• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.6
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• pp.77-84
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• 2003

A mobile agent is a program which represents a user in a network and is capable of migrating from one node to another node, performing computations on behalf of the user. In this paper, we suggest a scheme that can safely recover mobile agent using the checkpoint that is saved at the platform that it visited previously and restart its execution from the abnormal termination point of the mobile agent. For security, mobile agent uses its public key to encrypt the checkpoint and the home platform uses the private key of the mobile agent to decrypt the encrypted checkpoints at the recovery stage. When home platform receives the checkpoint of the mobile agent, home platform verifies the checkpoint using message digest. Home platform verifies the correctness of the checkpoint by comparing the message digest generated at checkpoint mention time with the message digest generated at mobile agent recovery time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.1
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• pp.21-30
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• 2022

The restart of scramjet engine is almost impossible in case its unstart happens during engine operation. Therefore, it is essential to prognosticate the scramjet engine unstart phenomena. A numerical simulation of a scramjet engine is conducted to investigate the unstart process of the scramjet engine by adjusting the backpressure at the isolator outlet to the engine analysis environment. The start and unstart of the engine are identified by applying a support vector machine (SVM) through the data measured by wall pressure so that the locations of the pressure sensors most suitable for the unstart detection are selected. And the operation conditions in which the engine is avoid to be unstarted are quantified to perceive the safety margin.

• Journal of Microbiology and Biotechnology
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• v.32 no.3
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• pp.387-395
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• 2022

Deciphering the metabolites of human diseases is an important objective of biomedical research. Here, we aimed to capture the core metabolites of Fanconi anemia (FA) using the bioinformatics method of a multi-omics composite network. Based on the assumption that metabolite levels can directly mirror the physiological state of the human body, we used a multi-omics composite network that integrates six types of interactions in humans (gene-gene, disease phenotype-phenotype, disease-related metabolite-metabolite, gene-phenotype, gene-metabolite, and metabolite-phenotype) to procure the core metabolites of FA. This method is applicable in predicting and prioritizing disease candidate metabolites and is effective in a network without known disease metabolites. In this report, we first singled out the differentially expressed genes upon different groups that were related with FA and then constructed the multi-omics composite network of FA by integrating the aforementioned six networks. Ultimately, we utilized random walk with restart (RWR) to screen the prioritized candidate metabolites of FA, and meanwhile the co-expression gene network of FA was also obtained. As a result, the top 5 metabolites of FA were tenormin (TN), guanosine 5'-triphosphate, guanosine 5'-diphosphate, triphosadenine (DCF) and adenosine 5'-diphosphate, all of which were reported to have a direct or indirect relationship with FA. Furthermore, the top 5 co-expressed genes were CASP3, BCL2, HSPD1, RAF1 and MMP9. By prioritizing the metabolites, the multi-omics composite network may provide us with additional indicators closely linked to FA.

• Korean Journal of Clinical Pharmacy
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• v.27 no.1
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• pp.15-21
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• 2017

Objective: The perioperative management of antithrombotic therapy is often challenging and it requires a fine balance between the risk of hemorrhage and thrombosis. We aimed to evaluate the antithrombotic management for moderate to high risk patients in real world setting. Methods: Among the patients who were consulted to the neurologist for the evaluation of perioperative risk from 2010 to 2012, patients undergoing moderate to high risk surgery and taking antithrombotics within 30 days were identified. We analyzed the timing of discontinuation and reinitiation of antithrombotic drugs before or after surgery as well as the status of bridging therapy. In addition, the conformity with the guideline suggested by American College of Chest Physicians was assessed. The rate of thromboembolic event and major hemorrhage were also investigated. Results: A total of 329 patients were included. The concordance rate of warfarin stop and restart time with guideline was 23.4% and 10.3%, respectively. Continuing aspirin in patients undergoing coronary artery bypass surgery or non-cardiac surgery in patients with high risk for cardiovascular events were 59.2% and 2.6%, respectively. Bridging therapy was adopted in 92.9% and 81.2% in patients who had received anticoagulant before surgery and who were at high and low risk thromboembolism, respectively. In entire cohorts, 30-day incidence of major bleeding and thromboembolic event were 31.9% and 3.0%. Co-morbid renal disease were shown as independent predictor for major bleeding (adjusted OR 2.65. 95% CI 1.33-5.28). Conclusion: The concordance rate with guideline regarding perioperative antithrombotic use was low and bridging therapy was prevalent in patients undergoing moderate to high risk surgery.

