• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.6
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• pp.322-329
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• 2000

BIST(Built-in Self Test) has been considered as the most promising DFT(design-for-test) scheme for the present and future test strategy. The most serious problem in applying BIST(Built-in Self Test) into a large circuit is the excessive increase in test time. This paper is focused on this problem. We proposed a new BIST construction scheme which uses a parallel divide-and-conquer method. The circuit division is performed with respect to some internal nodes called test points. The test points are selected by considering the nodal connectivity of the circuit rather than the testability of each node. The test patterns are generated by only one linear feedback shift register(LFSR) and they are shared by all the divided circuits. Thus, the test for each divided circuit is performed in parallel. Test responses are collected from the test point as well as the primary outputs. Even though the divide-and-conquer scheme is used and test patterns are generated in one LFSR, the proposed scheme does not lose its pseudo-exhaustive property. We proposed a selection procedure to find the test points and it was implemented with C/C++ language. Several example circuits were applied to this procedure and the results showed that test time was reduced upto 1/2151 but the increase in the hardware overhead or the delay increase was not much high. Because the proposed scheme showed a tendency that the increasing rates in hardware overhead and delay overhead were less than that in test time reduction as the size of circuit increases, it is expected to be used efficiently for large circuits as VLSI and ULSI.

• Journal of the Korean Statistical Society
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• v.23 no.1
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• pp.179-185
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• 1994

To test the equality of survival distributions in the presence of arbitrary right censorship, the choice of weights which are functions of the number of individuals at risk at the time of each death is very important in increasing the power of the test. In this paper a weight by probit scale is derived and the efficiencies relative to the other weight's are also investigated.

• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.279-285
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• 2002

In this paper we consider the problem of testing for structural changes in ARIMA models based on a cusum test. In particular, the proposed test procedure is applicable to testing for a change of the status of time series from stationarity to nonstationarity or vice versa. The idea is to transform the time series via differencing to make stationary time series. We propose a graphical method to identify the correct order of differencing.

• Proceedings of the Korean Statistical Society Conference
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• 2005.11a
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• pp.43-48
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• 2005

We consider the problem of testing for parameter changes in time series models based on a cusum test. Although the test procedure is well-established for the mean and variance in time series models, a general parameter case has not been discussed in the literature. Therefore, here we develop a cusum test for parameter change in a more general framework. As an example, we consider the change of the parameters in an RCA(1) model and that of the autocovariances of a linear process. We also consider the variance change test for unstable models with unit roots and GARCH models.

• Proceedings of the Safety Management and Science Conference
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• 2004.11a
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• pp.229-235
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• 2004

This paper treats accelerated life tests for automotive connector. The contact resistance of connector is explained by some factors; the use time(calender time, real cycle), stresses and loads adapted in auto test. The relationships between contact resistance and some factors are compared and analyzed by regression models in various test conditions; field use-environment, manufacturer's test environment, and accelerated test condition. The consistency between of manufacturer's test and field test is examined. Finally, the future study on accelerated test for automotive connector is presented.

• Biomedical Science Letters
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• v.19 no.3
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• pp.254-260
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• 2013

The purpose of this study was to survey the effects of Karvonen exercise prescription in coronary artery disease patients reaching age-predicted maximal heart rates with the exercise stress test on hemodynamic responses and cardiorespiratory fitness. The subject group was comprised of acute coronary syndrome (ACS) patients, who were divided into the maximal heart rate (MHR) group that included those who completed the test with their heart rates reaching the number of 220-age and the maximal dyspnea (MD) group that included those who could not continue the test due to respiratory difficulty and were asked to stop the test. Both groups had the exercise stress test before and after the experiment. In the exercise stress test before the experiment, the exercise prescription intensity of Karvonen was set at the target heart rates of 50~85% with a six-week exercise monitoring arrangement. As a result, there were no interactive effects in rest heart rate (RHR) according to time and group, but interactive effects were observed in maximal heart rate (MHR) (P=0.000). Both rest systolic blood pressure (RSBP) and rest diastolic blood pressure (RDBP) had no interactive effects according to time and group. Maximal systolic blood pressure (MSBP) showed significant interactive effects according to time and group (P=0.017). Maximal diastolic blood pressure (MDBP) showed no interactive effects according to time and group, while maximal rate pressure product (MRPP) showed significant interactive effects according to time and group (P=0.003). Maximal time (MT) had no interactive effects according to time and group. $VO_{2max}$ and maximal metabolic equivalent (MMET) showed significant interactive effects according to time and group (P=0.000, P=0.002, respectively), whereas maximal respiratory exchange ratio (MRER) and maximal rating of perceived exertion (MRPE) showed no interactive effects according to time and group. The exercise test that was discontinued as the subjects reached the predicted maximal heart rates considering age did not reach the maximal exercise intensity and accordingly showed low exercise effects when applied to Karvonen exercise prescription intensity. That is, the test should keep going by monitoring cardiac events, MRER and MRPE until the heart rates exceed the predicted MHR by up to 10~12 even after the subject reaches the predicted MHR considering age in the exercise stress test.

