• 수산해양기술연구
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• 제5권1호
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• pp.14-20
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• 1969

$\circled1Connecting Spread를 일정하게 하고 Towing Line의 길이를 변화시킬 때 각 속도에 따른 망고 및 망폭 Towing line의 길이가 길어질수록 망고는 높아지고 망폭은 좁아진다. $\circled2$ Towing line의 길이를 일정하게 하고 Connecting Spread를 변화시킬 때 망고 및 망폭은 Connecting Spread가 넓어질 수록 망폭은 넓어지나 망고는 거의 변화가 없다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.357-364
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• 2002

This paper describes the feasibility of compacting subgrade layer in thicker lifts than currently permitted as 20 cm. This project involved constructing and testing a full scale test section in highway. Soil stiffness in field was evaluated by a nondestructive testing method, called Geogage. Quality control tests and FE Analysis were also conducted. Typical dynamic compaction roller of 11ton weight is applied for full scale test and a Mohr-Coulomb model and Plane strain condition are used for FE Analysis. The results showed that compaction-induced stress and dissipated energy are mainly depend on depth of soil and it could be possible to increase thickness of a lift.

• Child Health Nursing Research
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• 제14권1호
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• pp.22-34
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• 2008

Purpose: The purpose of this study was to build and test a theoretical model that could be used to explain and predict health promoting behavior in school children in Korea. Method: Participants for this study included a total of 423 students, all of whom were enrolled in either the 5th or 6th grade of one of 3 elementary schools in Seoul and Gyunggi Province, Korea. A questionnaire was used to collect the data and the collection period was from September 22 to 30, 2006. The data were analyzed using the SAS Program and Lisrel Windows Program. The instruments for this study were developed to include a health promotion behavior scale, self-esteem scale, self-efficacy scale, perceived benefit and barriers scale, social support scale, health status scale, academic stress scale, and previous health-related behavior scale. Results: The hypothetical model for this study consisted of 3 intrinsic and 6 extrinsic variables, and 27 pathways. As a result of hypotheses testing, as many as 11 pathways were found to be statistically significant. Conclusion: The development of health promotion programs based on the factors found in this study will be very effective in promoting the health of Korea's school children.

• 한국방사선학회논문지
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• 제12권6호
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• pp.745-753
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• 2018

방사선이 다양한 분야에 사용됨에 따라 방사선작업종사자의 수가 증가하고 있으며, 이에 따라 종사자의 안전에 대한 우려도 높아지고 있다. 국내에서는 KISOE 시스템, 발주자보고 등을 통해 종사자의 안전 확보에 주력하고 있다. 선행연구에서는 종사자 및 업체의 안전 확보를 위한 위험성 평가에 피폭선량과 더불어 이외의 항목에 대한 추가적 평가가 효과적일 것이라고 판단하여 평가를 위한 항목들 및 방사형 척도분석 모델을 개발하였다. 이에 본 연구에서는 2016년 방사선투과검사업체의 자료를 방사형척도분석 모델에 적용하여 실제 업체의 위험성 평가를 수행하였다. 또한 위험성이 낮을 것으로 예상되는 업체 2곳과 위험성이 높을 것으로 예상되는 업체 2곳을 선정하여 위험성 분석을 수행하였다. 분석 결과에서 예상과 동일한 결과를 얻어 모델의 타당성을 확인할 수 있었다. 전체 56개 업체의 위험성 평가가 수행되었고 업체별 문제점에 따른 개선 및 점검사항을 예측하였다. 본 연구 결과를 방사선투과검사업체 및 규제기관에서 자체 평가 및 규제 기준 등으로 활용할 수 있을 것으로 예상된다.

• 대한간호학회지
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• 제48권4호
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• pp.419-431
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• 2018

Purpose: The purpose of this study was to develop and establish the psychometric properties of a clinical nursing competency evaluation tool to be utilized by clinical preceptors. Methods: The initial items were identified through in-depth literature review and field interviews based on a hybrid model. Content validation of the items was evaluated through three rounds of content validity testing. Participants were 34 clinical preceptors and 443 nursing students participating in clinical practice. Data were analyzed using exploratory and confirmatory factor analysis, convergence and discriminant validity, internal consistency and inter-rater reliability. Results: The final scale consisted of 23 items and four factors, fundamental nursing skills performance, critical thinking skills based on the nursing process, basic nursing knowledge, and professional attitude; these factor explained 69.7% of the total variance. The analysis with multi-trait/multi-item matrix correlation coefficients yielded 100.0% and 95.7 % convergence and discriminant validity, respectively. Cronbach's alpha for the total items was .95. The four subscale model tested by confirmatory factor analysis was satisfactory. Inter-rater reliability ranged from .912 to .967. Conclusion: This scale was found to be a reliable and valid instrument that clinical preceptors can apply for evaluating the clinical nursing competency of nursing students in clinical settings.