• Advances in aircraft and spacecraft science
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• v.5 no.2
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• pp.225-237
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• 2018

The difficulties of satellite vibration testing are due to the commonly expressed qualification requirements being incompatible with the limited performance of the entire controlled system (satellite + interface + shaker + controller). Two features cause the problem: firstly, the main satellite modes (i.e., the first structural mode and the high and low tank modes) are very weakly damped; secondly, the controller is just too basic to achieve the expected performance in such cases. The combination of these two issues results in oscillations around the notching levels and high amplitude beating immediately after the mode. The beating overshoots are a major risk source because they can result in the test being aborted if the qualification upper limit is exceeded. Although the abort is, in itself, a safety measure protecting the tested satellite, it increases the risk of structural fatigue, firstly because the abort threshold has been already reached, and secondly, because the test must restart at the same close-resonance frequency and remain there until the qualification level is reached and the sweep frequency can continue. The beat minimum relates only to small successive frequency ranges in which the qualification level is not reached. Although they are less problematic because they do not cause an inadvertent test shutdown, such situations inevitably result in waiver requests from the client. A controlled-system analysis indicates an operating principle that cannot provide sufficient stability: the drive calculation (which controls the process) simply multiplies the frequency reference (usually called cola) and a function of the following setpoint, the ratio between the amplitude already reached and the previous setpoint, and the compression factor. This function value changes at each cola interval, but it never takes into account the sensor signal phase. Because of these limitations, we firstly examined whether it was possible to empirically determine, using a series of tests with a very simple dummy, a controller setting process that significantly improves the results. As the attempt failed, we have performed simulations seeking an optimum adjustment by finding the Least Mean Square of the difference between the reference and response signal. The simulations showed a significant improvement during the notch beat and a small reduction in the beat amplitude. However, the small improvement in this process was not useful because it highlighted the need to change the reference at each cola interval, sometimes with instructions almost twice the qualification level. Another uncertainty regarding the consequences of such an approach involves the impact of differences between the estimated model (used in the simulation) and the actual system. As limitations in the current controller were identified in different approaches, we considered the feasibility of a new controller that takes into account an estimated single-input multi-output (SIMO) model. Its parameters were estimated from a very low-level throughput. Against this backdrop, we analyzed the feasibility of an LQG control in cancelling beating, and this article highlights the relevance of such an approach.

• Journal of KIISE:Databases
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• v.35 no.3
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• pp.257-271
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• 2008

Wireless broadcast environments has character that a number of mobile client can receive data streaming from central server no matter how they are so many. Because it is asymmetric bandwidth in that uplink and downlink bandwidth are different. This advantage helps wireless broadcast environments is used in many applications. These applications work almost read operation and need control concurrency using transaction unit. Previous concurrency control scheme in single channel is not adapted in multi channel environments because consistency of data are broken when a mobile client tunes in a broadcast cycle in a channel and then move into another channel and listen to different broadcast cycle with already accessed broadcast cycle. In this paper, we propose concurrency control for read-only mobile transactions in multiple wireless broadcast channel. First of all, we adapt index and data dedicated channel and propose LBCPC(Longest Broadcast Cycle Per Channel) as new unit of consistency. In index dedicated channel, it is repeatedly broadcasted data in same BCPC(Broadcast Cycle Per Channel) until LBCPC. And mobile transaction executes validation using control information every LBCPC. As a result, consistency of data is kept and average response time is shorter than one in single channel because waiting time for restart reduces. And as control information is broadcasted more frequently than in single channel, it is guaranteed currency about data accessed by transaction. Finally, according to the simulation result, we verify performance of our scheme in multi channel as comparing average response time with single channel.

