• Journal of the Korean Geographical Society
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• v.46 no.6
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• pp.673-692
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• 2011

Advances in computer technology have enabled us to develop and use numerical landscape evolution models (NLEMs) for exploring the dynamics of geomorphic system from a variety of viewpoints which previously could have not been taken. However, as of yet there have been no trials using or developing NLEMs in Korea. The purpose of this research is to develop a 2 dimensional NLEM on a geological time scale and evaluate its usefulness. The newly developed NLEM (ND-NLEM) treats bedrock weathering as one of the major geomorphic processes and attempts to simulate the thickness of soil. As such it is possible to model the weathering-limited as well as the transport-limited environment on hillslopes. Moreover the ND-NLEM includes not only slow and continuous mass transport like soil creep, but also rapid and discrete mass transport like landslides. Bedrock incision is simulated in the ND-NLEM where fluvial transport capacity is large enough to move all channel bed loads, such that ND-NLEM can model the detachment-limited environment. Furthermore the ND-NLEM adopts the D-infinity algorithm when routing flows in the model domain, so it reduces distortion due to the use of the steepest descent slope flow direction algorithm. In the experiments to evaluate the usefulness of the ND-NLEM, characteristics of the channel network observed from the model results were similar to those of the case study area for comparison, and the hypsometry curve log during the experiment showed rational evidence of landscape evolution. Therefore, the ND-NLEM is shown to be useful for simulating landscape evolution on a geological time scale.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.190-193
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• 2015

The current sea route sign system based on an electronic marine chart only has a data manufacture specification for uses at ECDIS. Therefore, it has a limitation in expressing various sea route data and falls short of productivity as it is frozen to prevent being changed for a long time. Also, it cannot satisfy requirements from high tech such as lattice structure data and time series information. Currently, although it builds each independent operation system based S-57, it has been found that it is the most important requirement from consumers that the entire monitoring system can mutually interwork by standardizing and uniting formats of all protocols. In addition, current status information and alarm system is using AIS, TRS, WCDMA telecommunication and processing all the data after saving it into each different server. Lighthouse lantern which currently has used was utilized to do a performance test of a developed system. All of created data was trasmitted through the RS-232, It is clear that the data was received by a situation monitoring system. In addition, when the data was transmitted after saving in a database, same data was ordinarily received. In this thesis, we will implemented the status information and alarm system of Marine transportation facilities which is a sea route sign system based on S-63 electronic marine chart, S/W, after uniting each different protocol and making combined system.

• Journal of Internet of Things and Convergence
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• v.6 no.2
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• pp.45-50
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• 2020

In this paper, we propose a QoS-based handover management scheme in SDN. Even though there have been lots of recent services such as IoT, the conventional networks provide a monolitic handover method without considerations on flow-specific QoS features. For example, the conventional Internet provides a handover method which only considers IP continuity. On the other hand, 4G and 5G networks use a strict handover method for all kinds of flows with resource reservations. This means that it is difficult to guarantee the QoS requirements for the flow with a strict QoS requirement in Internet and the inefficient resource utilization can occur in the 4G and 5G because of the strict QoS-based handover management. The proposed scheme proposes the flow handover management scheme based on QoS requirements according to the SDN controller's management. From the network operators' perspective, the proposed scheme can provide the efficient resource utilization as well as QoS provisioning.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.522-525
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• 2018

In this paper, we design a UWB / WAS microstrip antenna for wireless local high - speed communication. The substrate of the proposed antenna is FR-4 (er = 4.3) and its size is $30[mm]{\times}30[mm]$. It is designed to have characteristics that can be used in the frequency bands of 3.5 [GHz] and 5.2 [GHz], which are UWB / WAS frequency bands. The simulation was performed using CST Microwave Studio 2014. Simulation results show that the gain is 1.592 [dBi] at 3.5 [GHz] and 2.210 [dBi] at 5.2 [GHz]. The S-parameter also showed a result of less than -10 [dB] (WSWR 2: 1) in the desired frequency band. Microstrip antennas have been miniaturized, high performance, and light weight, and excellent and low cost systems are continuously being developed. In addition, many people use wireless local area network systems used in homes, companies, and public facilities. Since the UWB / WAS technology is proposed according to the development of the system and the demand increase, the antenna that satisfies the above conditions will be designed and the technology applicable to the system will be used more conveniently.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5C
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• pp.527-539
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• 2009

In this paper, we propose an asynchonous ICI (Inter-Cell Interference) mitigation techniques for 3GPP LTE MIMO-OFDMA down-link receiver. An increasing in symbol timing misalignments may occur relative to sychronous network as the result of BS (Base Station) timing differences. Such symbol synchronization errors that exceed the guard interval or the cyclic prefix duration may result in MAI (Multiple Access Interference) for other carriers. In particular, at the cell boundary, this MAI becomes a critical factor, leading to degraded channel throughput and severe asynchronous ICI. Hence, many researchers have investigated the interference mitigation method in the presence of asynchronous ICI and it appears that the knowledge of the SCM (Spatial Covariance Matrix) of the asynchronous ICI plus background noise is an important issue. Generally, it is assumed that the SCM estimated by using training symbols. However, it is difficult to measure the interference statistics for a long time and training symbol is also not appropriate for MIMO-OFDMA system such as LTE. Therefore, a noise reduction method is required to improve the estimation accuracy. Although the conventional time-domain low-pass type weighting method can be effective for noise reduction, it causes significant estimation error due to the spectral leakage in practical OFDM system. Therefore, we propose a time-domain sinc type weighing method which can not only reduce the noise effectively minimizing estimation error caused by the spectral leakage but also implement frequency-domain moving average filter easily. By using computer simulation, we show that the proposed method can provide up to 3dB SIR gain compared with the conventional method.

