• 비파괴검사학회지
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• 제3권2호
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• pp.28-35
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• 1984

• 정보과학회 논문지
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• 제44권2호
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• pp.171-178
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• 2017

본 논문에서는 안드로이드 커널 모듈의 취약점을 탐지하기 위한 자동 유닛 테스트 생성 기법을 제안한다. 안드로이드 커널 모듈의 각 함수를 대상으로 테스트 드라이버/스텁 함수를 자동 생성하고 동적 기호 실행 기법을 사용하여 테스트 입력 값을 자동으로 생성한다. 또한 안드로이드 커널 모듈의 함수 포인터와 함수 선행 조건을 고려하지 않은 테스트 생성으로 인한 거짓 경보를 줄이기 위해 정적 분석을 통한 함수 포인터 매칭 기법과 def-use 분석을 사용한 함수 선행 조건 생성 기법을 개발하였다. 자동 유닛 테스트 생성 기법을 안드로이드 커널 3.4 버전의 세 모듈에 적용한 결과 기존에 존재하던 취약점을 모두 탐지할 수 있었으며 제안한 거짓 경보 감소 기법으로 평균 44.9%의 거짓 경보를 제거할 수 있었다.

• 한국압력기기공학회 논문집
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• 제6권1호
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• pp.16-22
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• 2010

Cast austenitic stainless steel(CASS) is used in the primary cooling piping system of nuclear power plant for it's relative low cost, corrosion resistance and easy of welding. However, the coarse-grain structure of cast austenitic stainless steel can strongly affect the inspectability of ultrasonic testing. The major problems encountered during inspection are beam skewing, high attenuation and high background noise of CASS component. So far, the best inspection performance involving CASS components have been achieved using low frequency TRL(Transmitter/Receiver side-by-side L wave) angle beam probe. But TRL technique could not detect shallow defect and it contains an uncertainty for sizing capability. Currently, most of researchers are studying to overcome these challenge issue. In this study, low-frequency phased array TRL technique used to detect and sizing the flaws in CF8A cast austenitic stainless steel.As conclusion, we could detect and size not only axial flaw but also circumferential flaw using low frequency phased array technique.

• Smart Structures and Systems
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• 제14권6호
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• pp.1269-1289
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• 2014

With the sub-stepping technique, the numerical analysis in real-time dynamic hybrid testing is split into the response analysis and signal generation tasks. Two target computers that operate in real-time may be assigned to implement these two tasks, respectively, for fully extending the simulation scale of the numerical substructure. In this case, the integration time-step of solving the dynamic response of the numerical substructure can be dozens of times bigger than the sampling time-step of the controller. The time delay between the real and desired feedback forces becomes more striking, which challenges the well-developed delay compensation methods in real-time dynamic hybrid testing. This paper focuses on displacement prediction and force correction for delay compensation in the real-time dynamic hybrid testing with a large integration time-step. A new displacement prediction scheme is proposed based on recently-developed explicit integration algorithms and compared with several commonly-used prediction procedures. The evaluation of its prediction accuracy is carried out theoretically, numerically and experimentally. Results indicate that the accuracy and effectiveness of the proposed prediction method are of significance.

• Earthquakes and Structures
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• 제18권3호
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• pp.337-348
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• 2020

Experimental testing has been considered as one of the most straightforward approaches to realize the structural behavior for earthquake engineering studies. Recently, novel and advanced experimental techniques, which combine numerical simulation with experimental testing, have been developed and applied to structural testing practically. However, researchers have to take the risk of damaging specimens or facilities during the process of developing and validating new experimental methods. In view of this, a small-scale structural laboratory has been designed and constructed in order to verify the effectiveness of newly developed experimental technique before it is applied to large-scale testing for safety concerns in this paper. Two orthogonal steel reaction walls and one steel T-slotted reaction floor are designed and analyzed. Accordingly, a large variety of experimental setups can be completed by installing servo-hydraulic actuators and fixtures depending on different research purposes. Meanwhile, a state-of-the-art digital controller and multiple real-time computation machines are allocated. The integration of hardware and software interfaces provides the feasibility and flexibility of developing novel experimental methods that used to be difficult to complete in conventional structural laboratories. A simple experimental demonstration is presented which utilizes part of the hardware and software in the small-scale structural laboratory. Finally, experimental layouts of future potential development and application are addressed and discussed, providing the practitioners with valuable reference for experimental earthquake engineering.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권10호
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• pp.1841-1861
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• 2011

