• The Korean Journal of Malacology
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• v.12 no.2
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• pp.91-97
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• 1996

바윗굴의 산란유발 및 종묘생산을 위한 생물학적 기초자료를 얻고자 자극방법별 효과와 난발생 및 유생사육에 미치는 수온의 영향에 관하여 실험한 결과, 자극방법별 산란유발은 정자현탁액 첨가구에서 가장 많은 산란량과 높은 수정률을 나타냈고, 난발생 및 유생사육의 각 단계에 이르기까지의 수온(T, $^{\circ}C$)에 따른 발생속도(h, 시간)는 수온이 높을 수록 빨랐으며, 그 관계식은 다음과 같다. 담륜자기 :1/h= 0.0069T - 0.0950(r=0.9447)D형 유생 :1/h= 0.0006T - 0.0045(r=0.9288)초기 각정기 유생:1/h= 0.0002T - 0.0019(r=0.9358)후기 각정기 유생:1/h= 0.0002T - 0.0022(r=0.9868)부착기 유생:1/h= 0.0001T - 0.0013(r=0.9897)또한 바윗굴의 수온과 난발생 속도와의 관계에서 추정된 난발생의 생물학적 영도는 평균 10.96$^{\circ}C$였으며, 수온별 유생사육시 바윗굴의 생존율은 24$^{\circ}C$에서 6.8%로 가장 좋았다.

• The Korean Journal of Applied Statistics
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• v.33 no.6
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• pp.777-789
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• 2020

COVID-19 has been rapidly spread world wide since late December 2019. In this paper, our interest is to estimate distribution of incubation time defined as period between infection of virus and the onset. Due to the limit of accessibility and asymptomatic feature of COVID-19 virus, the exact infection and onset time are not always observable. For estimation of incubation time, interval censoring technique is implemented. Furthermore, a competing risk model is applied to estimate the case fatality and cure fraction. Based on the result, the mean incubation time is about 5.4 days and the fatality rate is higher for older and male patient and the cure rate is higher at younger,female and asymptomatic patient.

• The Korean Journal of Applied Statistics
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• v.23 no.4
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• pp.715-724
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• 2010

Recurrent event data occurs when a subject experience the event of interest several times and has been found in biomedical studies, sociology and engineering. Several diverse approaches have been applied to analyze the recurrent events (Cook and Lawless, 2007). In this study, we analyzed the YTOP(Young Traffic Offenders Program) dataset which consists of 192 drivers with conviction dates by speeding violation and traffic rule violation. We consider a subject-specific effect, frailty, to reflect the individual's driving behavior and extend to time-varying frailty effect. Another feature of this study is about the redefinition of risk set. During the study, subject may be under suspension and this period is regarded as non-risk period. Thus the risk variables are reformatted according to suspension and termination time.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.505-510
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• 1997

Temperature and light responses on the growth and maturation of gametophytes of Undaria pinnatifida were studied in laboratory culture. The effect of the environmental factors on formation of young sporophyte of U. pinnatifida was also examined in the same culture system. Maximum growth and rapid maturation of the gametophytes were observed at $12:12LD,\;17^{\circ}C$ and 60{\mu}mol\;m^{-2}s^{-1}. However, they survived in a wide range of the examined temperature, light intensity and photoperiod. Particularly they survived under continuous dark condition (0:24LD) until 210 days without any growth and maturation, but died within $10\~40$ days at $30^{\circ}C$. This suggests that optimum rendition for conservation of Undaria gametophytes is under continuous dark photoperiod at $17\~25^{\circ}C$.

• Convergence Security Journal
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• v.12 no.6
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• pp.85-92
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• 2012

There are many software reliability models that are based on the times of occurrences of errors in the debugging of software. It is shown that it is possible to do asymptotic likelihood inference for software reliability models based on infinite failure model and non-homogeneous Poisson Processes (NHPP). For someone making a decision about when to market software, the conditional failure rate is an important variables. The finite failure model are used in a wide variety of practical situations. Their use in characterization problems, detection of outliers, linear estimation, study of system reliability, life-testing, survival analysis, data compression and many other fields can be seen from the many study. Statistical Process Control (SPC) can monitor the forecasting of software failure and there by contribute significantly to the improvement of software reliability. Control charts are widely used for software process control in the software industry. In this paper, we proposed a control mechanism based on NHPP using mean value function of log Poission, log-linear and Parto distribution.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.6
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• pp.483-490
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• 2015

