Earticle

본 디지털 전환에서 가장 중요한 것은 SW 기술이다. 그러나 많은 기업이 SW 기술 및 인력 확보에 어려움을 겪고 있다. 특히 SW 인력 부족은 더욱 증가할 것이라 보고되고 있다. 정부는 SW 인력 수급정책을 해소하기 위해 인력양성 정책과 많은 지원사업을 수행하고 있지만, 이러한 정책이 효과적으로 수립되기 위해서는 소프트웨어 산 업의 수요와 공급에 대한 정확한 예측이 필수적이다. 따라서 본 연구는 소프트웨어 산업의 수급 불균형을 해소하기 위해 동태적 구조 분석을 수행할 수 있는 시스템 다이내믹스 방법론을 활용하여 시뮬레이션을 개발하였다. 시스템 다이내믹스는 소프트웨어 산업의 인력 수급 불균형 현상에 대해 동태적인 시각에서 그 원인과 정책대안을 찾기에 적절하다. 세부적으로 미국의 노동통계국의(U.S. Bureau of Labor Statistics, BLS) 방법론을 사용하여 적용하여 소프트웨어 산업의 인력 수요 및 공급 예측 모델을 개발하였고, 시나리오 분석을 수행하여 정책적 시사점을 도출하였다.

The most important thing in digital transformation is SW technology. However, many companies are having difficulty securing SW technology and manpower. In particular, it is reported that the shortage of SW manpower will increase further. The government is carrying out manpower training policies and many support projects to resolve SW manpower supply and demand policies, but accurate predictions of demand and supply of the software industry are essential for these policies to be effectively established. Therefore, this study developed a simulation using a system dynamics methodology that can perform dynamic structural analysis to resolve the supply and demand imbalance in the software industry. System dynamics is appropriate to find the cause and policy alternatives from a dynamic perspective on the imbalance in manpower supply and demand in the software industry. In detail, the U.S. Bureau of Labor Statistics (BLS) methodology was used to develop a prediction model for manpower demand and supply in the software industry, and scenario analysis was performed to derive policy implications.

Embedded products are becoming richer in features. Simulation tools facilitate low-costs and the efficient development of embedded systems. SID is an open source simulation software that includes a library of components for modeling hardware and software components. SID components were originally written using C/C++ and Tcl/Tk. Tcl/Tk has mainly been used for GUI simulation in the SID system. However, Tcl/Tk components are hampered by low performance, and GUI development using Tcl/Tk also has poor flexibility. Therefore, it would be desirable to use a more advanced programming language, such as Java, to provide simulations of cutting-edge products with rich graphics. Here, we describe the development of the Java Bridge Module as a middleware that will enable the use of Java Components in SID. We also extended the low-level SID API to Java. In addition, we have added classes that contain default implementations of the API. These classes are intended to ensure the compatibility and simplicity of SID components in Java.

Nowadays, with the advancement of computers, computer simulation linked with VR (Virtual Reality) technology has become a useful method for designing the automotive driving system. In this paper, the VR simulation system was developed to investigate the driving performances of the ASV (Advanced Safety Vehicle) equipped with an ACC (Adaptive Cruise Control) system. For this purpose, VR environment which generates visual and sound information of the vehicle, road, facilities, and terrain was organized for the realistic driving situation. Mathematical models of vehicle dynamic analysis, which includes the ACC algorithm, have been constructed for computer simulation. The ACC algorithm modulates the throttle and the brake functions of vehicles to regulate their speeds so that the vehicles can keep proper spacing. Also, the real-time simulation algorithm synchronizes vehicle dynamics simulation with VR rendering. With the developed VR simulation system, several scenarios are applied to evaluate the adaptive cruise controlled vehicle for various driving situations.

To compute the mean and variance of component-based reliability software, we focused on path-based reliability analysis. System reliability depends on the transition probabilities of components within a system and reliability of the individual components as basic input parameters. The uncertainty in these parameters is estimated from the test data of the corresponding components and arises from the software architecture, failure behaviors, software growth models etc. Typically, researchers perform Monte Carlo simulations to study uncertainty. Thus, we considered a Markov chain Monte Carlo (MCMC) simulation to calculate uncertainty, as it generates random samples through sequential methods. The MCMC approach determines the input parameters from the probability distribution, and then calculates the average approximate expectations for a reliability estimation. The comparison of different techniques for uncertainty analysis helps in selecting the most suitable technique based on data requirements and reliability measures related to the number of components.

