• Journal of Biosystems Engineering
• /
• 제18권3호
• /
• pp.209-219
• /
• 1993

A series of soil bin experiment was carried out on sand to investigate if true model theory is applicable to blade-soil system and finally to find mathematical relationship between the dimensionless terms which contain the blade-soil parameters. The following conclusions were derived from the study. 1. It was proved that the draft of the prototype blade can be predicted without distortion by those of model blades with the length scale of 1.2, 2 and 2.4. 2. For the sand, bulk density was found to be a good measure of soil physical properties which are pertinent to predict the draft of the blade-soil system. 3. The mathematical relationship between $D/{\gamma}W$ and d/W, ${\beta}$, and $V^2/Wg$ are as follows ; $$\frac{D}{{\gamma}W^3}=124.98[\frac{d}{W}]^2+7.16[\frac{d}{W}]+0.43 \\ \frac{D}{{\gamma}W^3}=-0.00099{\beta}^2+0.13{\beta}-2.01 \\ \frac{D}{{\gamma}W^3}=0.041[\frac{V^2}{Wg}]^2+0.08[\frac{V^2}{Wg}]+1.3$$

• Steel and Composite Structures
• /
• 제43권5호
• /
• pp.639-660
• /
• 2022

The bending and buckling behaviours of FG-GRNC laminated sandwich plates are investigated by using novel five-variables quasi 3D higher order shear deformation plate theory by considering the modified continuum nonlocal strain gradient theory. To calculate the effective Young's modulus of the GRNC sandwich plate along the thickness direction, and Poisson's ratio and mass density, the modified Halpin-Tsai model and the rule of the mixture are employed. Based on a new field of displacement, governing equilibrium equations of the GRNC sandwich plate are solved using a developed approach of Galerkin method. A detailed parametric analysis is carried out to highlight the influences of length scale and material scale parameters, GPLs distribution pattern, the weight fraction of GPLs, geometry and size of GPLs, the geometry of the sandwich plate and the total number of layers on the stresses, deformation and critical buckling loads. Some details are studied exclusively for the first time, such as stresses and the nonlocality effect.

• 한국학교보건학회지
• /
• 제26권3호
• /
• pp.184-194
• /
• 2013

Purpose: The purpose of this study was to investigate predictors of behavior problems of military children in elementary school. Methods: Participants were 195 military children who were attending D-elementary school in C-city. Data were collected from July 8 to July 10, 2013, using self-report questionnaires which included Han's Externalized Behavior Problems Scale, Lee's Parent's Rearing Attitude Scale, and Hong's Friend/Teacher Support Appraisal Scale. Data analysis was performed using the SPSS/WIN 18.0 program, which included the t-test, the one-way ANOVA, Pearson correlation coefficients, and the multiple liner regression analysis. Results: The mean score of the subjects' behavior problem was 1.47/5.0 points. The degree of the score is similar to or slightly lower than that of ordinary children. There were statistically significant differences in behavior problems according to gender, grade, birth order and economic status. Behavior problems have a negative correlation with parent's rearing attitude, parent-child relationship, teacher's support, and friend's support. Influencing factors of behavior problems were teacher's support, father-child relationship, and mother's rearing attitude, which explained 20.6% of the variance. Conclusion: The finding of this study suggests there is a need to increase teacher's support for elementary students and to educate parents to improve their parenting skills by developing proper school health programs.

• 아동학회지
• /
• 제32권6호
• /
• pp.33-48
• /
• 2011

This study examined the relationships between place attachment to home, acculturative stress, and psychological adjustment among Korean youth in the United States. In particular, this study sought to better understand how place attachment to home and acculturation stress impacts upon youth's psychological adjustment, as measured by depression and self-esteem. The subjects consisted of 225 Korean youths (113 males and 111 females) residing in Michigan in the USA, of whom 47.6% attended middle school while 52.4% of whom attended high school. The instruments utilized were the acculturative stress scale (Sandhu and Asrabadi, 1994), the place attachment scale (Choi, Lee, & Han, 2009), Radloff's depression scale (CES-D), and Rosenberg's self-esteem scale. Hierarchical multiple regression analyses were used to assess the predictive effects of place attachment to home and acculturative stress on youth's psychological adjustment, alongside controlling demographic variables. The findings indicated that place attachment to home and acculturative stress impacted upon depression and self-esteem, as experienced by the youths examined. These results have implications for our understanding of the importance of both youths' place attachment to home and acculturative stress in the acculturation process.