• Clinical and Experimental Reproductive Medicine
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• v.16 no.1
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• pp.57-68
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• 1989

Some infertile patients who need IVF-ET for conception have small ovarian cysts diagnosed in pelvic ultrasonography. It is well known that it is impossible or very difficult to perform controlled ovarian hyperstimulation(COH) for such patients because of the poor ovarian response or the possibility of ovarian hyperstimulation syndrome(OHSS). To remove or to decrease the size of ovarian cysts, estrogen and progesterone (E-P) therapy with oral contraceptives for 2 cycles and transvaginal aspiration of ovarian cysts using transvaginal ultrasonography were performed in 36 IVF-cancelled infertile patients with ovarian cysts from February to October, 1988 at Seoul National University Hospital. Thirty-nine ovarian cysts($32.8{\pm}9.6$mm in mean diameter) were treated with E-P therapy, and their size decreased to $28.2{\pm}11.0mm$ after 1 cycle and significantly to $24.8{\pm}14.7mm$ after 2 cycles. After E-P therapy for 2 cycles, 7(17.9%) ovarian cysts disappeared in ultrasonography, 9(23.1%) decreased in size significantly, 18(46.2%) had no change in size and 5(12.8%) increased in size. Thirty-two ovarian cysts($30.2{\pm}9.7mm$) in 30 patients were aspirated transvaginally, and there was no significant decrease in size after follow-up transvaginal ultrasonography($27.8{\pm}12.5mm$). After transvaginal aspiration, 3(9.4%) ovarian cysts disappeared and 28(87.5%) had no change in size. The mean amount of the transvaginally aspirated cystic fluids was $19.6{\pm}13.2ml$, and there was no malignant cells in aspiration cytology. Four endometrioid cysts, one dermoid cyst and one mucinous cyst could be diagnosed in consideration of the findings of transvaginal ultrasonography and the characteristics and cytology of aspirated fluids. Therefore E-P therapy and transvaginal aspiration of ovarian cysts had made it possible to restart IVF program earlier in the IVF-cancelled patients with ovarian cysts.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.178-186
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• 2006

기상 수치예보는 (Numerical Weather Pridiction, NWP)는 바람, 기온, 등과 같은 기상요소의 시간 변화를 나타내는 물리방정식을 컴퓨터로 풀어 미래의 대기 상태를 예상하는 과학적인 방법으로 지구를 상세한 격자 2진부호(GRIdded Binary, 이하 GRIB)로 나누어 그 격자점에서의 값으로 대기 상태를 나타낸다. 지구 각지에서의 각종 관측자료를 기초로 격자점상의 현재값을 구한다. 대용량의 격자데이터는 이진형태이어서 컴퓨터, 서버 저장장치에서 동일형태 데이터로 존재한다. 우리나라 최초의 저궤도 관측 위성인 다목적 실용위성 KOMPSAT-1호(이하, 아리랑 위성1호)는 전자광학카메라(Electro Optical Camera, EOC)를 탑재하여 1999년 12월 21일에 발사된 이후 2006년 1월 현재까지 6여년간 성공적으로 임무를 수행, 7049여회의 영상을 획득하여 국가적으로 귀중한 자료로 활용하고 있다. 아리랑 위성1호는 일일 2-3회 EOC영상을 획득하고 있으며, 임무계획(Mission Planning)은 MP(Mission Planner)가 사용자로부터 자료를 수집하여 임무분석 및 계획 서브시스템(MAPS)에 의해 계산되어진 위성의 제도예측 데이터에 촬영하고자하는 목표지점 좌표를 입력하여 자동명령생성기(KSCG)에 의해 계산된 촬영 경사각도(Tilt)값을 위성에 전송하여 목표지역의 영상을 획득하게 된다. 위성영상 획득에 있어 고가의 위성을 운영하면서 기상의 상태를 정확히 예측하여 실패없이 유효한 영상을 획득하는 것이 무엇보다 중요하다. 본 논문에서는 효율적인 위성임무계획을 위한 기상수치예보 자료를 분석하여 앞으로 발사하게 될 고해상 카메라 탑제위성인 아리랑 위성2호와 3호에 적용하고자 한다. the sufficient excess reactivity to override this poisoning must be inserted, or its concentration is decreased sufficiently when its temporary shutdown is required. As ratter of fact, these have an important influence not only on reactor safety but also on economic aspect in operation. Considering these points in this study, the shutdown process was cptimized using the Pontryagin's maximum principle so that the shutdown mirth[d was improved as to restart the reactor to its fulpower at any time, but the xenon concentration did not excess the constrained allowable value during and after shutdown, at the same time all the control actions were completed within minimum time from beginning of the shutdown.및 12.36%, $101{\sim}200$일의 경우 12.78% 및 12.44%, 201일 이상의 경우 13.17% 및 11.30%로 201일 이상의 유기의 경우에만 대조구와 삭제 구간에 유의적인(p<0.05) 차이를 나타내었다.는 담수(淡水)에서 10%o의 해수(海水)

