• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.1
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• pp.1-8
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• 2006

A linear acoustic analysis is conducted to examine bituning of acoustic resonators for acoustic damping in a combustion chamber of liquid rocket engine. Bituned resonators are tuned to the two principal modes, the first tangential(1T) and the first radial(1R) modes. First, the acoustic-damping effect of monotuned resonators is investigated. The damping capacity is quantified by damping factor as a function of the number of the resonators monotuned to 1T or 1R mode. Next, the damping characteristics of the bituned resonators are investigated. From the numerical data, the number of resonators, to be tuned to 1T and 1R modes, respectively, can be selected properly. Furthermore, the concept of resonator bituning is applied to reduce the degradation of damping effect caused by the mode split and thereby, optimal bituning frequencies are found.

• The Korean Journal of Emergency Medical Services
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• v.28 no.1
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• pp.7-19
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• 2024

Purpose: This study aimed to evaluate and assess the response capabilities and educational needs of 119 emergency medical technicians (EMTs) in chemical accidents. Methods: A self-reported questionnaire was completed by 167 119 EMTs between December 1st and December 31, 2023. The questionnaire comprised 8 questions on general characteristics, 2 on chemical accidents experienced by the participants, 29 on response capabilities, and 15 on educational needs. Data analysis was performed using t-tests, analysis of variance, Duncan's test for post-hoc analysis, and Pearson's correlation coefficient, using SPSS 27.0. Results: The participants scored 2.69 points on response capacity to chemical accidents. The EMT-Paramedics scored high in 'patient triage,' 'patient treatment,' 'patient transport,' and 'collaborative support' (F=3.924, p=.010; F=5.843, p=.001; F=3.698, p=.013; F=5.272, p=.002), followed by educational experience (t=-4.962, p<.001; t=-2.685, p=.008; t=-3.455, p=.001; t=-3.593, p<.001; t=-3.034, p=.003). The participants scored 4.19 points on educational needs, with high scores for 'patients treatment and transport' (4.280.93). The scores for 'patient triage competency', and 'patient triage' (r=.169, p=.024) correlated positively. Furthermore, the scores for 'patient treatment competency' and all sub-factors of educational needs (r=.185, p=.013; r=.215, p=.004; r=.199, p=.008; r=.190, p=.011; r=.197, p=.008) correlated positively. Conclusion: To strengthen the response capabilities of 119 EMTs, it is imperative to develop an educational program that focuses on first-aid responses.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.1
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• pp.31-37
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• 2006

The present study has been experimentally investigated the effect of geometric and operating parameters on the two-phase flow distribution of refrigerants in a horizontal T-junction. The operating parameters were the kind of refrigerants (R-22, R- l34a, and R-410A), saturated temperature, and the inlet mass flux and quality. The geometric parameters were the tube diameter and the tube diameter ratio. The measured data of refrigerants were compared with the values predicted using the models developed by several researchers for air/water or steani/water two-phase flow. Among the operating parameters, the inlet Quality was the most sensitive to the mass flow rate ratio. Between the geometric parameters, the tube diameter ratio was more sensitive than tube diameter.

• Journal of electromagnetic engineering and science
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• v.8 no.3
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• pp.96-99
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• 2008

This paper describes a $0.13-{\mu}m$ CMOS RF switch for $3{\sim}5$ GHz UWB band(mode 1). It can improve isolation characteristics between ports by using deep n-well RF devices while their source and body terminals are separated. From the measurement results, the proposed T/R switch is comparative to the on-wafer probing measurement results of the series-shunt T/R switches. When the proposed T/R switch operates as Tx mode, measured insertion loss from Tx to output port is less than 1.5 dB and isolation between Tx and Rx is more than 27 dB for $3{\sim}5$ GHz. Return loss for the Tx port is more than -10 dB and input P1dB is +10 dBm.

• Journal of Oral Medicine and Pain
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• v.24 no.1
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• pp.59-67
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• 1999

Personality characteristics of TMD patients was studied through the SCL-90-R. III patients were subjected at the Orofacial Pain Clinic, Dept. of Oral Medicine, PNUH, from 1991 to 1996. All the TMD patients were divided and analyzied comparatively by the ways of duration of present illness, severity of symptoms, associated symptoms, traumatic contributing factor, history of treatment, treatment modality, response to therapy and treatment outcomes. The obtained results were as follows; 1. Mean value of T-scores on 9 basic scales in all the groups was within normal range. 2. There showed higher levels of T-scores in the chronic group, the unimproved group and the discontinued group. 3. T-scores in the patients with severe symptom, associated symptoms, and history of treatment revealed higher.