• 화약ㆍ발파
• /
• 제8권1호
• /
• pp.3-16
• /
• 1990

The cautious blasting works had been used with emulsion explosion electric M/S delay caps. Drill depth was from 3m to 6m with Crawler Drill $\varphi{70mm}$ on the calcalious sand stone(sort-moderate-semi hard Rock). The total numbers of feet blast were 88. Scale distance were induces 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagtion Law in Blasting Vibration $V=K(\frac{D}{W^b})^n$ where V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites (m) W : Maximum Charge per delay-period of eighit milliseconds or more(Kg) K : Ground transmission constant, empirically determind on th Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents Where the quantity $D/W^b$ is known as the Scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagrorized in three graups. Cabic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge per delay Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom and over loom distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m----under l00m----- $V=41(D/3\sqrt{W})^{-1.41}$ -----A Over l00m-----$V= 121(D/3\sqrt{W})^{-1.66}$-----B K value on the above equation has to be more specified for furthur understang about the effect of explosives, Rock strength. And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• 화약ㆍ발파
• /
• 제9권4호
• /
• pp.3-12
• /
• 1991

The cautious blasting works had been used with emulsion explosion electric M /S delay caps. Drill depth was from 3m to 6m with Crawler Drill 70mm on the calcalious sand stone (soft-moderate-semi hard Rock) . The total numbers of feet blast were 88. Scale distance were induces 15.52-60.32. It was applied to Propagation Law in blasting vibration as follows .Propagtion Law in Blasting Vibration V=k(D/W/sup b/)/sup n/ where V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W ; Maximum Charge per delay -period of eight milliseconds or more(Kg) K : Ground transmission constant, empirically determind on the Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents Where the quantity D/W/sup b/ is known as the Scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagrorized in three groups. Cabic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge delay Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom and over loom distance because the frequency is varified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m--under 100m----V=41(D/ W)/sup -1.41/-----A Over l00m---------V=121(D/ W)/sup -1.56/-----B K value on the above equation has to be more specified for furthur understand about the effect of explosives. Rock strength, And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• 지질공학
• /
• 제32권4호
• /
• pp.449-466
• /
• 2022

지하공간을 구성하고 있는 지중구조물, 지반, 암반 등 다양한 구성 요소 중에 지질공학적 측면을 포함한 모든 정보에 대한 모델 구축은 현실적으로 어려운 과정이며, 현재 진행형인 분야이다. 본 연구에서는 지질공학적인 정보모델 구축 과정이 비교적 쉬운 상용 소프트웨어를 활용하여 제주도 일부 지역 대상의 3차원 지질정보모델, 동굴형상정보모델, 도로 주변 현황 정보모델까지 한 번에 디지털화하는 과정이 포함되어 있다. 제주도에 존재하는 수많은 자연동굴 중에 도로와 교차하는 위치 중 제주도 한림 재암천굴을 대상으로 CaveBIM 기반의 디지털 트윈 구축에 관한 연구를 수행 중이다. 본 연구에서는 3D 레이저 스캐너를 사용한 동굴 형상 정보모델링, 지질 정보 및 지구물리탐사 자료를 활용한 3D 지질 모델링, 드론을 활용한 재암천굴 상부 도로 주변 현황 정보모델링 등의 개별 데이터 구축과 통합을 통해서 디지털화하는 과정을 포함하고 있다. 본 연구에서는 한림-제주 지역에 대한 전역모델(GSM) 및 재암천굴에 대한 국부모델(LSM)을 구축하였다. 또한 재암천굴에 대한 LSM 구축 시 교차검증을 수행하여 결과를 비교 및 분석하였다.

