• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.11a
• /
• pp.477-482
• /
• 2009

Though rocket nozzle flow is very important to the rocket performance, the direct measurement is very difficult because of high temperature and high pressure gas flow. Then the experiment utilizing the hydraulic analogy has been developed for such a problem. Supersonic flows through an axisymmetric De Laval nozzle of solid rocket motor was simulated in a 2-D sluice-type water-table designed and manufactured utilizing hydraulic analogy. Methods to minimize or account for non-analogous effects in the hydraulic system must be reviewed for the quantitative application of the hydraulic analogy. In this application the water table is inclined slightly, so that gravity acceleration has a small component in the direction of motion, thus compensating for the effect of friction. Flow visualization leads to better understanding of the analogous system. Within the experimental errors, it is shown that the hydraulic analogy can be used as an effective tool for the study of two dimensional isentropic flows of gases in many fields.

• Journal of Korean society of Dental Hygiene
• /
• v.18 no.5
• /
• pp.853-862
• /
• 2018

Objectives: This study involved a non-equivalent control group, pre-test/post-test measurement experiment to evaluate the efficacy of distributing plaque disclosing agents to healthy adults living in South Korea and promoting its self-application. Methods: O'Leary index, PHP index, oral health behavior intention, and oral care satisfaction were used as research tools. A notice was posted on the bulletin board from September 12 to October 15, 2016, to recruit adults aged 20-50 years. Data were analyzed using SPSS Version 22.0, and frequency analysis, Pearson's chi-squared, one-way analysis of variance (ANOVA), Kruskal-Wallis, and repeated measures ANOVA were performed. Results: The O'Leary index was significantly reduced in the group (p<0.01), and time (p<0.01) after education and width of the decrease had the highest score in the group that received education on plaque disclosing only. They were followed by the group that received education on plaque disclosing and the rolling method, the group that received education on the rolling method alone, and the control group. The PHP index significantly decreased in the group(p<0.01) and time (p<0.01), and the group time (p=0.039) after education, and width of the decrease had the highest score in the group that received education on plaque disclosing and rolling method. They were followed by the group that received education on plaque disclosing alone, the group that received education on the rolling method alone, and the control group. Conclusions: Based on the aforementioned findings, the direct use of plaque disclosing had a marked effect on self-oral care. These results suggest that the self-application of plaque disclosing could be an effective self-care method for improving the oral environment.

• The Journal of Churna Manual Medicine for Spine and Nerves
• /
• v.16 no.2
• /
• pp.97-105
• /
• 2021

Objectives This study is aimed to evaluate cost-effectiveness of treatment of Korean Medicine for whiplash associated disorders (WAD) and to suggest the direction of future research. Methods We searched papers in Pubmed database to use some keywords indicating whiplash injury syndrome, treatment of Korean Medicine and cost-effectiveness. After searching, appropriate papers were selected depending on the exclusion criteria. The selected papers were analyzed in the sections of author, publication year, intervention and control groups, outcome measurement, the list including in the cost, cost-effectiveness, cost-utility and study design. Results Four studies about effect of Korean medicine and 3 studies about economic evaluation were finally included. Acupuncture was effective for balance disorder and neck pain. Economic evaluation studies used analytical decision model or cost-consequence analysis. Cost-effectiveness analysis using visual analog scale and cost-utility analysis using quality adjusted life years were performed. Initiating timing of proper management affected the consequence of treatments. Direct and indirect medical costs including supportive devices, and non-medical costs such as litigation were considered. Conclusions We conclude that studies haven't been conducted so far to evaluate the cost-effectiveness of Korean Medicine in whiplash injury syndrome. Thus, future studies are needed in this section.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.10
• /
• pp.154-160
• /
• 1996