There are many software reliability models that are based on the times of occurrences of errors in the debugging of software. It is shown that it is possible to do likelihood inference for software reliability models based on finite failure model and non-homogeneous Poisson Processes (NHPP). For someone making a decision about when to market software, the conditional failure rate is an important variables. The infinite failure model are used in a wide variety of practical situations. Their use in characterization problems, detection of outlier, linear estimation, study of system reliability, life-testing, survival analysis, data compression and many other fields can be seen from the many study. Statistical process control (SPC) can monitor the forecasting of software failure and thereby contribute significantly to the improvement of software reliability. Control charts are widely used for software process control in the software industry. In this paper, proposed a control mechanism based on NHPP using mean value function of Musa-Okumo and Power law type property.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1272-1277
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• 2010

Target detection and tracking wireless sensor network must have various signal processing ability. Wireless sensor nodes need to light weight signal processing algorithm because of energy constraints and communication bandwidth constraints. General signal processing algorithm of wireless sensor node consists of de-noising, received signal strength computation, feature extraction and signal compression. Wireless sensor network life-time and performance of target detection and classification depend on sensor node signal processing. In this paper, we propose energy efficient signal processing algorithm using wavelet transform. The proposed method estimates exact target position.

• Journal of Korean Society of Transportation
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• v.29 no.3
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• pp.61-72
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• 2011

In the benefits of ITS, there are intangible gains from real-time traffic information as well as classical gains such as travel time saving. These intangible gains are difficult to be estimated by existing transportation investment appraisal commonly used in SOC investment. The major reason is not because of the absence of methodology but because of the absence of generalized values of particular benefits from real time traffic information. This research explores the value of real-time traffic information on VMS that is the most representative of ITS services, by using CVM with Double Bounded Dichotomous Choice Question. Willingness-To-Pay (WTP) functions of drivers are built with survival functions using various types of probability distribution functions such as Exponential, Log-logistic, and Weibull functions. The results reveal that Log-logistic distribution is the most appropriate distribution model to estimate WTP, and the estimated coefficients are stable through LR (Likelihood Ratio) test. For the further study, it is recommended to perform statistical tests of temporal and spatial transferability that is not examined in this research due to the lack of data.

• Korean Journal of Ichthyology
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• v.28 no.1
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• pp.1-8
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• 2016

This study was conducted to investigate the physiological responses of sevenband grouper, Epinephelus septemfasciatus at low temperature condition in winter season. Water temperature was dropped from $12^{\circ}C$ to $5^{\circ}C$ by two different interval (interval I: $-1^{\circ}C/24h$ and interval II: $-1^{\circ}C/8h$). The experimental fishes were exposed for 9 days at each water temperature condition, and were observed survival rate. The blood sample was collected from fishes for analysis of cortisol, glucose, total protein (TP), and electrolytes ($Na^+$, $Cl^-$, $K^+$). Mortality of fish was not observed until $5^{\circ}C$. The mortality (12 individuals) began after 170 h and all fish were death after 174 h in interval I case, whereas the mortality (9 individuals) began after 72 h and all fish were death after 76 h in interval II case. Little different was observed in the physiological responses, but trend was similar between two intervals. The physiological metabolism of plasma cortisol and glucose were increased rapidly, and swimming ability and respiration response was faster at $7^{\circ}C$. This result means that the critical temperature of sevenband grouper was $7^{\circ}C$ at low water temperature condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.432-436
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• 2016

The cooler, which is the main part in a Thermal Observation Device (TOD), makes the TOD function by reducing the temperature. As the cooler is imported, overseas enterprises presented 20,000 hours as the operation time and the military have used the cooler as presented. However, failures have occurred occasionally after mass production stage. Therefore, we need to analyze the MTBF of the TOD cooler. So, military and defense industry companies collected the failure data of the TOD cooler. We analyze the MTBF of the TOD cooler using survival probability function and failure data. We find the optimal distribution by applying parametric method and estimate parameters. We determine that the Log-logistic distribution is the most appropriate for this data. Also, we analyze the reliability per hour of the TOD cooler. The result of MTBF of the TOD cooler was higher than that of presented by oversee enterprises.