The advance in Service-Oriented Architecture (SOA) and web services has led to the development of new types of a system in which heterogeneous service components can connect and compose to solve a complex business problem. In the SOA, even though these service components are valid in their functionality, there is a need to test their behaviors when those services are composited. In recent years, WS-BPEL has received a wide acceptance as a means of integrating distributed service components. To test the composite service, the existing testing techniques have been focused on the functional features based on the WS-BPEL process. However as SOA approach is applying to real-time software development, the performance of composite service becomes one of important issues. This paper proposes a technique to the performance testing of a composite service with WS-BPEL extension which combined with the concept of aspect. Our WS-BPEL extension has been made towards annotating aspect component which is measuring the response time of the composite service. This paper also explains the procedure of performance testing with on-line transaction system. Our technique can apply to choose an adequate component in service composition with considering the performance among several candidate web service components.

• 한국인터넷방송통신학회논문지
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• 제12권1호
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• pp.123-132
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• 2012

이 논문은 콘콜릭 테스팅을 특화한 목적 지향 테스트 데이터 생성 방법을 제안한다. GCT(Goal-oriented Concolic Testing)라 불리는 제안된한 특정 목표를 실행하는 테스트 입력을 생성한다. 콘콜릭 테스팅은 요구되는 테스트 입력을 발견할 때 까지 모든 가능한 경로 공간을 탐색하는 브루트 포스 방식으로 간주할 수 있다. 대조적으로 GCT는 자료 흐름 정보를 활용하여 목표가 실행되기 위해 먼저 수행되어야 하는 문장들을 식별하여 탐색되는 프로그램 경로의 수를 제한한다. 플래그 변수가 있는 실험을 통해 GCT의 효과성을 보인다.

• 정보처리학회논문지D
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• 제17D권6호
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• pp.423-430
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• 2010

소프트웨어가 대형화 및 복잡화되고 품질보증 및 관리에 대한 요구가 한층 커짐에 따라 소프트웨어 테스트 활동이 중요시되고 있다. 소프트웨어 테스트 활동은 시스템에 존재하는 결함 발견과 처리가 주요 목적이지만, 현재 시스템의 위험요소를 관리하기 위한 요구 또한 존재한다. 하지만 일반적인 테스트 자동화 도구에서는 테스트케이스를 이용하여 동일한 순서로 테스트를 수행하며, 이러한 테스트 방식은 빈번하게 변경되는 소프트웨어를 테스트함에 있어 결함을 조기에 발견할 가능성이 낮아지고 처리되는 시간이 늦어지게 된다. 이에 따라 본 논문에서는 과거 테스트 이력을 이용하여 테스트케이스에 동적인 가중치를 부여함으로써 위험도가 높은 테스트케이스를 우선적으로 테스트 하여 결함을 빠르게 발견할 수 있도록 가중치를 이용한 테스트케이스 동적 관리 기법을 설계하였다.

• 비파괴검사학회지
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• 제26권6호
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• pp.411-416
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• 2006

The critical subject of transverse crack detection in a rail head is treated in this paper. Conventional bulk wave ultrasonic techniques oftenfail because of shelling and other surface imperfections that shield the defects that lie below the shelling. A guided wave inspection technique is introduced here that can send ultrasonic energy along the rail under the shelling with a capability of finding the deleterious transverse crack defects. Dispersion curves are generated via a semi analytical finite element technique along with a hybrid guided wave finite element technique to explore the most suitable modes and frequencies for finding these defects. Sensor design and experimental feasibility experiments are also reported.

• 비파괴검사학회지
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• 제26권6호
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• pp.440-446
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• 2006

The reactor vessel body and closure head are fastened with the stud bolt that is one of crucial parts for safety of the reactor vessels in nuclear power plants. It is reported that the stud bolt is often experienced by fatigue cracks initiated at threads. Stud bolts are inspected by the ultrasonic technique during the overhaul periodically for the prevention of failure which leads to radioactive leakage from the nuclear reactor. The conventional ultrasonic inspection for stud bolts was mainly conducted by reflected echo method based on shadow effect. However, in this technique, there were numerous spurious signals reflected from every oblique surfaces of the thread. In this study, ultrasonic phased array technique was applied to investigate detectability of flaws in stud bolts and characteristics of ultrasonic images corresponding to different scanning methods, that is, sector and linear scan. For this purpose, simplified stud bolt specimens with artificial defects of various depths were prepared.