• Journal of the Ergonomics Society of Korea
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• v.35 no.5
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• pp.319-341
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• 2016

Objective:This research analyzed the lower-limb motion in kinetic and kinematic way while walking on various terrains to develop Foot-Ground Contact Detection (FGCD) algorithm using the Inertial Measurement Unit (IMU). Background: To estimate the location of human in GPS-denied environments, it is well known that the lower-limb kinematics based on IMU sensors, and pressure insoles are very useful. IMU is mainly used to solve the lower-limb kinematics, and pressure insole are mainly used to detect the foot-ground contacts in stance phase. However, the use of multiple sensors are not desirable in most cases. Therefore, only IMU based FGCD can be an efficient method. Method: Orientation and acceleration of lower-limb of 10 participants were measured using IMU while walking on flat ground, ascending and descending slope and stairs. And the inertial information showing significant changes at the Heel strike (HS), Full contact (FC), Heel off (HO) and Toe off (TO) was analyzed. Results: The results confirm that pitch angle, rate of pitch angle of foot and shank, and acceleration in x, z directions of the foot are useful in detecting the four different contacts in five different walking terrain. Conclusion: IMU based FGCD Algorithm considering all walking terrain possible in daily life was successfully developed based on all IMU output signals showing significant changes at the four steps of stance phase. Application: The information of the contact between foot and ground can be used for solving lower-limb kinematics to estimating an individual's location and walking speed.

• Journal of KSNVE
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• v.9 no.1
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• pp.85-96
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• 1999

For ASME Code pumps in nuclear power plants, inservice test is required to assess the operational readiness in accordance with ASME code and related regulations. The objective of this study therefore, is to develop the technical background of the degradation of pump performances and conditions due to low flow rate operation. In addition. the detection techniques of pump operating conditions are to be developed to enhance the safety and economy of nuclear power plants. A test loop consisted of pump, motor. water tank, flow rate measurements and piping system with flow control devices was established for this study. Two typical pumps, 1-stage volute pump and 3-stage turbine pump, were selected and the test was performed upon two major point of views ; i.e., pump discharge pressure pulsations analysis and pump vibration spectrum analysis. From the test results, it is concluded that (1) the pump vibration affected by the natural frequency of operating pump is significant in the low frequency zone (around 1 Hz) : the vibration amplitude. especially. is an important factor during low flow rate operation. and shall be monitored to ensure that it is within the limit of ASME OM code Part 6, (2) the vibration frequency and pump discharge pressure are affected by vane pass frequency and running speed, (3) the wave phenomena due to the compressiblity of water is anticipated during low flow rate operation. and the pump system shall be designed to prevent it and. finally, (4) the technical background of the degradation of pump performances and conditions due to low flow rate operation is provided.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.31-36
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• 2000

High temperature and pressure materials in power plant are degraded by creep damage, if they are exposed to constant loads for long times, which occurs in the load bearing structures of pressurized components operating at elevated temperatures. Many conventional measurement techniques such as replica method, electric resistance method, and hardness test method for measuring creep damage have been used. So far, the replica method is mainly used for the Inspection of High temperature and pressure components. This technique is, however, restricted to applications at the surface of the testpieces and cannot be used to material inside. In this paper, ultrasonic evaluation for the detection of creep damage in the form of cavaties on grain boundaries or integranular microcracks are carried out. And the absolute measuring method of quantitative ultrasonic velocity technique for Cr-Mo material degradation is analyzed. As a result of ultrasonic tests for crept specimens, we find that the sound velocity is decreased as the increase of creep life fraction$({\Phi}_c)$ and also, confirmed that hardness is decreased as the increase of creep life fraction$({\Phi}_c)$ but the coefficient of ultrasonic attenuation is increased as the increase of creep life fraction$({\Phi}_c)$. Finally based on the result in this paper, it can be recognized that the ultrasonic techniques using velocities and attenuation coefficient factor are very useful non-destructive methods to evaluate the degree of material degradation in fossile power plants.