This paper proposes two novel methods to model and simulate a mobile Internet of Things (IoT) system using the discrete event system specification (DEVS) formalism. In traditional simulation methods, it is advantageous to partition the simulation area hierarchically to reduce simulation time; however, in this case, the structure of the model may change as the IoT nodes to be modeled move. The proposed methods reduce the simulation time while maintaining the model structure, even when the IoT nodes move. To evaluate the performance of the proposed methods, a prototype mobile IoT system was modeled and simulated. The simulation results show that the proposed methods achieve good performance, even if the number of IoT nodes or the movement of IoT nodes increases.

Enhancing the reliability of the system is important for recent system-on-chip (SoC) designs. This importance has led to studies on fault diagnosis and tolerance. Fault-injection (FI) techniques are widely used to measure the fault-tolerance capabilities of resilient systems. FI techniques suffer from limitations in relation to environmental conditions and system features. Moreover, a hardware-based FI can cause permanent damage to the target system, because the actual circuit cannot be restored. Accordingly, we propose a simulation-based FI framework based on the Verilog Procedural Interface for measuring the failure rates of SoCs caused by soft errors. We execute five benchmark programs using an ARM Cortex M0 processor and inject soft errors using the proposed framework. The experiment has a 95% confidence level with a ±2.53% error, and confirms the reliability and feasibility of using proposed framework for fault analysis in SoCs.

This research presents a three-dimensional modeling technique for a flexible sheet. A relative coordinate formulation is used to represent the kinematics of the sheet. The three-dimensional flexible sheet is modeled by multi-rigid bodies interconnected by out-of-plane joints and plate force elements. A parent node is designated as a master body and is connected to the ground by a floating joint to cover the rigid motion of the flexible sheet in space. Since the in-plane deformation of a sheet such as a paper and a film is relatively small, compared to out-of-plane deformation, only the out-of-plane deformation is accounted for in this research. The recursive formulation has been adopted to solve the equations of motion efficiently. An example is presented to show the validity of the proposed method.

Many daily appliances for examples copiers, printers and ATMs contain the media transport system (MTS) and the slippage between the medium in the MTS deteriorates the performance quality of the whole system. The slippage of the medium in the MTS is affected by many parameters including the friction coefficient between the feeding rollers and the medium, the velocity of the feeding rollers, and the normal force exerted on the medium by feeding rollers. This paper focuses on the effect of the normal force on the slippage while the medium is being fed. For this purpose, we developed a two-dimensional simulation model for a paper feeding system. Using the simulation model, we calculated the slippage of the paper for different normal forces. We have also constructed a testbed of the paper feeding system to verify the simulation results. Experimental results are compared with the simulation results.

Hardware-Software co-simulation of a multiple image encryption technique shall be described in this paper. Our proposed multiple image encryption technique is based on the Latin Square Image Cipher (LSIC). First, a carrier image that is based on the Latin Square is generated by using 256-bits of length key. The XOR operation is applied between an input image and the Latin Square Image to generate an encrypted image. Then, the XOR operation is applied between the encrypted image and the second input image to encrypt the second image. This process is continues until the nth input image is encrypted. We achieved hardware co-simulation of the proposed multiple image encryption technique by using the Xilinx System Generator (XSG). This encryption technique is modeled using Simulink and XSG Block set and synthesized onto Virtex 2 pro FPGA device. We validated our proposed technique by using the hardware software co-simulation method.

Purpose: Since the COVID-19 pandemic, virtual simulation practice has been increasingly activated as an alternative to clinical practice in nursing colleges. This study aimed to provide basic data by confirming changes in self-efficacy and nursing knowledge in the virtual simulations of nursing students, and identifying virtual presence, virtual patient learning system evaluation (VPLSE), and practical satisfaction. Methods: This was a single-group pre-post quasi-experimental study. The subjects were 28 third-grade nursing students. Results: Self-efficacy and nursing knowledge increased significantly (p<.001). Virtual presence had a significant positive correlation with VPLSE) (p=.002) and practice satisfaction (p=.011). There was also a significant positive correlation between virtual simulation learning evaluation and practice satisfaction (p<.001). Conclusion: Based on these results, virtual simulation practice can be used with clinical practice as an educational method to improve nursing students' self-efficacy and nursing knowledge in nursing education. Virtual presence was confirmed as a significant variable to improve practice satisfaction and VPLSE. It is necessary to develop a virtual simulation program that can improve virtual presence through collaboration with virtual reality technology experts.

