우주발사체용 복합재 산화제탱크 구조 강건성 검증을 위한 정하중 시험

김현기,김성찬 항공우주시스템공학회 2021 항공우주시스템공학회지 Vol.15 No.5

This study presented the results of the static load tests conducted to verify the structural robustness of the composite oxidant tank for a space launch vehicle. First, we introduced the test equipment used in the static load test of the composite oxidant tank, and then described the test requirements that the composite oxidant tank must satisfy. In addition, we presented a test set-up diagram consisting of the static load test fixture, hydraulic pressure, control equipment, and data acquisition equipment, and the load profile of the static load test of the composite oxidant tank consisting of shear, equivalent compression, bending, and combination tests. As a result of load control, we verified the reliability of this test by showing the errors between the input load and the feedback load in each channel according to the increase of the test load, and the feedback error between the channel A and channel B of load cell in each load actuator. As a result of the static load test, the load of the actuator was properly controlled within the allowable error range in each test, and we found that the test specimen did not cause damage or buckling that causes significant structural defects in the required load. 본 연구에서는 우주발사체용 복합재 산화제탱크의 구조 강건성을 검증하기 위해 수행된 정하중시험 결과를 제시하였다. 먼저, 복합재 산화제탱크 정하중시험에 사용된 시험장비를 소개하고, 복합재 산화제탱크가 만족해야 하는 시험 요구도를 설명하였다. 그리고, 정하중 시험치구, 유압, 제어장비, 데이터획득장비로 구성되는 시험셋업 구성도를 제시하였고, 전단, 등가압축, 굽힘, 조합시험으로 구성된 복합재 산화제탱크 정하중 시험의 하중 프로파일을 제시하였다. 하중 제어의 결과로 시험하중 증가에 따른 각 하중부과기에서 입력하중과 출력하중 사이의 오차와 각 로드셀 A와 b 채널사이의 오차를 제시하여 본 시험의 신뢰성을 확인하였다. 정하중 시험 결과로, 각 시험에서 하중부과기의 하중은 허용 오차 범위 내에서 적절히 잘 제어되었으며, 시험시편도 요구 하중 내에서 파손이나 심각한 구조적 결함을 유발하는 좌굴은 발생하지 않는 것으로 확인되었다.

정적 분석과 심볼릭 테스팅을 활용한 융합 검증

김은중(Eun-Jung Kim),신승철(Seungcheol Shin),조인준(In-June Jo) 한국콘텐츠학회 2022 한국콘텐츠학회논문지 Vol.22 No.11

화이트박스 테스팅은 블랙박스 테스팅과 달리 주어진 소스코드를 엄밀하게 분석하고 프로그램 동작을 예측함으로써 소프트웨어 오류를 검출하는 방법이다. 그 중에서 정적 분석은 프로그램 값의 근사 기법을 통해 실제 프로그램 동작을 포용함으로써 오류 여부를 예측할 수 있다. 또한 기호 실행은 각 실행 경로에 대한 경로 조건을 만족하는 프로그램 입력 값을 계산함으로써 오류를 발생하는 테스트 케이스를 생성할 수 있다. 하지만 정적 분석은 오탐이 많이 발생하거나 검출했더라도 결함의 근거를 제시하기 어렵다. 또한 기호 실행은 검출해야 하는 오류의 범위를 제어하거나 검출한 오류의 타입을 특정하기 어렵다. 이런 단점을 서로 보완하기 위해 두 기법의 융합을 고려할 수 있다. 본 논문은 화이트박스 테스팅 기법 중에서 정적 분석과 동적 기호 실행을 융합하여 정적 결함을 동적 오류로서 검산하는 방법과 심볼릭 테스팅을 통해 오류 검출 테스트 케이스를 생성하는 방법을 제시한다. 특히 두 개의 상용 도구를 융합하여 정적 결함의 동적 검산을 수행하면서 동시에 단위 테스트를 통해 테스트 커버리지를 얻어내는 결과를 보여준다. 두 도구를 융합하는 접착제는 정적 분석 결과로부터 결함을 검산할 수 있는 명세 코드를 삽입하는 모듈이다. 정적 결함 정보를 이용하여 해당 타입의 명세 패턴을 대입한 명세 코드를 생성하고 소스코드의 명세 위치에 삽입한다. 삽입된 소스코드를 심볼릭 테스팅 도구를 통해 단위 테스트를 수행하면 정적 결함에 해당하는 동적 오류를 발생시킬 수 있고 이때 얻어낸 테스트 케이스는 오류 검출 테스트 케이스가 된다. 이렇게 하면 정적 분석과 심볼릭 테스팅이 순차로 진행되면서 동시에 정적 결함의 검산과 오류의 근거 제시가 가능하다. White box testing can detect software errors by rigorously analyzing a given source code and anticipating its behaviours unlike black box testing. Static analysis as a white box testing can determine static defects by comprehending actual program behaviours with the approximation of program values. On the other, symbolic execution can generate test cases for dynamic errors by calculating program input which satisfy path conditions for each execution path. However static analysis gives a lot of false positives but shows not any proof for static defects. Symbolic execution cannot only identify types of dynamic errors but control the scope of errors. We need to consider a combined method of these techniques for making up these weaknesses. This paper shows a combined testing of static analysis and dynamic symbolic execution by representing how to validate static defects with dynamic errors and how to generate test cases of errors. We specify a method to combine two commercial tools, static analysis tool and symbolic testing tool which carry out the defects validation and unit testing simultaneously. The glue combining two tools is the instrumentation module by which source code is inserted with specification code for validating the corresponding error specification. The instrumented specification code is generated by being instantiated from specification patterns and inserted in the exact location for the corresponding error. With this instrumented source code the symbolic testing tool can execute unit testing and generate test cases for dynamic errors to validate static defects.

