오늘날 대 산업분야는 과학 기술의 진보에 따라 비약적인 기술발달을 이루었다. 따 라서, 고객이 요구(Needs)하는 다양한 기능을 구현하기 위해 상당수 부분을 소프트웨 어 중심으로 달성하고 있다. 이렇듯, 과거의 하드웨어 중심의 자동차와 달리 소프트웨 어 중심의 기능 구현이 이행되고 있는 실정이다. 이렇다 보니, 시스템이 보다 복잡해 짐에 따라 시스템을 설계하고 제어하는데 있어서 상당한 어려움이 따르고 있다. 따라 서, 유럽에서는 자동차 분야의 전자제어 장비로 인한 기능안전을 달성하기 위해 ISO26262라는 국제표준을 제정하였다. 국제표준의 제정에 따라 국내 자동차 산업은 차량 시스템을 설계하는데 있어서의 노력, 뿐만 아니라, 기능안전이라는 안전부분을 대비해야하는 상황에 직면하게 되었다. 본 연구에서는 자동차 시스템의 상위 수준의 설계인 개념설계 단계에서 FMEA를 통한 안전성 활동 반영을 통한 하나의 단일화된 개발 방법론을 본 연구를 통해 제시하고자 한다. 따라서, 본 연구를 기반으로 향후 추가 연구를 수행한다면, 국내 자동차 산업, 뿐만 아니라, 대형복합 안전 중시 시스템 으로 확대하여 설계단계에서 안전성을 동시 고려한 시스템 설계 신뢰성 확보를 위해 도움이 될 것으로 기대 된다.

The demand from customers on better products and systems seems to be ever increasing. To meet the demand, the systems are becoming more and more complicated in terms of both scale and functionality, thereby requiring enormous effort in the development. One bright spot of this trend is that such effort has been the driving forces of the remarkable advancement in modern systems development. On the other hand, safety issues appear to be critical in many large-scale systems such as transportation and weapon systems including high-speed trains, airplanes, ships, missiles/rockets launchers, and so on. Such systems turn out to be prone to a variety of faults and thus the resultant failure can cause disastrous accidents. For the reason, they can be referred to as safety-critical systems. The systems failure can be attributed to either random or systemic factors (or sometimes both). The objective of this paper is on how to reduce potential systemic failure in safety critical systems. To do so, a proper system design is pursued to minimize the risk of systemic failure. A focus is placed on the fact that complex systems have a lot of complicated interfaces among the system elements. To effectively handle the sources of hazards at the complicated interfaces and resultant failure, a method is developed by utilizing a design structure matrix. As a case study, the developed method is applied in the design of train control systems.

Modern systems development becomes more and more complicated due to the need on the ever-increasing capability of the systems. In addition to the complexity issue, safety concern is also increasing since the malfunctions of the systems under development may result in the accidents in both the test and evaluation phase and the operation phase. Those accidents can cause disastrous damages if explosiveness gets involved therein such as in weapon systems development. The subject of this paper is on how to incorporate safety requirements in the design of safety-critical systems. As an approach, a useful system structure using the method of design structure matrix (DSM) is studied while reflecting the need on systems safety. Specifically, the effects of system components failure are analyzed and numerically modeled first. Also, the system components are identified and their interfaces are represented using a component DSM. Combining the results of the failure analysis and the component DSM leads to a modified DSM. By rearranging the resultant DSM, a modular structure is derived with safety requirements incorporated. As a case study, application of the approach is also discussed in the development of a military UAV plane.

The environment and requirements of modern war fields have been affected and thus changed by a variety of issues. To this end, the development of safety-critical weapon systems frequently need to meet those changes even in the operational phase. The necessity of the changes may be due to the preparation for mass-production or the request originated from the user military forces. To meet such a need can be even tougher in the development of safety-critical weapon systems since the integration of the requirements for both systems design and systems safety would make it troublesome. To handel the matter in this paper, utilization of architecture DB is proposed. Specifically, the situation in demand has first been analyzed and then a problem-solving process to accommodate the design changes has been constructed. In doing so, the concept of the aforementioned integration is particularly focused on the functional architecture, which could be a core concept of our approach to solving the problem. The result of a case study demonstrating the method studied using a computer-aided systems engineering tool is also presented.