The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. The limitation of this control scheme is that the feedback signal does not account for additional dynamics of the tool post and the material removal process. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surfice. However, as the accuracy requirement gets tighter and desired surface cnotours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining process prohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normal to the face of the workpiece can be filtered through an appropriate admittance transfer function to result in the estimated dapth of cut. This can be compared to the desired depth of cut to generate the adjustment control action in additn to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. The recursive least-squares algorithm with forgetting factor is proposed to identify the parameters and update the cutting process in real time. The normal cutting forces are measured to identify the cutting dynamics in the real diamond turning process using the precision dynamoneter. Based on the parameter estimation of cutting dynamics and the admitance model-based nanodynamic control scheme, simulation results are shown.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.3
• /
• pp.221-228
• /
• 2013

An experimental study was carried out to investigate the effects of the injection timing on the spray and combustion characteristics in a spray-guided direct-injection spark-ignition (DISI) engine under lean stratified operation. An in-cylinder pressure analysis, exhaust emissions measurement, and visualization of the spray and combustion were employed in this study. The combustion in a stratified DISI engine was found to have both lean premixed and diffusion controlled flame combustion characteristics. The injection timing condition corresponding to the stratified mixture characteristics was verified to be a dominant factor for these flame characteristics. For the early injection timing, a non-luminous blue flame and low combustion efficiency were observed as a result of the lean homogeneous mixture formation. On the other hand, a luminous sooting flame was shown at the late injection timing because of an under-mixed mixture formation. In addition, the smoke emission and incomplete combustion products were increased at the late injection timing as a result of the increased locally rich area. On the other hand, the NOx emissions decreased and IMEP increased as the injection timing retarded. The combustion phasing produced by the injection timing was verified as the reason for this observation.

• Journal of Hospice and Palliative Care
• /
• v.16 no.3
• /
• pp.145-154
• /
• 2013

This study was performed to evaluate the existing pain assessment methods including the tools developed for use with nonverbal older adults with dementia, and to suggest recommendations to clinicians based on the evaluations. Computerized literature searches published after year 2000 using databases - Google scholar, RISS, KoreaMed, Medline, ScienceDirect, CINAHL - were done. Searching keywords were 'pain', 'pain assessment', and 'cognitive impairment/dementia'. The pain assessments for non-communicative dementia patients who are unable to self-report their pains are often made using the assessment tools relying on the observation of behavioral indicators or alternatively the strategy of surrogate reporting. While several tools in English version and only one in Korean are suggested for the pain assessments based on the observation of behavioral indicators, none are commonly used. In this review, we selectively evaluated those tools known to show relatively higher degree of validity and reliability for nonverbal older adults with dementia, namely, CNPI, DOLOPLUS 2, PACSLAC, PAINAD, and DS-DAT. It is hoped that the present review of selected tools for assessing pain in those vulnerable population and the general recommendations given be useful for clinicians in their palliative care practice. And future studies should focus on enriching the validation of the useful tools used to observe the nonverbal patient's behavioral indicators for pain in Korean.

• Geophysics and Geophysical Exploration
• /
• v.11 no.1
• /
• pp.15-25
• /
• 2008

Ocean-bottom seismometer (OBS) positions are one of the key parameters in an OBS-airgun seismic survey for crustal structure study. To improve the quality of these parameters, we have developed a new method of determining OBS positions, using airgun shot data and bathymetric data in addition to available distance measurements by acoustic transponders. The traveltimes of direct water waves emitted by airgun shots and recorded by OBSs are used as important information for determining OBS locations, in cases where there are few acoustic transponder data (<3 sites). The new method consists of two steps. A global search is performed as the first step, to find nodes of the bathymetric grid that are the closest to explaining the observed direct water-wave traveltimes from airgun shots, and acoustic ranging using a transponder system. The use of precise 2D bathymetric data is most important if the bottom topography near the OBS is extremely rough. The locations of the nodes obtained by the first step are used as initial values for the second step, to avoid falling into local convergence minima. In the second step, a non-linear inverse method is executed. If the OBS internal clock shows large drift, a secondary correction for the OBS internal clock is obtained, as well as the OBS location, as final results by this method. We discuss the error and the influence of each measurement used in the determination of OBS location.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.18 no.1
• /
• pp.1-15
• /
• 2016