KC-100 전기체 정적 구조시험

심재열(Jae-yeul Shim),정근완(Keunwan Jung),이한용(Hanyong Lee),이상근(Sang keun Lee),황귀철(Gui-Chul Hwang),안석민(Seokmin Ahn) 한국항공우주학회 2014 韓國航空宇宙學會誌 Vol.42 No.1

항우연에서는 복합재 소형항공기(KC-100)에 대하여 15가지 전기체 시험조건과 7개의 국부적 시험조건들에 대한 전기체 정적구조시험을 수행하였다. 시험요구도, 시험일정, 시험체 및 더미구조, 시험하중산출, 시험장치, 시험장비 등을 소개하였다. 수십개의 제어채널을 사용하는 전기체 구조시험의 하중제어의 정확도를 살펴보기 위하여 U1의 시험데이터를 분석하였다. 분석결과 각 채널별 데이터 획득된 하중값은 허용오차인 SNPE(Static null pacing error)값 이내에서 잘 유지하고 있음을 보였고 본 논문의 저자가 제안한 시험의 하중제어오차 크기 정의방법을 적용한 결과 U1 시험의 하중제어 오차값이 8.6N 이었고 나머지 전기체 시험조건들에 대한 시험데이터를 분석한 결과도 보였다. 마지막으로 U1시험에서 자세제어장치에서 측정된 반력들이 시험하중 증가와 함께 변하는 것을 보였고 전기체 구조시험에서 반력변화 발생의 요인들에 대하여 기술하였다. A full-scale static test for a composite structure small aircraft (KC-100) was conducted in the KARI. The test includes 15 full-scale test and 7 local test conditions. Test requirements with test schedule, test article with dummy structures, test load generation, test system, and equipment are introduced for the test. Test load data of the 1st test condition(U1) was analyzed to evaluate an accuracy of load control for the test. The analysis results show that load data obtained during test were within tolerance of Static Null Pacing Error(SNPE) and the error value of load control was 8.6N. The error of load controls for the full-scale static test using dozens of actuators was calculated by a method suggested by authors. Test data for all other test conditions is also shown in this paper. Finally, reactions measured from restraint system of the U1 test condition show that the reaction changes as load increment. The factors which may change the change of reactions for a full-scale static test are introduced in this study.

현장재하시험을 통한 강관 매입말뚝의 지지력 안전율 제안

박종전,정상섬,박정식 한국지반공학회 2018 한국지반공학회논문집 Vol.34 No.5

In this study, the static and dynamic load tests were carried out to propose the safety factor of steel prebored and precast piles in weathered rocks. The axial load tests have been conducted on test piles with nominal diameters of 0.508 and 0.457 m. The piles were subject to static loading tests (14 times) and dynamic loading tests (EOID 14times, Restrike 14times). The dynamic loading tests were first executed after the casting of test piles (① initial EOID test). ②In the succeding 28 days from completion of construction, static load tests were performed and ③final restrike tests were carried out after 15 days from the static test. As a result, the bearing capacity based on Davisson method was 15% higher than that of the restrike tests. The bearing capacity of the static load tests were larger than that of the dynamic tests. By comparing the safety factor through various loading tests, the safety factor of dynamic loading tests were suggested to be lowered to 1.75 from the conventional 2.0.

