• Journal of the Korean Data and Information Science Society
• /
• v.28 no.5
• /
• pp.1077-1085
• /
• 2017

In this study, we have found the major factors which affect Korean women's wage analysing the data provided by 2015 Korea Labor Panel Survey (KLIPS). In general, wage data is difficult to analyze because random sampling is infeasible. Heckman sample selection model is the most widely used method for analysing the data with sample selection. Heckman proposed two kinds of selection models: the one is the model with maximum likelihood method and the other is the Heckman two stage model. Heckman two stage model is known to be robust to the normal assumption of bivariate error terms. Recently, Marchenko and Genton (2012) proposed the Heckman selectiont model which generalizes the Heckman two stage model and concluded that Heckman selection-t model is more robust to the error assumptions. Employing the two models, we carried out the analysis of the data and we compared those results.

• Journal of Software Assessment and Valuation
• /
• v.15 no.2
• /
• pp.85-93
• /
• 2019

In an open, heterogeneous environment based on machine-to-machine (M2M) interactions, service selection is a critical issue and the concept of social trust can be applied to service selection so that IoT devices can make the best choice for interaction. In this paper, we propose a method for evaluating the trust level of the service and for estimating the QoS of the composite service using a profile created based on social trust relationship in IoT environment. As the service selection is made through quantitative evaluation, it is expected that the result of a more reliable service combination can be obtained.

• Journal of Korean Society of Transportation
• /
• v.26 no.1
• /
• pp.191-201
• /
• 2008

It has been employed TRANSYT-7F and NETSIM to evaluate the validity and effectiveness of improvement on TSM(Transportation Systems Management). But T7F is hard to describe platoon compression and dispersion in actually, and NETSIM takes a long time for network coding, calibration and have difficulty in setting up saturation flow. While Shockwave Model have advantage which can describe platoon compression and dispersion in actually and shorten hours, convenience of application. But Shockwave Model apply unrealistic traffic flow relation ship(U-K curve) and simplify platoon because of difficulty in calculating shockwave's position and cross. For solving limitation of existing shockwave models, It develop new model with 2-regime linear model, New platoon model, Extended shockwave, etc. For verifying the validity of the proposed model, it was compared with delay of T7F and NETSIM by offset variation. In conclusion, it is thought that proposed model have outstanding performance to simulate traffic phenomenon.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.59 no.1
• /
• pp.44-54
• /
• 2023

In this study, the second-order Nomoto's nonlinear expansion model was implemented as a Tagaki-Sugeno fuzzy model based on the heading angular velocity to design the automatic steering system of a ship considering nonlinear elements. A Tagaki-Sugeno fuzzy PID controller was designed using the applied fuzzy membership functions from the Tagaki-Sugeno fuzzy model. The linear models and fuzzy membership functions of each operating point of a given nonlinear expansion model were simultaneously tuned using a genetic algorithm. It was confirmed that the implemented Tagaki-Sugeno fuzzy model could accurately describe the given nonlinear expansion model through the Zig-Zag experiment. The optimal parameters of the sub-PID controller for each operating point of the Tagaki-Sugeno fuzzy model were searched using a genetic algorithm. The evaluation function for searching the optimal parameters considered the route extension due to course deviation and the resistance component of the ship by steering. By adding a penalty function to the evaluation function, the performance of the automatic steering system of the ship could be evaluated to track the set course without overshooting when changing the course. It was confirmed that the sub-PID controller for each operating point followed the set course to minimize the evaluation function without overshoot when changing the course. The outputs of the tuned sub-PID controllers were combined in a weighted average method using the membership functions of the Tagaki-Sugeno fuzzy model. The proposed Tagaki-Sugeno fuzzy PID controller was applied to the second-order Nomoto's nonlinear expansion model. As a result of examining the transient response characteristics for the set course change, it was confirmed that the set course tracking was satisfactorily performed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.8B
• /
• pp.699-706
• /
• 2003

This paper is to verify that 2-state MMPP Model conform to ATM VBR traffic characteristics by measuring and analyzing real-time VBR traffic in KT's ATM network. As a result, we validated the fact that real-time VBR traffic of ATM network cannot be apply to MMPP model and must be represented by previously general On-Off Model with characteristics as follows: arrival rate of On state (λ$_1$) is deterministic, arrival rate of Off state (λ$_2$) is zero, and two transition rate (T$_1$,T$_2$) is only random variable. As research results are to handle real traffic, these results can be used to all ATM network traffic model with traffic management function such as KT's ATM network.

• The Journal of Fisheries Business Administration
• /
• v.37 no.2 s.71
• /
• pp.1-18
• /
• 2006

This study analyzes the effect of exchange rate and exchange risk on the import of Korea's fisheries. The estimation models consist of the following contents. The first model consists of one dependent variable-import quantity of fisheries$(IMQ_t^{Total})$ and three independent $variables-RP_t^{Total}$, $EX_t\;and\;EXV_t$. The second one-one dependent variable-import quantity of fisheries from China$(IMQ_t^{CN})$ and three independent $variables-RP_t^{CN},\;EX_t\;and\;EXV_t$. And the last one is made up of one dependent variable - import quantity of fisheries from $Japan(IMQ_t^{JP})$ and three independent $variables-RP_t^{CN},\;EX_t\;and\;EXV_t$. The estimation results show that all of the independent variables are statistically significant. Especially, the effect of Chinese $RP_t^{CN}$ is grater than Japanese $RP/P_t^{JP}$. However, the effect of Japanese $EX_t$ is grater than Chinese $EX_t$.