Annual litterfall production and leaf area index (LAI, $m^2/m^2$) were estimated using litter traps in Gwangneung, Mt. Taewha and Mt. Gariwang. Annual total litter fall production including branch, bark, others was the highest in Gwangneung($7497.3{\pm}326.5kg/ha/yr$), which had the highest basal area at late successional stage, and followed by Mt. Taewha($5929.1{\pm}225.8kg/ha/yr$) and Mt. Gariwang($3,210.1{\pm}220.1kg/ha/yr$). Mt. Gariwang had the lowest litterfall production due to high elevation and short growing season even with the higher stand density and basal area than Mt. Taewha. Similarly, LAI, which was calculated by multiplying the mass of leaf litter with specific leaf area, was the highest in Gwangneung($5.99{\pm}0.69$) and followed by Mt. Taewha($5.20{\pm}0.24$) and Mt. Gariwang($4.06{\pm}0.42$) and the upper canopy species had the highest leaf area index in every sites (Gwangneung : 4.72, Mt. Taewha : 3.08, Mt. Gariwang : 2.19). However, species specific LAI estimation based on the relationship between basal area and leaf area was limited due to upper canopy species non-proportionality of basal area with LAI. In addition, the comparison between direct and indirect LAI measurement showed the importance of canopy clumping, especially at high density. Our study emphasized the necessity of direct LAI measurement using litter fall traps especially at temperate deciduous forest with diverse species.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.12
• /
• pp.124-133
• /
• 2015

Electro interstitial scan shows potential as a non-invasive screening method. It can discriminate some diseases based on electric current response to induce low intensity direct current to limbs or local area of body. DDFAO was invented in France and it is claimed that multi-channel EIS(Electro Interstitial Scan) is useful for various diseases, especially, diagnoses of endocrine system such as diabetics are very effective. In this study, we verified the repeatability and sensitivity of DDFAO by using a RC phantom model and its clinical usefulness using data obtained from normal and diabetes subject groups. As a result, it showed the repeatability and the output change according to change of phantom characteristic, but it was hard to distinguish normal and patient groups non-invasively with just six surface electrodes of DDFAO. The repeatability and the clinical accuracy was not sufficient for screening or diagnostic purposes, as well. In spite of the results with low repeatability and accuracy conducted in this study, we still need further investigations to improve the EIS-based measurement method; EIS is very convenient and simple and it shows potential as a screening tool of the whole body health conditions rather than localized disease diagnosis.

• Parasites, Hosts and Diseases
• /
• v.28 no.1
• /
• pp.25-30
• /
• 1990

The direct wet mount examination of vaginal. secretion, widely applied for the diagnosis of Trichcmonas vaginalis infection in woman patients, is rapi4 and economical, however, the sensitivity of this technique is not so high. In this study enzyme-linked immunosorbent assay (ELISA) was employed for the detection of serum anti-T. vaginalis IgG and IsM antibodies from 30 vaginal trichomoniasis patients and 30 non-infected healthy persons. The results were as follows: 1. Serum ELISA-IgG value was $0.37{\pm}0.134(Mean{\pm}S.D.)$ in vaginal trichomoniasis patients and $0.21{\pm}0.054$ in healthy controls(P<0.005), and the sensitivity and specificity of ELISA for serum IgG antibody were 70.0% and 96.7%, respectively. 2. Serum ELISA-IgM value was $0.33{\pm}0.177 (Mean{\pm}S.D.)$ in vaginal trichomonlasls patients and $0.11{\pm}0.051$ in healthy controls (p<0.005), and the sensitivity and specificity of ELISA for serum IsM antibody were 70.0% and 96.7%, respectively. 3, The ELISA-IgG values showed a significant correlation with ELISA-IgM values(r=0.77, p<0.005) , With above results, it is assumed that ELISA is a reliable method for the diagnosis of T vaginalis infection and simultaneous measurement of serum IgG and IgM with this technique is recommended.