Due to the evolution of war fields to the net-centric one, weapon systems have become very complex in terms of both mission capability and implementation scales. In particular, the net-centric war field is characterized by a set of interconnected and independently operable weapon systems. As such, the individual weapon systems are required to meet the interoperability and thus, assuring it has been becoming more crucial even in the early stage of development. Furthermore, the ever-growing complexity of the weapon systems has attracted a great deal of attention on the safety issues in the operation and development of weapon systems. The objective of the study is on how to assure the interoperability for safety-critical weapon systems while maintaining system complexity. To do so, the approach taken in the paper is to consider the interoperability from the early stage of the development. Specifically, the required functions to satisfy the interoperability are developed first. The functions are then analyzed in order to link the safety requirements to the reliability evaluation, which results in the study of quantifying the effects of the safety requirements on the system as a whole. As a result, we have developed a methodology and procedure on how to assure interoperability while applying the safety requirements in the weapon systems development.

최근 산업기술의 비약적인 발전으로 인해 오늘날 우리가 개발하거나 사용하는 시스템은 기술적 완성도 측면에서 수준이 매우 높아지고 있다. 한편 고속열차, 첨단 신무기체계 등 대형복합 시스템의 경우, 새로운 시스템을 개발하기 위해서는 기존의 단일화된 개발 방법으로는 개발과정 및 개발 후에 많은 문제점이 잠재적으로 존재한다. 따라서, 기존의 시스템 개발방법인 순공학적인 방법뿐만 아니라 역공학, 동시공학 등을 고려한 통합 프로세스의 고려를 통한 접근이 필요한 시점에 와있다. 이러한 통합적인 접근법을 수행하기 위해서는 체계적인 관리가 필수적이다. 따라서 무수히 많은 설계 산출물이 파생되는 오늘날 산출 DB의 체계적 관리 및 접근을 통한 설계의 중요성이 강조되고 있다. 본 연구를 기반으로 향후 추가 연구를 수행한다면, 국내 대형복합시스템의 설계단계에서의 안전성을 동시 고려한 시스템 설계 신뢰성 확보를 위해 도움이 될 것으로 기대 된다.

The recent trend in modern systems development can be characterized by the increasing complexity in terms of both the functionality and HW/SW scale that seems to be accelerated by the growing user requirements and the rapid advancement of technology. Among the issues of complexity, the one related to systems safety has attracted great deal of attention lately in the development of the products ranging from mass-transportation systems to defence weapon systems. As such, the incorporation of safety requirements in systems development is becoming more important. Note, however, that since such safety-critical systems are usually complex to develop, a lot of organizations and thus, engineers should participate in the development. In general, there seems to be a variety of differences in both the breadth and depth of the technical background they own. To address the problems, at first this paper presents an effective design process for safety-critical systems, which is intended to meet both the systems design and safety requirements. The result is then advanced to obtain the models utilizing the systems modeling language (SysML) that is a de facto industry standard. The use of SysML can facilitate the construction of the integrated process and also foster active communication among many participants of diverse technical backgrounds. As a case study, the model-based development of high-speed trains is discussed.

It is becoming more and more important to develop safety-critical systems with special attention. Examples of the safety-critical systems include the mass transportation systems such as high speed trains, airplanes, ships and so forth. Safety critical issues can also exist in the development of atomic power plants that are attracting a great deal of attention recently as oil prices are sky-rocketing. Note that the safety-critical systems are in general large-scale and very complex for which case the effects of adopting the systems engineering (SE) approach has been quite phenomenal. Furthermore, safety-critical requirements should necessarily be realized in the design phase and be effectively maintained thereafter. In light of these comments, we have considered our approach to developing safety-critical systems to be based on the method combining the systems engineering and safety management processes. To do so, we have developed a design environment by constructing a whole life cycle model in two steps. In the first step, the integrated process model was developed by integrating the SE (ISO/IEC 15283) and systems safety (e.g., hazard analysis) activities and implemented in a computer-aided SE tool environment. The model was represented by three hierarchical levels: the life-cycle level, the process level, and the activity level. As a result, one can see from the model when and how the required SE and safety processes have to be carried out concurrently and iterately. Finally, the design environment was verified by the computer simulation.