• Water for future
• /
• v.17 no.4
• /
• pp.281-291
• /
• 1984

In our Koreans river basins there are many of monthly rainfall data, but unfortrnately streamflow data needed are rare. Analysing monthly rainfall data of Somjin river basin, the stochastic theory model for calculation of monthly streamflow series of that region is determined. The model is composed of Box & Jenkins stansfer function plus ARIMA residual models. This linear stochastic differenced time series equation models can adapt themselves to the structure and variety of rainfall, streamflow data on the assumption of the stationary covarience. The fiexibility of Box-Jenkins method consists mainly in the iterative technique of building an AIRMA model from observations and by the use of autocorrelation functions. The best models for Somjin river basin belong to the general calss: $Y_t=($\omega$o-$\omega$_1B) C_iX_t+$\varepsilon$t$ $Y_t$ monthly streamflow, $X_t$ : monthly rainfall, $C_i$ :monthly run-off, $$\omega$o-$\omega$_1$ : transfer parameter, $$\varepsilon$_t$ : residual The streamflow series resulted from the proposed model is satisfactory comparing with the exsting streamflow data of Somjin gauging station site.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.10A
• /
• pp.796-806
• /
• 2009

This paper presents the method of emergency warning system operation based on T-DMB and the design of T-DMB AEAS receiver model. The proposed receiver model compares the geographical location of emergency with the location of DMB transmitting station from T-DMB broadcasting signal and classifies the receiver location into alert region, neighboring region and non-alert region and transmits the emergency alert message according to each region. The geographical location of emergency can be obtained from FIG 5/2 EWS data field for AEAS message and the location of DMB transmitting station can be estimated from either the latitude and the longitude in main identifier and sub identifier in FIG 0/22 data filed for TII(Transmitter Identification Information) or TII distribution database. In our experiment, we implemented the proposed receiver model with display section, storage section, DMB module for receiving broadcasting signal and control section and performed test emergency alert broadcasting using T-DMB signal generator.

• Journal of Korean Academy of Fundamentals of Nursing
• /
• v.3 no.1
• /
• pp.81-95
• /
• 1996

The purpose of this study was to investigate the effects of breast self-examination teaching methods which are printed material, videotape, demonstration used BSE model on women. The subjects for this study were non-medical professional 88 women in Kwangju. The data was collected from October 16 to November 24, 1995 by means of a structured questionnaire. For measuring BSE knowledge, Kim's(1994) instrument was used ard modified by researcher. For measuring BSE attitude based on health belief, Lee's(1982) & Kim's(1994) instrument was used and modified by researcher. Printed material from literature were reviewed by researcher, 'A woman's guide to breast self-examination' videotape by Nurse Practitioner Creation and BSE simulator by Narco were used 21 attitude scale and 13 knowledge scale were checked before and after teaching methods. The data was analyzed by frequency, paired t-test, ANOVA using the SAS program. The results were as follows : 1. The BSE total knowledge score after having teaching was higher than before, different significantly(t=-14.05, p=0.000). The most effective teaching method on BSE knowledge change was demonstration used BSE model in three teaching methods and was different significantly(F=8.44, p=0.000). 2. The BSE total attitude score after having teaching was changed to more positively, different significantly(t=4.59, p=0.000). The most effective teaching method on positive BSE attitude change was demonstration used BSE model in three teaching methods and was different significantly(F=3.21, p=0.045). 3. The HB score after having teaching was higher than before, and benefits, barriers and health concerns were different significantly(t=-2.51, p=0.014 ; t=-4.53, p=0.000 ; t=-3.71, p=0.000). Susceptibility and seriousness were not different significantly. 4. There were different significantly among knowledge, religion(F=3.92, p=0.013) and child (F=3.08, p=0.08). There were different significantly among attitude, age(F=4.65, p=0.05), mansturation state(F=4.39, p=0.016), and artificial abortion experience(F=5.18, p=0.026). There were different significantly among health concern, age(F=2.50, p=0.068), delivary experience(F=3.22, p=0.076), artificial abortion experience(F=5.46, p=0.023), and feeding(F=6.24, p=0.003). Printed material, videotape, and demonstration used BSE model may be valuable for changing positively knowledge and attitude related to BSE. Demonstration used BSE model was most effective teaching method in this study. Therefore, this study revealed that BSE teaching methods were a useful nursing intervention for promoting practice regularily and exactly on women.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.18 no.2
• /
• pp.151-156
• /
• 2008

This paper presents the stability analysis and design for a sampled-data fuzzy control system with neutral type of time delay, which is formed by a nonlinear plant and a sampled-data fuzzy controller connected in a closed loop. The sampling activity and neutral type of time delay will complicate the system dynamics and make the stability analysis much more difficult than that for a pure continuous-time fuzzy control system. Based on the fuzzy-model-based control approach, LMI(linear matrix inequality)-based stability conditions are derived to guarantee the nonlinear networked system stability. An application example will be given to show the merits and design a procedure of the proposed approach.