• Journal of Korean Neurosurgical Society
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• v.46 no.4
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• pp.355-359
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• 2009

Objective : The definition of empty sella syndrome is 'an anatomical entity in which the pituitary fossa is partially or completely filled with cerebrospinal fluid, while the pituitary gland is compressed against the posterior rim of the fossa'. Reports of this entities relating to the brain tumors not situated in the pituitary fossa, have rarely been reported. Methods : In order to analyze the incidence and relationship of empty sella in patients having brain tumors, the authors reviewed preoperative magnetic resonance imaging (MRI) of 72 patients with brain tumor regardless of pathology except the pituitary tumors. The patients were operated in single institute by one surgeon. There were 25 males and 47 females and mean patient age was 53 years old (range from 5 years to 84 years). Tumor volume was ranged from 2 cc to 238 cc. Results : The overall incidence of empty sella was positive in 57/72 cases (79.2%). Sorted by the pathology, empty sella was highest in meningioma (88.9%, p=0.042). The empty sella was correlated with patient's increasing age (p=0.003) and increasing tumor volume (p=0.016). Conclusion : Careful review of brain MRI with periodic follow up is necessary for the detection of secondary empty sella in patients with brain tumors. In patients with confirmed empty sella, follow up is mandatory for the management of hypopituitarism, cerebrospinal fluid (CSF) rhinorrhea, visual disturbance and increased intracranial pressure.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.6
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• pp.1673-1675
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• 2005

The pulse diagnosis is an important and universal method in Oriental medicine. Nevertheless, because of characteristic that depends on subjective sense of Oriental medicine doctor (OMD), it is not recognized by objective basis. The Korean Institute of Oriental Medicine(KIOM) and Daeyo Medi. Co. Ltd. developed the 3-D Mac using arrey piezoresistive sensors and multi-axial robot. 133 healthy subjects participated in this study, 75 males and 58 females, between 20 and 70 years of age. All subjects were relaxed in a supine position on a comfortable chair for twenty minutes before the measurement was taken. The measured position is the radial artery of subject's left wrist and the position is called Chon, Kwan and Chuck in Oriental medicine. To detect floating and sinking pulse, we established coefficient of floating and sinking(CFS). CFS means relative position of maximum pulse pressure in PH curve. The lower CFS value means that the pulse has floating tendency. There was significant diffence between CFS and diagnosis of floating-sinking pulse by OMD(p=0.020). CFS value of over 40's group was significantly larger than those of 20's and 30's(p=0.000). There was no significant difference between male and female(p=0.061).

• Journal of Korean Society of Water and Wastewater
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• v.31 no.5
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• pp.459-469
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• 2017

A real scale leakage test facility was developed to study the leak signal characteristics of water supply pipelines, and then leak tests were carried out. The facility was designed to overcome the limited experimental circumstances of domestic water supply pipeline experimental facilities. The length of the pipeline, which was installed as a straight line, is 280m. Six pipes were installed on a 70m interval with different pipe material and diameters that are DCIP(D200, D150, D100, D80), PE(D75) and PVC(D75).The intensity of the leakage is adjusted by changing the size of the leak hole and the opening rate of ball valve. Various pressure conditions were simulated using a pressure reducing valve.To minimize external noise sources which, deteriorate the quality of measured leak signal, the facility was built at a quiet area, where traffic and water consumption by customers is relatively rare. In addition, the usage of electric equipment was minimized to block out noise and the facility was operated using manual mode. From the experimental results of measured leakage signal at the facility, it was found that the signal intensity weakened and the signal of high frequency band attenuated as the distance from the water leakage point increased.