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.3 s.309
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• pp.9-16
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• 2006

Many image and video compression algorithms work by splitting the image into blocks and producing variable-length code bits for each block data. If variable-length code data are transmitted consecutively over error-prone channel without any error protection technique, the receiving decoder cannot decode the stream properly. So the standard image and video compression algorithms insert some redundant information into the stream to provide some protection against channel errors. One of redundancies is resynchronization marker, which enables the decoder to restart the decoding process from a known state in the event of transmission errors, but its usage should be restricted not to consume bandwidth too much. The Error Resilient Entropy Code(EREC) is well blown method which can regain synchronization without any redundant information. It can work with the overall prefix codes, which many image compression methods use. This paper proposes EREREC method to improve FEREC(Fast Error-Resilient Entropy Coding). It first calculates initial searching position according to bit lengths of consecutive blocks. Second, initial offset is decided using statistical distribution of long and short blocks, and initial offset can be adjusted to insure all offset sequence values can be used. The proposed EREREC algorithm can speed up the construction of FEREC slots, and can improve the compressed image quality in the event of transmission errors. The simulation result shows that the quality of transmitted image is enhanced about $0.3{\sim}3.5dB$ compared with the existing FEREC when random channel error happens.

• Journal of Labour Economics
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• v.24 no.1
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• pp.207-230
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• 2001

This paper uses the Korean Labor Panel data to investigate changes in the employment types of male workers following their job changes with the classification of workers into three categories: regular wage workers, non-regular wage workers, and self-employed workers. It also estimates a competing-risks hazard model to analyze the determinants of employment types of workers. The results show that the type of employment of a worker at an immediate previous job has a critical importance in determining his employment type at a new job and that the types of employment at jobs other than the immediate previous job also play some role in determining the type of employment at a new job, although their impact declines as the number of intervening jobs increases. A job loser, who worked as a non-regular worker at his immediate previous job, for example, is considerably less likely to find a regular job, but more likely to get reemployed at another non-regular job than one who worked as a regular worker at his immediate previous job. Similarly, a worker who quit self-employment is much less likely to find a regular job but more likely to restart his own business than one who worked as a regular worker at his immediate previous job. These findings suggest that it is not easy at all for a worker who worked as either a non-regular worker or self-employed worker to become a regular worker, although it might be premature to assert that non-regular jobs or self-employed jobs are dead-end jobs. Another interesting finding of this analysis is that a high unemployment rate lowers a probability of reemployment at either regular jobs or self-employed jobs, but raises a non-regular job reemployment probability, which strongly implies that as labor market conditions become adverse to workers the proportion of non-regular employment can rise rapidly.