• Journal of the Korean Institute of Rural Architecture
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• v.6 no.3
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• pp.39-48
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• 2004

The purpose of this study is to clarify the actual conditions of the plan composition of expressway service facilities. This study investigated the characteristics of both indoor space and outdoor space of 15 service facilities, and then analyzed attributes of users by the plan type along with their perception on the facility usage. The results of this study are summarized as follows; 1) When analyzing the attributes of expressway service facilities users, 36% respondents said that they used the expressway service facilities just to rest. The average distance of using the service plaza was found to be approximately 67km. 2) In terms of the indoor space of the expressway service facilities, as basic patterns, B(R+C+T)-type(53%), A(C+R+T)-type(40%), C(C+T+R)-type(7%) were found in order, all the service facilities need to expand them.

• Asian Journal of Turfgrass Science
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• v.10 no.1
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• pp.31-40
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• 1996

The mechanical expresion provides for the use of Soil property reserves and permanent protec-tion or improvement of soil resources in accordance with measurable standards. If the functions I (initial soil property), E (soil erosion), R (soil renewal), and M. (minimum allowable value) are assumed to be integrable in region A, erosion tolerance over a region is leaded to ${\int}_A{\int}I(m, cl, re, ch, b)dA-{\int}_A{\int}{\{\int}_{to}^{\infty}[E(w, re, c, re, ch, b, t)-R(m, ch, re, b, t)]dt}\dA{\geqq}{\int}_A{\int}M_i(m, cl, re, ch, b)dA$ were variable factors are m=parent material of soil, cl=climate, re=relief or topography, ch=soil characteristics, r=rain or water, w=wind, b=biota, and t=time.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.420-428
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• 1988

Root is supposed to be important role in growth and yield formation of soybeans and also there is expected to exist varietal differences between soybean root morphology and system. 30 soybean varieties including 10 Korean recommended, 10 Introduced and 10 Korean native varieties were grown at field and pot under standard culture condition. Top and root characteristics were investigated at V4, R1 and R5 stage and T/R relations, correlations with yield were calculated. Top characteristics showed significant difference between 3 variety groups of Korean recommended, Introduced and Korean native variety. Stem length at R1 stage and stem length, stem diameter, number of nodes, number of branches, number of pods and grain yield at R5 stage were significantly different top characteristics. Root characteristics showed significant difference between 3 variety groups were number of thick primary root at V4 stage, primary root angle and root cutting strength at R1 stage, thick root diameter and root dry weight at R5 stage. The correlations between top and root characteristics and soybean yield was greatly different by soybean variety groups, and the top characteristics was more highly correlated then root characteristics. All the top and root characteristics of Korean recommended variety showed no correlations with yield. However, leaf area, stem length, top dry weight in Introduced variety and leaf area, top dry weight, number of nodes, number of thick primary root in Korean native variety were highly correlated with soybean yield.

• Journal of Technology Innovation
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• v.17 no.1
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• pp.149-177
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• 2009

Today, the phase of modem war is very different from past war. That is, the winning of war depends on the ability to obtain information and high technology. The purposes of this research are to propose an effective R&D governance model in national defense sector and to present R&D strategy for obtaining core national defense technology. As a part of collaborative innovation, the strategy to exchange R&D results actively between the defense sector and the private sector will be discussed. The main contribution of this research is dearly defining the concept of R&D governance in national defense sector and applying it to an actual case. The national defense R&D governance model proposed in this paper is based on the characteristics of national defense R&D which are different from other industries. The analysis of business success factors for national defense R&D through the T-50 case study is presented in detail. The T-50 case study reveals the importance of strategic intent, core technology knowledge base, organizational structure, and project management.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.1
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• pp.1-11
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• 2010

Generation and transportation of runoff and pollutant loads within watershed generated eutrophication at Daecheong reservoir. To improve water quality at Daecheong reservoir, the best management practices should be developed and applied at upper watersheds for water quality improvement at downstream areas. In this study, two small watersheds of upper Daecheong reservoir were selected. The Long-Term Hydrologic Impact Assessment (L-THIA) model has been widely used for the estimation of the direct runoff worldwide. To apply the L-THIA ArcView GIS model was evaluated for direct runoff and water quality estimation at small watershed. And the Web-based Hydrograph Analysis Tool (WHAT) was used for direct runoff separating from total flow. As a result, the $R^2$ (Coefficient of determination) value and Nash-Sutcliffe coefficient value for direct runoff comparison at An-nae watershed were 0.81 and 0.71, respectively. And the $R^2$ value and Nash-Sutcliffe coefficient value at Wol-oe were 0.95 and 0.93. The $R^2$ value of BOD, TOC, T-N and T-P at An-nae watershed were BOD 0.94, TOC 0.81, T-N 0.94 and T-P 0.89. And the $R^2$ value of BOD, TOC, T-N and T-P at Wol-oe watershed were BOD 0.80, TOC 0.93, T-N 0.86 and T-P 0.65. The result that estimated pollutant loadings using the L-THIA ArcView GIS model reflected well the measured pollutant loadings except for T-P in Wol-oe watershed. With L-THIA ArcView GIS model, the direct runoff and non-point pollutant (NPS) loadings in the watershed could be analyzed through simple input data such as daily rainfall, land uses, and hydrologic soil group.