• Wind and Structures
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• 제34권2호
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• pp.199-213
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• 2022

The current study investigates the dynamic effects in the tornado-structure response of an aeroelastic self-supported lattice transmission tower model tested under laboratory simulated tornado-like vortices. The aeroelastic model is designed for a geometric scale of 1:65 and tested under scaled down tornadoes in the Wind Engineering, Energy and Environment (WindEEE) Research Institute. The simulated tornadoes have a similar length scale of 1:65 compared to the full-scale. An extensive experimental parametric study is conducted by offsetting the stationary tornado center with respect to the aeroelastic model. Such aeroelastic testing of a transmission tower under laboratory tornadoes is not reported in the literature. A multiaxial load cell is mounted underneath the base plate to measure the base shear forces and overturning moments applied to the model in three perpendicular directions. A three-axis accelerometer is mounted at the level of the second cross-arm to measure response accelerations to evaluate the natural frequencies through a free-vibration test. Radial, tangential, and axial velocity components of the tornado wind field are measured using cobra probes. Sensitivity analyses are conducted to assess the variation of the structural dynamic response associated with the location of the tornado relative to the lattice transmission tower. Three different layouts representing the change in the orientation of the tower model relative to the components of the tornado-induced loads are considered. The structural responses of the aeroelastic model in terms of base shear forces, overturning moments, and lateral accelerations are measured. The results are utilized to understand the dynamic response of self-supported transmission towers to the tornado-induced loads.

• 콘크리트학회지
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• 제3권4호
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• pp.133-142
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• 1991

원형(prototype) 철근콘크리트 구조물의 거동을 축소모형실험을 이용하여 연구하기 위해서는 모든 구성재료의 물리적 성질들이 특정상사(similitude)관계 또는 1:1로 복제된 모형재료를 사용하여야 한다. 원형과 모형의 물리적 특성에 관한 상사성에 대해 사전 연구가 되어져야만 축소모형실험결과 해석에 적용할 수 있다. 본 연구는 철근콘크리트 구조물을 축소모형화하는데 따른 구성재료의 물리적 성질과 기본 거동에 관한 문제점들을 파악하고, 개선된 방법을 찾기 위한 것이다. 모형콘크리트에서 발견되는 큰 인장강도를 최소화하기 위해 배합비를 변화시켜서 원형콘크리트에 가장 가까운 모형콘크리트의 제작기법과 모형철근의 표면형태에 따른 거동의 차이를 단순보를 이용하여 연구하였다.

• International Journal of Reliability and Applications
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• 제15권2호
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• pp.85-98
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• 2014

Accelerated life testing (ALT) is a well famous technique in life testing and reliability studies, this is particularly used to induce so high stress leading to failure of the highly reliable units quickly under stipulated duration of time. The step-stress ALT is one of the systematic experimental strategy of ALT applied to fail the units in steps. In this article we focus on two important issues (i) necessity of life tests at higher steps with relevant causes (ii) to develop a new optimum test plan for 3-step SSALT under the modified cumulative exposure model proposed by Khamis and Higgins (1998). It is assumed that the lifetime of test units follows Rayleigh distribution and its scale parameter at constant stress level is assumed to be a log-linear function of the stress. The maximum likelihood estimates of the parameters involved in the step-stress ALT model are obtained. A simulation study is performed for numerical investigation of the proposed new optimum plan 3-step, step-stress ALT. The necessity of the life test units at 3-step step-stress is also numerically examined in comparison to simple step-stress setup.

• Wind and Structures
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• 제16권2호
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• pp.137-156
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• 2013

A wind tunnel test of a scaled-down model and field measurement were effective methods for elucidating the aerodynamic behavior of a chimney under a wind load. Therefore, the relationship between the results of the wind tunnel test and the field measurement had to be determined. Accordingly, the set-up and testing method in the wind tunnel had to be modified from the field measurement to simulate the real behavior of a chimney under the wind flow with a larger Reynolds number. It enabled the results of the wind tunnel tests to be correlated with the field measurement. The model surface roughness and different turbulence intensity flows were added to the test. The simulated results of the wind tunnel test agreed with the full-scale measurements in the mean surface pressure distribution behavior.

• 천문학회보
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• 제46권1호
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• pp.52.3-53
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• 2021

It is yet to be understood what controls the star formation activity in high-redshift galaxy clusters. One recently proposed mechanism is that the star formation activity in galaxy clusters are fed by gas and galaxies in large-scale structures surrounding them, which we call as "web feeding model". Using galaxies in the COSMOS2015 catalog, with mass completeness at log(M/M_⦿)≥9.54 and reliable photometric redshift data (σ_Δz/(1+z) ≲ 0.01), we study the star formation activities of galaxy clusters and their surrounding environment to test the web feeding model. We first identify the overdense regions with number density exceeding the 4σ-level from photometric redshift data as galaxy clusters, and we find that they are well matched with clusters identified in the X-ray extended source catalog. Furthermore, we identify galaxy large scale structures, and will present the correlation or anti-correlation between quiescent galaxy fraction, an indicator of star-forming activity, and the prevalence of galaxy large scale structures.