• The Transactions of the Korea Information Processing Society
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• v.4 no.3
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• pp.754-766
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• 1997

In this paper,we implement the Audit Trail Service Sydtem for the EDI Security.It has solved a law dispute between enterprises by informations that have generated by the EDI serice systrm.The audit trail service sys-tem implemented for EDI security satisfied the requirements of audit and the protocol of the security serive of X.435 and X.400.The EDI Security Audit System consists of the event discrimiator,the audit recirder,the audit archiver,and the provider of audit services .The event discriminator classified the reansmitted data from the EDI network ot audit sercices.The audit recorder constructs an index that has combined time information wiht audit unformations which are classified by the event discriminator.ZThe audit archiver performas the vacumming of added audit imformations by passing time by passing time.The audit provider is a module that carries out the audit trail servies by using stored audit informations. The audit provider suports audit servies,which are non-requdiation,proof and probe,controller of security,and accesing infrimation.The audit trail service system for EDI security constructs audit information by using index that is combining time imfromation,so it supports especially fast accesing audit information.

• KIEE International Transaction on Systems and Control
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• v.2D no.2
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• pp.78-91
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• 2002

In the thermal power plant, there are six manipulated variables: main steam flow, feedwater flow, fuel flow, air flow, spray flow, and gas recirculation flow. There are five controlled variables: generator output, main steam pressure, main steam temperature, exhaust gas density, and reheater steam temperature. Therefore, the thermal power plant control system is a multinput and output system. In the control system, the main steam temperature is typically regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. However, strict control of the steam temperature must be maintained to avoid thermal stress. Maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature versus changes in fuel flow rate, difficulty of control of the main steam temperature control and the reheater steam temperature control system owing to the dynamic response characteristics of changes in steam temperature and the reheater steam temperature, and the fluctuation of inner fluid water and steam flow rates during the load-following operation. Up to the present time, the Proportional-Integral-Derivative Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on the characteristic comparison of the PID controller and the modified 2-DOF PID Controller (Two-Degrees-Freedom Proportional-Integral-Derivative) on the DCS (Distributed Control System). The method is to design an optimal controller that can be operated on the thermal generating plant in Seoul, Korea. The modified 2-DOF PID controller is designed to enable parameters to fit into the thermal plant during disturbances. To attain an optimal control method, transfer function and operating data from start-up, running, and stop procedures of the thermal plant have been acquired. Through this research, the stable range of a 2-DOF parameter for only this system could be found for the start-up procedure and this parameter could be used for the tuning problem. Also, this paper addressed whether an intelligent tuning method based on immune network algorithms can be used effectively in tuning these controllers.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1123-1129
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• 2015

A pair of two-way valves typically is used in automotive washing machines, where the water flow direction is frequently reversed and highly pressurized clean water is sprayed to remove the oil and dirt remaining on machined engine and transmission blocks. Although this valve system has been widely used because of its competitive price, its application is sometimes restricted by surging effects, such as pressure ripples occurring in rapid changes in water flow caused by inaccurate valve control. As an alternative, one three-way reversing valve can replace the valve system because it provides rapid and accurate changes to the water flow direction without any precise control device. However, a cavitation effect occurs because of the complicated bottom plug shape of the valve. In this study, the cavitation index and percent of cavitation (POC) were introduced to numerically evaluate fluid flows via computational fluid dynamics (CFD) analysis. To reduce the cavitation effect generated by the bottom plug, the optimal shape design was carried out through a parametric study, in which a simple computer-aided engineering (CAE) model was applied to avoid time-consuming CFD analysis and difficulties in achieving convergence. The optimal shape design process using full factorial design of experiments (DOEs) and an artificial neural network meta-model yielded the optimal waist and tail length of the bottom plug with a POC value of less than 30%, which meets the requirement of no cavitation occurrence. The optimal waist length, tail length and POC value were found to 6.42 mm, 6.96 mm and 27%, respectively.