Full-scale static test of small composite aircraft

Shim, Jae-Yeul,Ahn, Seokmin The Korean Society for Composite Materials 2014 Advanced composite materials Vol.23 No.1

This paper addresses the accuracy of test load application and reaction prediction of aircraft full-scale static test. Factors which have an effect on the accuracy of load application have been identified. An effective procedure for installing test article and actuators is proposed to achieve accurate loading direction compared to conventional one. A method to define quality of load control for a full-scale static test is suggested by using root mean square deviation (RMSD) of command-feedback (CMF) values. Test result of U1 test condition for the KC-100 full-scale static test has shown 8.7 N of averaged RMSD value. At the end, an approach to make general equation for reaction to load increment has been presented and reaction can be assumed to have relation of linear to load increment for symmetric load condition. The linear behavior has been shown through a test data of the KC-100 aircraft which has high stiffness of composite material structure. The test result presents that the linear behavior of the reaction has been well corresponding to the linear model.

정적압입 관통 실험을 이용한 복합재 적층판의 고속충격 탄도한계속도 예측

유원영 ( Won Young You ),김인걸 ( In Gul Kim ),이석제 ( Seok Je Lee ),김종헌 ( Jong Heon Kim ) 한국복합재료학회 2013 Composites research Vol.26 No.1

본 논문에서는 유효 면적의 제한이 있는 복합재 적층판의 탄도한계속도를 예측하였다. 탄도한계속도를 예측하기 위해 정적압입 관통실험과 고속충격 실험 그리고 준실험식을 이용하였다. 정적압입 관통실험을 통해 하중-변위 데이터를 취득하고 이를 이용해서 관통에너지를 측정하였다. 고속충격 실험을 통해 실제 관통 속도 및 관통 에너지를 측정하였다. 정적압입 관통실험과 고속충격 실험을 통해 구한 에너지를 이용해 준실험식을 만들고, 준실험식과 고속충돌 실험결과와 비교해 보았다. 위 방법을 이용해 탄도한계속도를 예측하였고 정적압입 관통 실험과 준실험식에 의한 탄도한계속도 예측의 타당성을 확인하였다. The ballistic limit of Carbon/Epoxy composite laminates with the finite effective area are predicted by using the quasi-static perforation test and semi-empirical formula. The perforation energy were calculated from force-displacement curve in quasi-static perforation test. Also, the actual ballistic limit and penetration energy were obtained through the high-velocity impact test. The quasi-static perforation test and high-velocity impact test were conducted for the specimens with 3 different effective areas. In the high-velocity impact test, the air gun impact tester were used, and the ballistic and residual velocity was measured. The required inputs for the semi-empirical formula were determined by the quasi-static perforation tests and high-velocity impact tests. The comparison between semi-empirical formula and high-velocity impact test results were conducted and examined. The ballistic limits predicted by semi-empirical formula were agreed well with high-velocity impact test results.

A Case Study on the Improvement of Software Test Effectiveness through Static Testing

김효영(Hyo Young Kim),한혁수(Hyuk Soo Han) 한국정보과학회 2007 정보과학회논문지 : 소프트웨어 및 응용 Vol.34 No.3

아직까지 소프트웨어 개발조직에서는 사전검증 활동 및 충분한 테스트 설계가 수행되지 않고 있으며, 따라서 개발 초기에 식별, 수정될 수 있는 결함들까지 테스트시 검출되기 때문에 투입 노력 대비 테스트의 효율성은 떨어진다. 이러한 문제의식을 바탕으로 본 논문은 구현이전단계에서의 사전검증이 수행되지 않고, 테스트 케이스 설계가 충분히 진행되지 않은 경우에 테스트의 효율성을 향상시킬 수 있는 방법을 실사례를 통해 제안하고 있다. 테스트 단계에서의 코드 리뷰와 코드 품질 분석을 통해 테스트 우선 순위 선정, 테스트별 테스트 케이스 설계 등의 주요 활동과 테스트팀과 개발팀과의 역할을 구체적으로 제시한다 Not enough verification or enough design of test is not performing in many software developments organization as yet. Therefore, defects that can be detected and corrected during the beginning phases of development are usually found during dynamic testing, it is often observed that testing is inefficient compared to effort for testing. This study aims to suggest a method for effective testing through case study. It is useful in case of not verification and not enough design of test in the previous phase than coding. We show in a concrete way major activities that determine prioritization of testing and level of test case design through static testing, i.e. code review and analysis of code quality. And also we show role between test team and development team.

