• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.2
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• pp.193-201
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• 2014

This study provided safe sailing speed and appropriate passing time to areas of known strong current water to prevent marine accident of the ships. To the interpretation of these data which target Myeongnyang waterway, AIS data of the ship was collected from $12^{th}$ July to $15^{th}$ July 2010 and site environment was investigated on $4^{th}$ September 2010. On the basis of the collected data, the 'Minimum Navigation Speed' and 'Optimum Navigation Speed' were calculated. It has also considered the 'Spare control force' or allowance and the 'Respond Rudder Angle' for each tidal current speed. Additionally, it suggested the safe passing time to strong current area by analyzing tidal level and tidal current speed. The conclusion of the research are as follows : (1) If the flow rate is greater than 4.4 kn, it is difficult for the model ship to control herself by her own steering power and to cope with tidal current pressure force and yaw moment caused by the tidal current.. (2) The minimum navigation speed should be over 2.3 times the tidal current and the optimum navigation speed should be over 4.0 times the tidal current. (3) When spring tide, the optimum passing time at Myeongnyang waterway is between 30 minutes to 1 hour before the time of high/low water, and at 5 hours after high/low water, passing of ships should be avoided because it is time when the flow rate is over 4 kn.

• Korean Journal of Applied Biomechanics
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• v.25 no.4
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• pp.431-440
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• 2015

Objective : The purpose of this study was to investigate the relations between accuracy score and the motions which are performed in PyeongWon Poomsae, thereby developing objectivity in accuracy evaluations for Poomsae competitions. Method : The subjects were six male Poomsae players (age: $21.2{\pm}1.17yrs$, height: $173.4{\pm}3.95cm$, weight: $67.7{\pm}7.65kg$). A three-dimensional motion analysis was performed on the subjects using six high-speed cameras (60 frames/sec) and subjects' performed motions were evaluated by 5 evaluators. The entire Pyeong Poomsae was divided into 13 events and 9 phases; there were three pairs of symmetric phases among them: front kick & turning side kick phases (3PH, 3-1PH), arm motion & stance phases (4PH, 4-1PH), side kick with Hakdari-stance phases (5PH, 5-1PH). Performance time, change and range of COM, height of vertex, and foot of side kicks were analysed. The Data was analysed utilizing correlation analysis. Results : There was a positive correlation between accuracy score and the difference between right and left range of COM (X direction) at 4PH (r=0.921, p=0.009). Conclusion : The results of our study indicate that it is necessary to consider some of objective criterion such as performance time, COM range, and symmetrical movements in accuracy evaluations of Poomsae competitions.

• Journal of Korean Society of Transportation
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• v.26 no.1
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• pp.145-153
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• 2008

Existing shortest-path algorithms mainly consider a single attribute. But traveler actually chooses a route considering not single attribute but various attributes which are synthesized travel time, route length, personal preference, etc. Therefore, to search the optimal path, these attributes are considered synthetically. In this study route searching algorithm which selects the maximum utility route using discrete choice model has developed in order to consider various attributes. Six elements which affect route choice are chosen for the route choice model and parameters of the models are estimated using survey data. A multinomial logit models are developed to design the function of route choice model. As a result, the model which has route length, delay time, the number of turning as parameter is selected based on the significance test. We use existing shortest path algorithm, which can reflect urban transportation network such as u-turn or p-turn, and apply it to the real network.

• Journal of Biosystems Engineering
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• v.34 no.6
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• pp.404-410
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• 2009