• 대한공업교육학회지
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• v.31 no.1
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• pp.185-199
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• 2006

In this paper, to detect lateral direction sound pressure fiber optic sensor using Fabry-Perot interferometeric sensor array was fabricated and experimented. This parallel sensor array composed of one light source and the light split into each sensor using directional coupler and to see the output signal the array system do not need any digital signal processor. As a lateral direction sound source arbitrary sound frequency of 100Hz, 200Hz, and 655Hz using by nondirectional speaker were applied to the array sensor which installed on $60cm{\times}60cm{\times}60cm$ latticed structure. The detected signals from the two sensors were analyzed in the time and frequency domains. It was confirmed that the suggested sensor array detected applied sound source well but there were a little amplitude differences in between the sensors. Because the sensor supported simply at both ends theoretical analysis was performed and its solution was suggested. To compare the theoretical and experimental results arbitrary sound frequency of 2kHz was applied to the sensor array. It shows that experimental results was good agreement with theoretical results.

• The Journal of Korean Obstetrics and Gynecology
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• v.31 no.1
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• pp.57-83
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• 2018

Purpose: This research has been carried out to find out correlation between test results of ABR-2000 and other diagnostic equipments to enhance significance of accurate diagnosis and clinical usage of ABR-2000. Methods: Duration of the 31 months from December 2012 to June 2015, records of 564 outpatients at gynecology department have been selected. The 564 patients were tested, using all 3 different test equipments of ABR-2000, DSOM, and 3D Blood Pressure Pulse Analyzer (3D-MAC) without test errors or mis-recordings. Correlation between 3D Blood pressure Pulse Analyzer, DSOM and ABR-2000 were analyzed by frequency & ratio factor of statistic data records of patients groups devided by 8 different disease symptom and by comparison of the groups in the form of Regulation and Graph presented on ABR-2000 equipment. Results: 1. The indicator L in all 1, 2, and 3 quadrant in the graph means the activity and reactivity of the upper body biodynamics detection rate is low and which result is very common symptom among gynecological patients. 2. The portion of patients with hypermenorrhea, endometritis, and menstrual pain symptom among the indicator L group in the reactivity 1-3 quadrantin is significantly high. 3. When 3D Mac analyzer indicates H, diastole decreases while systole increases and tachycardia increases then the blood circulation is expected to increase. In case of indication L, diastole increases and systole decreases then, the blood circulation is expected to decrease.

• Journal of the Korea Society of Computer and Information
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• v.8 no.3
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• pp.179-187
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• 2003

This study investigate the reasons of organizational failure in detection and appropriate response to risk signal. The Crisis does not come true suddenly, there is some risk signals in crisis. If Organization detect the risk signals the crisis is come true opportunities, if not the crisis is come true disastrous outcome. This is use the system dynamics approach. System Dynamics assume the system as a collection of causal feedback loop, so we understand the dynamics around the problems. This investigate suggest that, the focus on growth is the a kind of promotional pressure and the pressure drive the organization to less attention the risk signal, so the risk is underestimate In proportion to real risk. Ultimate, the organization entrap the promotional climate and insensible to security. This study is a kind of hypothesis-discovering research, in the further study, the discovered hypothesis will be empirically tested.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.6
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• pp.767-773
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• 2017

Infrared stealth is an important technology for naval ships. This technology helps improve the anti-detection performance and survivability of naval ships. In general, the infrared signature of naval ships are categorized into internal and external heat source. External signature are generated by ship surface heating by solar flux as well as the complicated heat transfer process with the surrounding weather condition. Modern naval ships are equipped with seawater injection nozzles on the outside for nuclear, biological and, chemical, and these nozzles are used to control external signature. Wide nozzle placement intervals and insufficient injection pressure, however, have reduced seawater dispersion area. To address this problem, nozzle installation standards must be established. In this study, an actual-scale experimental system was implemented to provide the evidence for nozzle installation standards in order to reduce the infrared signature of naval ships. In addition, the environmental conditions of the experiment were set up through computational fluid dynamics considering the ocean climate data and naval ship management conditions of South Korea. The dispersion distance was measured using a high-resolution thermography system. The flow rate, pipe pressure, and dispersion distance were analyzed, and the evidence for the installation of seawater injection nozzles and operation performance standards was suggested.