• Proceedings of the Korea Society for Simulation Conference
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• 1997.04a
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• pp.65-65
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• 1997

가입자가 B-ISDN(Broadband Integrated Services Digital Network) 서비스에 대한 shb은 수준의 품질 및 안정적인 서비스 제공을 요구함에 따라, 이러한 서비스를 제공하기 위한 ATM (Asynchronous Transfer Mode) 교환기에 대한 신뢰성 설계의 중요성은 증가하 고 있다. 교환기의 중요한 신뢰성 성능 척도 중의 하나인 연결 절단율 (Cutoff connection rate)은 총 연결시간 동안 절단된 연결수로 정의되며, 연결 절단은 호 설정 (Call setup) 단 계를 지나 서비스 중인 연결이 사용자의 요구가 아닌 시스템의 고장으로 종료될 때 발생한 다. 연결 절단율 추정 문제는 기존의 신뢰도 또는 가용도 예측을 위한 시뮬레이션과는 달리 시스템 구성 유니트들의 고장율, 수리율, 그리고 요구된 연결의 트래픽 특성 부분이 혼합된 문제이다. 따라서, B-ISDN 서비스의 중요한 특징인 다양한 트래픽 특성과 시스템의 구성 (Configuration)을 고려하여 연결 절단율을 해석적인 방법을 통하여 추정하는 데네는 어려 움이 있으며 시뮬레이션에 의한 방법이 적절하다. 본 고에서는 B-ISDN 서비스의 트래픽 특 성과 ATM 교환기의 시스템 구성 및 신뢰도 데이터로부터 시스템의 연결 절단율을 추정하 기 위한 시뮬레이터의 기능 및 구조, 시뮬레이션 수행 결과 등을 제시한다. 시뮬레이터는 AweSim 시뮬레이션과 CUser Written Code를 사용하여 개발하였다. 시뮬레이터의 구성 모듈은 크게 호 도착 모듈, 연결 제어 및 자원 할당 모듈, 유니트 고장 및 수리 모듈, 통계 량 수집 모듈 등으로 구성된다. 개발된 시뮬레이터는 B-ISDN 트래픽 파라메터와 연결 절단 율의 상호 관계 규명 및 시스템 설계 대안 (Design alternatives)에 대한 비교/평가에 활용 된다., 수중생물의 경우는 특히 수온, 수량 영양원등이다.(중략). 본 연구의 접근방법으로는 ASRS의 개념적인 Reference Model을 수립하고 이 Reference Model에 대한 Formal Model로 DEVS(Discrete Event System Specification)을 이용하여 시스템을 Modeling하였다. 이의 Computer Simulation을 위하여 DEVS형식론 환경에서의 Simulation Language인 DEVSim ++ⓒ를 이용하여 시스템을 구현하였다.. 실형 결과로는 먼저 선형 상미분방정식의 예로 mass-damper-spring system, 비선형 상미분방정식의 예로는 van der Pol 방정식, 연립 상미분방정식의 예로는 mixing tank problem 등을 보였으며, 그의 공학에서 일어나는 여러 가지 문제들도 다루었다.화물에 대한 방어력이 증가되어 나타난 결과로 여겨지며, 또한 혈청중의 ALT, ALP 및 LDH활성을 유의성있게 감소시키므로서 감잎 phenolic compounds가 에탄올에 의한 간세포 손상에 대한 해독 및 보호작용이 있는 것으로 사료된다.반적으로 홍삼 제조시 내공의 발생은 제조공정에서 나타나는 경우가 많으며, 내백의 경우는 홍삼으로 가공되면서 발생하는 경우가 있고, 인삼이 성장될 때 부분적인 영양상태의 불충분이나 기후 등에 따른 영향을 받을 수 있기 때문에 앞으로 이에 대한 많은 연구가 이루어져야할 것으로 판단된다.태에도 불구하고 [-wh]의미의 겹의문사는 병렬적 관계의 합성어가 아니라 내부구조를 지니지 않은 단순한 단어(minimal $X^{0}$ elements)로 가정한다. 즉, [+wh] 의미의 겹의문사는 동일한 구성요 소를 지닌 병렬적 합성어([$[W1]_{XO-}$ $[W1]_{XO}$ ]$_{XO}$

• Journal of Service Research and Studies
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• v.5 no.2
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• pp.15-24
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• 2015

The trade balance for the information and communications technology (ICT) industries in 2014 have reached 863 hundred million dollars as the main export products such as smart phone and semi-conductor increase, since the ICT industries have played an important role in economic growth in Korea. Until now, the consistent supporting of government and investment of company have been doing with the growth of ICT industries, as a result, Korea marked as the first in the UN electronic government preparing index, and rank 12 in the network preparing index through the policy of national information and basic plan of inter-industry convergence. However, as the unstable international economic circumstances, ICT industries is faced with the stagnation, and then preemptive development of products and services for ICT convergence industries is needed to continually get definite ICT Korea image. In this paper, the ICT convergence industry is analyzed and forecasted. In specific, the international and domestic market for cloud, 3D convergence, and internet of things is diagnosed. The market for ICT convergence industries is predicted to be 3.6 trillion dollar in the world, and 110 trillion won in domestic. From the analytical results for technology and services development, the preemptive supporting of the technology development and policy for the internet of things and 3D convergence industries is required. In addition to, through the future forecasting by socio-tech matrix method, the policy supporting for the ICT convergence area of healthcare, fintech, artificial intelligence, body platform, and human security is needed.