Evaluating the Accuracy of Load Application for Static Structural Testing of Aerospace Flight Vehicles

심재열 한국항공우주학회 2020 International Journal of Aeronautical and Space Sc Vol.21 No.1

This study introduces a method to evaluate the accuracy of load application in static structural tests of aerospace flight vehicles which use lots of actuators. Test data were collected for this study from typical test conditions of four independent structural tests performed within two decades in this laboratory. The tests included three full-scale aircraft tests and a launch vehicle sub-component test. The accuracy of load application was evaluated by calculating the root mean square deviation (RMSD) of errors normalized by DLL (design limit load). The RMSD range of the normalized error for the three full-scale aircraft tests was 0.27–0.89% and was much larger than the 0.04% obtained for the launch vehicle sub-component test. After analyzing the errors in all 91 loading channels used for the four tests, it was determined that tight adjustment of the load limit valve (LLV), and using actuators with a small load ratio, introduced large errors in load application. Even after excluding undesirable data related to the tight adjustment of the LLV and the use of actuators with less than 3% load ratio, the accuracy of load application for the three full-scale tests was still lower than the results for the sub-component test. The factors which induced the large errors in the full-scale tests were determined to be the large displacement of wing or canard and the use of actuators with small load ratio. RMSDs recalculated after excluding the undesirable data were in the range of 0.26–0.41% for the full-scale tests. The maximum value, 0.41%, can be used as tolerance to confirm the accuracy of load application for the next full-scale tests.

복합재료 조종면의 정하중 구조시험

조숙경,이명건,조창민,이기범 한국항공우주학회 2012 한국항공우주학회 학술발표회 논문집 Vol.2012 No.11

항공기에 장착되는 조종면의 종류는 플랩, 에일러론 등이 있고, 현재 운용중인 대부분의 항공기는 복합재로 제작된 조종면을 장착하고 있다. 본 연구에서는 항공기의 주익에 장착되는 조종면에 대한 구조건 전성을 검증하기 위해 정하중 구조시험을 별도로 수행하였다. 주익에 연결되는 실제 경계조건을 모사한 시험장치를 구성하였으며, 시험조건에 대한 유한요소모델(FEM)을 생성하여 금속재료 피팅 및 복합재료 샌드위치 구조에 대한 구조해석이 수행되었다. 임계하중 조건에 대한 설계제한하중시험(design limit load test: DLLT) 및 설계극한하중시험(design ultimate load test: DULT)을 수행하여 설계하중에 대한 구조건전성을 검증하였으며, 파단시험(design fracture load test: DFLT)을 통해 조종면이 견딜 수 있는 강도를 확인하였다. 시험결과와 해석결과를 비교하여 FEM의 상관성을 입증하였다. The control surfaces of an aircraft consist of flap and aileron. Most of the aircraft which is working has composite control surfaces. The static structural test for the control surface of the large composite wing box was performed to verify the static strength analysis and the design ultimate strength capabilities. The static test was set according to the real boundary condition. The finite element model was made and structural analysis was performed for the metal fitting and composite sandwich structure. The design limit load test and the design ultimate load test were performed and the ultimate strength of the control surface was confirmed by the design fracture load test. The comparison between the test results and the analysis results are presented here and discussed.

155MM 조명탄 방출성능 시험을 위한 지상정치시험기법 연구

이정호,김동희,오용환,지성민 국방기술품질원 2020 국방품질연구논집 Vol.2 No.2

In recent years, it has become increasingly difficult to conduct a launch test condition for ammunition. As the main item of this study, the 155MM illuminating ammunition(M485A2, M118) is a long-term storage (more than 30 years) ammunition, and it is continuously required to check the performance of the storage ammunition through the ASRP test. This study has researched and developed a ground test system to achieve the objectives of minimizing the risks that can occur when firing a flare using a artillery, effectively utilizing a limited test space, and verifying the performance of flare deployment. During the concept design phase of the ground test bed, a static load analysis was performed using finite element analysis, and the test bed manufacturing time was shortened by reflecting the analysis results in the prototype manufacturing process. The flare emission test was conducted by applying the system of this study, and the stability and test efficiency of the ground test bed were confirmed. Using this system, the analysis of the cause of flare malfunction (unreleased, unopened parachute, etc.) has been successfully performed, and it is judged that it can be used for the flare ASRP functional test.