• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.393-396
• /
• 2008

Propellant consumption control for space launch vehicle can be achieved by propellant utilization system (PUS) and tank depletion system (TDS). In the course of developing new space launch vehicles, the main target of design is on reducing of space launch vehicle weight, which results in increasing both specific impulse and payload weight. The weights of space launch vehicles are generally allocated to structure, propulsion system, and propellants loaded. The quantity of propellants filled in propellant tanks may be estimated with the propellants actually consumed by propulsion system to complete its mission and the propellants left on-board at the time of engine shut-off. To minimize the remaining quantity of propellants on-board the supplying propellants' O/F ratio should be controlled from the certain time before engine shutdown. To control an O/F ratio, a control system, which accurately measures and compares the remainder of propellants in tanks and pipes, should be needed. This paper solely dedicates its contents to explore the merits and demerits of various level sensor, which is one of the important elements for PUS and TDS, and the transmission and control of signals within space launch vehicle.

• Journal of Korean Physical Therapy Science
• /
• v.19 no.1
• /
• pp.17-25
• /
• 2012

Purpose : The aim of this study was from data collection to item development in the first study before developing a valid and reliable instrument reflecting Korean's own language expression and culture. Methods : The fist survey was 140 osteoarthritis(OA) patients in 2 Cites was studied from November to December 2009. Open-ended questionnaire was decided 39 items from the first open survey. Questionnaire on the Korean Osteoarthritis Impact Measurement Scale(KAIMS) was recruited 2 professors and 5 physical therapists. Second survey was applied to 133 OA patients. Results : OA patients's average age${\pm}$standard deviation was $66.08{\pm}11.10$ years. The internal consistency reliability of 3 items. As estimated by Cronbach's alpha coefficient(${\alpha}$), was high(range, 0.86~0.96). 0.43~0.91 ${\alpha}$ coefficient for the internal consistency reliability of item-each scale was also high. However, item-discriminant validity on 3 items was low(${\alpha}$, 0.92~0.97). The construct validity by factor analysis was a little low. Conclusion : This study revealed that we confirmed a generation for 39 items on KAIMS reflecting Korean's own language expression and culture. Also, those of reliability were a little high. And, we will have to study the last instrument development (3rd study) by more subjects in the future.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.30 no.4 s.152
• /
• pp.542-553
• /
• 2006

The purpose of this study were to analyse of craniofacial shape by 3D and to develope of head models for Korean adults with gender and age groups. The 3D measurement technique adapted in this study was a novel approach compared that the same technique has been commonly used in measuring human bodies. The data and the model of head analysis can be used as a basic reference in developing various head related items such as hat, helmet, gas mask, ear phone, and etc. In this study, heads of 836 Korean adults were measured in 3D, analyzed by statistical methods, and modelized in 3D by gender and age groups. From the basic statistical data analysis, vertex-tragion and the length between the pupils were the longest in their twenties for both men and women, and grew shorter in elderly groups. In all categories, a significant difference appeared between men and women in their 20's, but the differences were less noticeable in elderly groups. Compared to the one size standard head model of the Korea Occupational Safety and Health Agency, the above three-dimensional standard head model would provide a more through fit because gender and age groups were sub-divided and analyzed in 3D.

• Journal of the Ergonomics Society of Korea
• /
• v.27 no.4
• /
• pp.95-101
• /
• 2008

This research is to develop PPG filtering method for respiration measurement in U-Health Care system. Respiration rate was determined by filtering PPG and analyzing its spectrum. Optimal filter of PPG has been selected to get respiration by testing 120 sets of experiment data using 700 filtering cases. As a result, 2nd order Bessel-filter that used band-pass cutoff frequency at 0.175~0.4Hz with second order was good at developing respiration signal. Respiration signal in time domain could be continuously analyzed by converting frequency domain using spectrum analysis. 24 seconds has been found to be optimal time duration of collecting PPG data for determining respiration. Therefore, this study was successful of getting not only heart activity but also respiration by only PPG. Minimal invasive measurement obtaining multi-bio information by one sensor can be expected to apply to U-Health Care and human computer interaction.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.572-582
• /
• 2017

It is definitely important to measure thrust during ground test when developing air-breathing engine, and in case of air-breathing engine, gross thrust should be calculated considering not only the measured thrust but also the force induced by the air flow of engine intake. Also, side thrust like yaw and pitch should be measured and analyzed using multi-component thrust measurement system. Engine performance was accurately evaluated by calculating the gross thrust of air breathing engine precisely which is analyzed from below serial procedure: labyrinth seal isolation, 1-axis gross thrust calculation, develop multi-component thrust measurement system, and side thrust analysis.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.4
• /
• pp.951-960
• /
• 2016