• Journal of Aerospace System Engineering
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• v.7 no.3
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• pp.45-50
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• 2013

This is a research report about the method of how to maintain qualification of certification flight test crews. KCA(Korea Certification Agency) have completed the KC-100 airplane certification flight tests which is the first time experienced flight tests operation. After the certification flight test, it has been found that annual flying time requirement of 100 hours to the certification flight test pilot is too strict, and other several requirements to maintain the qualification of the certification test crew such as aircraft certification introduction training, initial flight test pilot and flight test engineer certification training, crew resource management training, aviation physiology training, and survival training was difficult to implement in Korean civil aviation environments. In this study, it was suggested that 30 hours of flying time for maintaining certification flight test pilot qualification could be applied to contribute for safe operation of certification flight test and the other training requirements of the certification flight test crew could be fulfilled using self made training courses, existing FAA training courses and Korean Air Force training resources. Therefore, it is recommended that the regulation of maintaining the certification flight test crew qualification should be refined to implement the requirement practically.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.154-168
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• 2021

COVID-19 has been spreading all around the world, and threatening global health. In this situation, identifying and isolating infected individuals rapidly has been one of the most important measures to contain the epidemic. However, the standard diagnosis procedure with RT-PCR (Reverse Transcriptase Polymerase Chain Reaction) is costly and time-consuming. For this reason, pooled testing for COVID-19 has been proposed from the early stage of the COVID-19 pandemic to reduce the cost and time of identifying the COVID-19 infection. For pooled testing, how many samples are tested in group is the most significant factor to the performance of the test system. When the arrivals of test requirements and the test time are stochastic, batch-service queueing models have been utilized for the analysis of pooled-testing systems. However, most of them do not consider the false-negative test results of pooled testing in their performance analysis. For the COVID-19 RT-PCR test, there is a small but certain possibility of false-negative test results, and the group-test size affects not only the time and cost of pooled testing, but also the false-negative rate of pooled testing, which is a significant concern to public health authorities. In this study, we analyze the performance of COVID-19 pooled-testing systems with false-negative test results. To do this, we first formulate the COVID-19 pooled-testing systems with false negatives as a batch-service queuing model, and then obtain the performance measures such as the expected number of test requirements in the system, the expected number of RP-PCR tests for a test sample, the false-negative group-test rate, and the total cost per unit time, using the queueing analysis. We also present a numerical example to demonstrate the applicability of our analysis, and draw a couple of implications for COVID-19 pooled testing.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.208-210
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• 2003

본 논문은 SOC 내에 존재하는 코아들을 테스트하는 과정에서 개별 코아들의 테스트 조건을 기반으로 한 스케듈링을 통해 최적의 Test ing time을 구하는 연구이다. SOC 내에 존재하는 코아들은 주어지는 TAM(Test Access Mechanism) Width에 따라 각코아들의 Width가 달라지고, 최대 Width에서 최소 Width(1)까지 각 Width 별로 Testing time을 계산할 수 있다. 코아들의 각 Width 별 Testing time을 기존의 Rectangle Packing Algorithm을 수정, 보완하여 효율적으로 구성한 수정 Rectangle Packing Algorithm에 적응하여 최적의 Testing time을 구하는 것이 본 논문의 목적이다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.9 s.339
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• pp.41-50
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• 2005

As the size of circuits becomes larger, the test method needs more test data volume and larger test application time. In order to reduce test data volume and test application time, a new test data compression/decompression method is proposed. The proposed method is based on an XOR network uses don't-care-bits to improve compression ratio during seed vectors generation. After seed vectors are produced seed vectors can be merged using two prefix codes. It only requires 1 clock time for reusing merged seed vectors, so test application time can be reduced tremendously. Experimental results on large ISCAS '89 benchmark circuits prove the efficiency of the proposed method.