One of the objectives of any task design is to provide a safe and helpful workplace for the employees. The safety and health module may include means for confronting the design with safety and health regulations and standards as well as tools for obstacles and collisions detection (such as error models and simulators), Virtual Reality is a leading edge technology which has only very recently become available on platforms and at prices accessible to the majority of simulation engineers. The design of an automated manufacturing system is a complicated, multidisciplinary task that requires involvement of several specialists. In this paper, a design procedure that facilitates the safety and ergonomic considerations of an automated manufacturing system are described. The procedure consists of the following major steps. Data collection and analysis of the data, creation of a three-dimensional simulation model of the work environment, simulation for safety analysis and risk assessment, development of safety solutions, selection of the preferred solutions, implementation of the selected solutions, reporting, and training. When improving the safety of an existing system the three-dimensional simulation model helps the designer to perceive the work from operators point of view objectively and safely without the exposure to hazards of the actual system.

One of the objectives of any task design is to provide a safe and helpful workplace for the employees. The safety and health module may include means for confronting the design with safety and health regulations and standards as well as tools for obstacles and collisions detection (such as error models and simulators). Virtual Reality is a leading edge technology which has only very recently become available on platforms and at prices accessible to the majority of simulation engineers. The design of an automated manufacturing system is a complicated, multidisciplinary task that requires involvement of several specialists. In this paper, a design procedure that facilitates the safety and ergonomic considerations of an automated manufacturing system are described. The procedure consists of the following major steps: Data collection and analysis of the data, creation of a three-dimensional simulation model of the work environment, simulation for safety analysis and risk assessment, development of safety solutions, selection of the preferred solutions, implementation of the selected solutions, reporting, and training When improving the safety of an existing system the three-dimensional simulation model helps the designer to perceive the work from operators point of view objectively and safely without the exposure to hazards of the actual system.

집광형태양광발전시스템은 집광형태양전지 셀, 모듈, PCS, 태양위치추적기, 시스템설비와 그에 따른 시스템주변창치들로 구성된다. 이러한 다양한 요소를 반영하여 시스템모델링이 이루어져 집광형태양광발전시스템에 대한 분석과 모델링방법이 적용되어야 한다. 본 논문에서 제안된 이러한 다양한 요소를 반영하여 최적의 CPV 시스템 시뮬레이션을 제안하여 집광형태양광발전시스템 모델링과 에너지의 발생분석에 대한 최적 설계가 이루어지도록 모델링에 중점 두어 설계하였다. 손실 파라미터 계산 방법에 관한 일반화된 집광형태양광발전시스템의 계산 된 시뮬레이션 결과는 높은 신뢰성과 안정성을 갖는 집광형태양광발전시스템의 최적의 설계가 가능하다. 손실 파라미터 계산 방법은 CPV 시스템 설계의 경제적 분석을 위한 시뮬레이션 및 다양한 데이터 활용을 위한 시뮬레이션방법을 활용할 수 있다.

CPV system is composed with CPV cells, modules, PCS(power conditioning system), solar tracker, system installation and balance of systems(BOS). Mention about modelling method which is applied for CPV system simulation and evaluation system analysis. This paper focuses on CPV system modeling and optimal design of the electric energy production analysis through the development of proposed optimal CPV system simulation. Calculated simulation results of the generalized CPV system in regard to loss parameter calculation method can make out optimal configuration of CPV system with high reliability and stability. The loss parameter calculation method establish a mathematical modeling for the purposed of simulation and utilization various data for economical analysis of the CPV system design.

InnovVizwas designed and developed anew as avisualization and simulationtool to present innovation and strategy information. The InnovViz system employs two key types of technology, namely mixed reality (MR) and neural network (NN). An experiment was conducted to examine the usability, acceptance and possible adoption of this new system. Participants comprised 4 experts from 4 top performing entrepreneurial firms and 161 master degree students from 2 leading universities. The study used a modified UTAUT model and a cognition and perception model. The results revealed that when the InnovViz was introduced, the key drivers to adoption are Facilitating Conditions (FC) and Voluntary to Use (VOL). Adequate knowledge and sufficient resources were found to strongly affect FC construct. The expert"fs rating of a firm"fs innovation and performance was more congruent with senior students with a technology-background than with a finance and accounting-background. InnovViz was seen as providing complex information with an ease of use and usefulness for showing data and assessment. Among the three types of visuals depicted by InnovViz, experts rated their usefulness in descending order as follows: Cube, Tetrahedron and Saturn. Finally, experts found backward simulation to be slightly more useful for assessment than forward simulation.