This study was carried out to develop a self-propelled type explosive subsoiler for improving the root zone soil conditions in orchard and other forest fields. Prototype was designed to be able to inject air and other soil improving material such as lime into soil at the same time, and thus improve the air permeability and drainage of orchard soils to promote the root growth of tree for high quality fruit production. Soil penetration device of explosive subsoiler is composed of air hammer, penetration rob and air injection nozzle. To support the soil penetration device of explosive subsoiler to penetrate vertically, modified Scott-Russel mechanism was used. Timing control device for simultaneous injection of soil improving material with air was attached to the out side wall of air cylinder and as the cylinder move, the soil improving material was injected into soil at the same time. Turning radius of prototype was 2.2-2.3 m with good mobility in sloped land. It took approximately 1 minute for lime injection system to reach the optimum pressure of 9.9 kg/$cm^2$, average 10-20 seconds were required to rupture soil with the depth of 50 cm and 2-3 seconds were required for explosion, so all in all about 1 minute and 20 seconds were required for one cycle of explosion. Maximum soil rupture depth and diameter were 50 cm and 3-4 m respectively depending on the soil type and soil moisture content. For final design of explosive subsoiler inclination angle of lime hopper was increased from 60 degree to 70 degree and the shape of hopper was changed from rectangular cone to circular cone to solve the clogging problem of lime at out let. Agitating system operated by compressed air was attached to the metering device of the prototype, thus more than 90 cc of lime was discharged per cycle from metering device without clogging problems.

• Women's Health Nursing
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• v.3 no.1
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• pp.82-92
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• 1997

The purpose of this study was attempted to understand the substance and meaning of menopause experienced by women through informal interviews with oral consent. The informants were 6 perimenopausal women of 50-55 years old who are executing menopause. Colaizz's analytical method, a type of phenomenological analysis, was used to analyze data recorded by audiotape. One professor and a master's degree student who understand phenomenology, and the one who has a master of arts examined the validity between the meanings composed of the clusters of themes. Findings were turned out to be valid through validation process as the last step. The meaning of menopause implied both 'concept about menopause' and 'menopause as a time of change'. Menopause was mostly considered as cessation of menstruation as a physiological, natural, and normal process by aging. However, some people regarded menopause as a loss of youth and womanhood and lessening of every function of the body. Menopause as the time of changes means 'the period of' 'hormonal changes' such as change of menstruation, hot flushes, perspiration, and palpitation ; 'body function changes' of visual acuity, physical strength, sleeping, digestion, thoughts, bone and joints, skin sensibility, sexual pattern and intelligence ; 'emotional changes' such as anxiety, loneliness, gloominess, and nervousness. Menopause is a turning point on the women's life cycle accompanying various kind of changes and health problems. Therefore it is inevitable to develop strategy helping menopausal women pass through the critical successfully by adapting and coping with their critical period toward the healthy and better quality of life individually rather than putting them all into the standardized hormonal replacement protocol.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.1
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• pp.178-203
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• 2018

In this paper, authors have been evaluated the Frame Error Rate (FER) performance of IEEE 802.11 a/g/p standard 5 GHz frequency band WLAN over Rayleigh and Rician distributed fading channels in presence of Additive White Gaussian Noise (AWGN). Orthogonal Frequency Division Multiplexing (OFDM) based transceiver is implemented by using real-time signal processing frameworks (IEEE 802.11 Blocks) in GNU Radio Companion (GRC) and Ettus USRP N200 is used to process the symbol over the wireless radio channel. The FER is calculated for each sub-carrier conventional modulation schemes used by OFDM such as BPSK, QPSK, 16, 64-QAM with different punctuated coding rates. More precise SNR is computed by modifying the SNR calculation process of YANS and NIST error rate model to estimate more accurate FER. Here, real-time signal constellations, OFDM signal spectrums etc. are also observed to find the effect of multipath propagation of signals through flat and frequency selective fading channels. To reduce the error rate due to the multipath fading effect and Doppler shifting, channel estimation (CE) and equalization techniques such as Least Square (LS) and training based adaptive Least Mean Square (LMS) algorithm are applied in the receiver. The simulation work is practically verified at GRC by turning into a pair of Software Define Radio (SDR) as a simultaneous transceiver.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.16 no.1
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• pp.37-42
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• 1980