Tower insulators in electric power transmission network play a crucial role in preserving the reliability of the system. Electrical utilities frequently face the problem of flashover of insulators due to pollution deposition on their surface. Several research works based on leakage current (LC) measurement has been already carried out in developing diagnostic techniques for these insulators. Since the LC signal is highly intermittent in nature, estimation of pollution severity based on LC signal measurement over a short period of time will not produce accurate results. Reports on the measurement and analysis of LC signals over a long period of time is scanty. This paper attempts to use Random Forest (RF) classifier, which produces accurate results on large data bases, to analyze the pollution severity of high voltage tower insulators. Leakage current characteristics over a long period of time were measured in the laboratory on porcelain insulator. Pollution experiments were conducted at 11 kV AC voltage. Time domain analysis and wavelet transform technique were used to extract both basic features and histogram features of the LC signal. RF model was trained and tested with a variety of LC signals measured over a lengthy period of time and it is noticed that the proposed RF model based pollution severity classifier is efficient and will be helpful to electrical utilities for real time implementation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.11a
• /
• pp.384-387
• /
• 2003

In this paper, the evaluation of image quality was performed for digital radiography which is developing in using amorphous selenium as a photoconductor material for the purpose of offering basic research data and measurement technique about Medical Imaging Quality. So Modulation Transfer Function as a main factor of imaging quality evaluation was investigated by slit method. For measurement of MTF, Nuclear associates. 07-624 Slit camera image was obtained to study the variation of MTF corresponding to changing spatial frequency. And Presampling MTF was estimated by slit camera image with $10\;{\mu}m$ width at Digital Radiography. In this study, the obtained data demonstrates that the clinical value of a direct conversion type digital radiation detector using the amorphous selenium, which is being developed by domestic technology.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.205-208
• /
• 2005

Fabrication of large scaled mirror for the telescope application is the most challenging technology in recent year. Sophisticate technologies and know-how in fabrication and measurement are required to overcome the technological obstacles. KRISS(Korea Research Institute for Standards and Science) is now developing a large scaled mirror fabrication facility and KARI(Korea Aerospace Research Institute) is supporting the development. High precision interferometric test is required during the grinding and polishing of mirror to identify the surface profile precisely. The required fabrication accuracy of the mirror surface profile is $\lambda$/50 ms($\sim$10 nm for visible wave length). Thus the measurement accuracy should be far less than 10 m. To get this requirement, it is necessary to provide vibration free environment for the interferometer system and mirror under test. Thus the vibration responses on the mirror supporting table due to external vibration should be minimized by using a special isolation system. And the responses on the top of the tower, which hold the interferometer during test, should be minimized simultaneously. In this paper, we propose the concept design of vibration suppression system for the KRISS mirror fabrication facility.

• The Journal of Asian Finance, Economics and Business
• /
• v.8 no.5
• /
• pp.1139-1145
• /
• 2021

This study is aimed at developing a measurement instrument for the superior product development program of Deli Serdang cassava, Indonesia. This research population is the target population of Deli Serdang Micro, Small and Medium-sized Enterprises (MSMEs) which produces cassava. The sample was randomly selected and consisted of 300 MSMEs. The study method is research and development with confirmatory factor analysis using Amos software. The data collection technique was a questionnaire. Study results used the maximum likelihood method which showed that the validity and reliability instruments met the ideal loading factor value > 0.5 and a significance value of p (0.000). The model built also meets the fit criteria based on the Goodness of Fit Model Standard. All instruments are presented to build and measure the superior cassava product development program by Deli Serdang MSMEs. This superior product development program comprises (1) economic contribution (with a loading factor value of 0.76) (2) social aspects (with a loading factor value of 0.76) (3) cultural aspects (with a loading factor value of 0.99) and (4) institutional (with a loading factor value of 0.87). This result means that all instruments have proven construct validity.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.37 no.2
• /
• pp.81-89
• /
• 2019

As the need for the integration of administrative datasets and address information increases, there is also growing interest in POI (Point of Interest) data as a source of location information across applications and platforms. The purpose of this study is to develop an alias database management method for efficient POI searching, based on POI data representing position. First, we determine the attributes of POI alias data as it is used variously by individual users. When classifying aliases of POIs, we excluded POIs in which the typo and names are all in English alphabet. The attributes of POI aliases are classified into four categories, and each category is reclassified into three classes according to the strength of the attributes. We then define the quality of POI aliases classified in this study through experiments. Based on the four attributes of POI defined in this study, we developed a method of managing one POI alias through and integrated method composed of word embedding and a similarity measurement. Experimental results of the proposed POI alias management method show that it is possible to utilize the algorithm developed in this study if there are small numbers of aliases in each POI with appropriate POI attributes defined in this study.