The cryogenic system of RAON which is Korea’s first heavy ion accelerator was numerically modeled and simulated. EcosimPro which is widely used off-the-shelf numerical software for a large scale cryogenic system was used for the simulation. The model of SRF TF cryogenic system, which is the testbed of cryomodule, was firstly established. The integrity of system of SRF TF was confirmed by comparison of simulation and experimental results. The cool-down strategy to minimize the thermal stress of the cavity was simulated and an optimal strategy was established. In addition, the influence of valve and pump control parameters on the cooling time was investigated, and optimal control parameters were also derived. The cryogenic system of SCL3 that is a lowenergy acceleration section including 55 cryomodules, valve boxes, and helium supply lines was also modeled. The soundness of the thermal shield system and interlock system of SCL3 was investigated.

Earthquake was called The Head of Catastrophe in many countries because of its sudden, wide-ranging, and severe loss characteristics. Due to the density of people, economy and buildings in cities, the development and evolution of the earthquake disaster chain presents more complex and varied systemic features. There have been many studies of seismic scenarios, most of which focus on the simulation of the disaster itself, but little attention has been paid to the disaster mechanism and its control methods within the urban system. In the view of urban systemic characteristics, this paper analyzes the evolution and development of earthquake disaster scenarios in urban systems. Based on the interaction of various elements of the urban system, the content system of urban seismic scenario research is clarified. Finally, considering the dual scenarios of disaster and response, an urban seismic scenario construction method is proposed which covers risk assessment, disaster simulation, task and capability matching, emergency preparedness plan. We hope that this research can develop the urban earthquake scenario research and provide reference for the earthquake disaster reduction.

EQPS (Effluent Quality Predication System)로 간헐 주입 SBR (Sequencing Batch Reactor) 운전 성과를 파악하였다. EQPS는 질산화에 대한 pH 영향을 파악할 수 있는 관계로 질산화를 통해 발생된 산을 중화시키기 위한 가성 소다 필요량 을 파악할 수 있다. SBR 후단에 설치된 화학적 인 제거 시설이 인과 고형물을 제거하는 관계로 질소제거가 간헐 주입 SBR 의 주 목적이다. 동일한 유기물량을 1, 2, 3, 3, 4, 5회로 나누어 주입시키는 경우 3회로 나누어 주입하는 경우 질소제거 효 율은 93.1%로 가장 높고, 5회로 나누어 주입시키는 경우는 77.9%로 가장 낮은 것으로 니타났다. 시뮬레이션은 간헐 주입 횟 수가 증가할수록 MLSS농도가 낮아지는 것을 보여주어 간헐 주입을 사용하는 경우, 최적의 질소제거를 위해서는 질산 화에 대한 평가가 선행되어야 한다. 간헐 주입 SBR에서 유입수 분할 횟수는 시뮬레이션을 통해 파악되어야 한다.

The performance of intermittent feed SBR (Sequencing Batch Reactor) was evaluated by simulator called as EQPS (Effluent Quality Predication System). Since the EQPS can simulate the effect of pH on nitrification, the required amount of caustic soda to neutralize acids produced from nitrification can be estimated. Also, chemical phosphorus removal can be simulated. Since the phosphorus and particulate are removed at chemical phosphorus removal unit followed by SBR, the main objective of intermittent feed SBR is nitrogen removal. Five feeding schedule such as 1, 2, 3, 4, and 5 divided feeds with same organic load were studied and the simulation revealed that the 3 divided feed showed the highest percentage of nitrogen removal as 93.1 %, in contrast that the 5 divided feed showed the lowest percentage of nitrogen removal as 77.9 %. Also, simulation revealed that the higher division of feed, the lower the concentration of MLSS (Mixed Liquor Suspended Solid) in SBR. Since the MLSS concentration is inversely proportional to the number of feed, the nitrification that is prerequisite of denitrification has to be carefully evaluated when influent to SBR is divided. Before considering the division of influent to maximize nitrogen removal, the number of division has to be determined by simulation before implementing.