The purpose of the present study is to find the color induced maximum gathering rate and to observed'the trend of the - gathering rate by using two species of commercial fishes: rock bream, Oplegnathus fasciatus (Temminet et Schlegel) and 'grass puffer, Fugu niphobles (Jordan et Snyder). An experimental tank($360L{\times}50W{\times}55H cm$) was set up in a dark room. An illumination system was attached to the two end of tank to fix horizontal light intensity by co~bination c' one light bulb(20W) and four filters (red, blue, yellow, white) and the five regulating filters in order to fix light intensity. During the experiment water depth was maintained 50 cm lever in the tank. The tank was marked into six longitudinal sections each being 60 em long to observe the distribution of fish. The fish were acclimatized in dark condition for 40 minutes prior to the main experiment. Upon turning on the light, the number of fish in each section was counted 40 times every 30 seconds, and the gathering rates ,were obtain from the average number of fish in each secion. The color induced maximum gathering rate of rock bream appeared to be red, blue yellow and white color orderly.However, that of grass puffer appeared to be blue, white, yellow and red color orderly. Trend of the gathering rate in illumination time showed the remarkable fluctuation in the rock bream and little difference at the two color light sources. However, trend of the gathering rate in illumination time showed the little fluctuation in grass puffer and much difference at the two color light sources.

• Journal of the Ergonomics Society of Korea
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• v.30 no.1
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• pp.213-220
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• 2011

Objective: The aim of this study was to investigate middle-aged drivers' driving performance and heart-rate as the behavior and physiological changes due to intersection types in left-turn situation. Background: In Korea, the drivers were aged 40~50s are most plentiful. In addition, the intersection traffic accidents are increasing every year. However, the researches for middle-aged drivers and intersection environments have been little. Method: In this study, three kinds of left-turning intersection types(T1, T2, T3) was used as the within-subject independent variables, three age groups(young, middle-aged, elderly) was used as the between-subject independent variables. Also, passing time, approaching velocity, speed and steering variations and heart-rate were used as dependent variables. Results: Overall, middle-aged drivers' driving behaviors were similar to those of the younger drivers. At the T2 intersection type, however, the approaching velocity of middle-aged drivers was similar to younger drivers, whereas the passing time of middle-aged drivers was similar to elderly drivers. Conclusion: These results could be interpreted that a transition driving behavior of middle-aged drivers in terms of age would be appeared on the T2 intersection type. Application: The results might help to understand the characteristics of driving behavior for middle-aged drivers.

• Journal of Advanced Navigation Technology
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• v.19 no.5
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• pp.458-463
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• 2015

This paper suggests detection system for the movement of patient on bed based on IEEE802.15.4 by using pressure pad and guard sensor. The system is designed to detect ordinary activities of patients on bed as well as patients' falling from the bed while sleeping at night. The node that is installed at bed sends data to gather when the pressure pad and sensor of guard detect patients' activities and falling. These data sent to gather are transmitted to monitor at help desk by TCP/IP communication. To remove unnecessary data that occurred due to switch chattering during tossing and turning, timer of MCU is used. Also, Communication module can change transmission power to apply this system to various environments of hospital room. Therefore, the nurse can take care of patients on bed in real time with data about patients' conditions.

• Journal of the Korea Society of Computer and Information
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• v.23 no.3
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• pp.101-106
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• 2018

The purpose of this study is to analyze the patterns of unconsciousness smartphone use by using an app and a self-administered survey on smartphone addiction comparatively and examine differences between recognition and behavior about actual smartphone use and examine how smartphone addiction influences learning. With an app installed in smartphones, this author collected and analyzed data about users' unconsciousness using patterns for a month. According to the results, there were significant differences found in users' recognition and actual time for use and also frequency of turning on the display. Also, 22% of the subjects used their smartphone over 8 hours a day, and 76% more than 5 hours. Over 95% turned on the display more than 100 times a day, and in extreme cases, they did more than 300 times. In the meantime, users not only in the smartphone addiction high risk group and the potential risk group but also in the general user group are found to use their smartphone too long and too much and frequently turn on the display. The apps that the general user group is mainly using are entertaining apps, and their school records are rather good, so excessive use does not always lead to addiction or learning disorder. Therefore, if we develop more diverse contents for learning and provide digital literacy education, smartphone use will bring more positive effects instead. In follow-up research, the app should be corrected to collect more accurate information, and as variables in personal areas, this researcher will also measure depression, anxiety, stress, self-esteem, and emotional control, and so on to see how they are associated with smartphone use.