• 한국가스학회지
• /
• 제21권5호
• /
• pp.45-55
• /
• 2017

대부분의 가연성가스의 누출 및 화재/폭발 등의 실험은 큰 위험성이 있으며 실험을 진행할 수 있는 부지 선정에 큰 어려움이 있어 가급적 전산유동해석(CFD) 등의 간접적 방법을 많이 활용하였다. 그러나 2016년 10일 강원도 영월군에 에너지안전실증연구센터가 개소함에 따라 대규모/고압/초저온 등의 실험 뿐아니라 소규모 가연성 가스의 누출 및 검지 실험이 가능하게 되어 본 실험을 계획하였다. 본 실험에서는 가스센서를 교정하고 가스가 누출될 공간에 배치 후 LP가스를 누출시켜 가스센서에 검지된 값을 Contour map으로 가시화하였다. 또한 동일 조건으로 해석한 전산유동해석 결과값과 비교하여 LEL 25% 값의 실제 누출(28s, 최대 3.7m)의 차이점에 대해 분석하였다.

• 동의신경정신과학회지
• /
• 제32권3호
• /
• pp.155-166
• /
• 2021

Objectives: To analyze correlation between CSEI-S and MMPI-2 subscales to provide evidence for clinical application of the CSEI-S. Methods: Survey data of CSEI-S and MMPI-2 from 109 university students were analyzed. Demographic characteristics were subjected to descriptive analysis. Mann-Whitney U test and Pearson's correlation analysis were performed for CSEI-S and MMPI-2 scores. Results: The CSEI-S scale Joy (喜) showed a negative correlation with MMPI-2 clinical scales Hs, D, Hy, Pd, Pa, Pt, Sc, and Si. Six negative emotion scales of the CSEI-S showed positive correlations with MMPI-2 clinical scales except Mf and Ma. The CSEI-S scale Joy (喜) showed negative correlations with MMPI-2 restructured clinical scales RCd, RC1, RC2, and RC7. Six negative emotion scales of the CSEI-S showed positive correlations with restructured MMPI-2 clinical scales. The 60T-and-over group of MMPI-2 clinical scales D, Pd, Pa, Pt, Sc, Si, and Si showed significantly higher negative emotions than other groups. The 60T-and-over group of MMPI-2 scales D, Pt, Sc, and Si showed significantly lower Joy (喜) score than other groups. The 60T-and-over group of MMPI-2 restructured clinical scales RCd, RC2, RC3, RC6, RC7, RC8, and RC9 showed significantly higher negative emotions than other groups. The 60T-and-over group of MMPI-2 scales RCd, RC6, and RC7 showed significantly lower Joy (喜) scores than others. Conclusions: The CSEI-S showed consistent results with the original CSEI and MMPI-2 subscales. Thus, is a useful diagnostic tool in clinical practice.

• 한국잠사곤충학회지
• /
• 제49권1호
• /
• pp.28-32
• /
• 2007

누에체액이 동물세포 배양의 필수첨가물인 FBS를 대체할 수 있는 세포증식 효과가 있는 것으로 확인되었으나, 누에의 배발에 상처를 내어 채혈하는 방법으로는 대량 채취가 어렵다. 본 연구에서는 이러한 문제점을 해결코자 대량의 체액을 한꺼번에 얻을 수 있는 대규모 채혈법을 검토하게 되었다. 1. 누에 머리부분과 꼬리부분(배발 포함)에 상처를 낸 후 원심하여 체액을 채취하는 방법(절피원심법)이 기존의 소규모 채취한 체액과 유사한 세포증식 촉진효과를 보였다. 2. 절피원심한 체액의 원심속도에 따른 세포증식 촉진 효과는 500rpm과 1000rpm에서 양호한 값을 보였다. 3. 원심속도를 500rpm으로 고정한 경우 원심시간을 5분에서 30분까지 달리하여도 세포증식 효과는 유사하였고, 체액 회수율은 원심시간이 길어질수록 증가하였으나 일정시간 이상부터는 증가하지 않았다. 4. 절피원심법으로 대규모 채취한 체액의 액상회수율은 누에(백옥잠)생체중의 19.5%이었고, 분말회수율은 1.4% 이었으며, 분말체액에서도 세포증식 촉진 효과가 인정되었다.