built by exponential encryption multiplied thrice by the optional integer number and again plus two public polynomials f(x,y,z) and g(x,y,z). This is an encryption system to enforce the security of encryption with help of prime factor added on RSA public key. The propriety of the proposed public key exponential cryptosystem algorithm is verified with the computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8B
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• pp.768-776
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• 2009

This paper analyses the message complexity of TDMA ad hoc MAC protocols. Since the network resource of ad hoc networks is limited due to the multiple interferences and the contention-based wireless channel, the scalability issue is one of the main research topics in developing ad hoc algorithms. Simulation demonstrates that SMACS protocol has the lowest message complexity, whereas TMMAC has the highest. In addition, it is found that since the effect of unicast dominates in the message complexity compared to other factors with an increasing number of nodes, Z-MAC tends to have the property of linearity, whereas BMA and TMMAC show exponential increases in their complexities.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.592-593
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• 2007

The complexity of modern power systems often makes it impractical to model it in its entirety for electromagnetic transient studies. Therefore areas outside the immediate area of interest must be represented by some form of Frequency Dependent Network Equivalent (FDNE). The advantage of using z-domain fitting is that it can be directly implemented in a digital simulation program without any loss of accuracy. Fitting in the s-domain always requires "discretizing" a continuous system and the inherent approximations. This paper presents z-domain rational function formulation and demonstrates the use of it for the assessment of the transient response of the Lower South Island of New Zealand.

• Journal of the Korean earth science society
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• v.33 no.7
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• pp.596-607
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• 2012

The R-Z relationship is one of important error factors to determine the accuracy of radar rainfall estimation. In this study, we have explored the effect of the R-Z relationships derived from disdrometer data in estimating the radar rainfall. The heavy rain event that produced flooding in St-Remi, Quebec, Canada has been occurred. We have tried to investigate the severity of rain for this event using high temporal (2.5 min) and spatial resolution ($1^{\circ}$ by 250 m) radar data obtained from the McGill S-band radar. Radar data revealed that the heavy rain cells pass directly over St-Remi while the coarse raingauge network was not sufficient to detect this rain event. The maximum 30 min (1 h) accumulation reaches about 39 (42) mm in St-Remi. During the rain event, the two disdrometers (POSS; Precipitation Occurrence Sensor System) were available: One used for the reflectivity calibration by comparing disdrometer Z and radar Z and the other for deriving disdrometric R-Z relationships. The result shows the significant improvement with the disdrometric reflectivity-dependent R-Z relationships against the climatological R-Z relationship. The bias in radar rain estimation is reduced from +12% to -2% and the root-mean squared error from 16 to 10% for daily accumulation. Using the estimated radar rainfall rate with disdrometric R-Z relationships, the flood event was well captured with proper timing and amount.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1239-1245
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• 2009

Currently, so many approaching methods are being developed to optimize the antenna size. In this paper, We fabricated Inverted-F type antenna attaching lumped components to solve the limitation of antenna size. Through experiments, a basic Inverted-F type antenna was fabricated and satisfied the adequate radiation pattern. After this, we researched the effect of antenna varied by matching circuit consist of chip type resistor, inductor, and capacitor. Using that elements, the antenna was matched at aim frequency. The proposed antenna's size is $7\;{\times}\;24\;mm$ that is very small size against the resonance frequence. Measuring the developed antenna, Its return loss was -18dB. Thus, this antenna can be used for Z-wave systems.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.311.2-311.2
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• 2008