• 천문학회보
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• 제46권1호
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• pp.47.3-47.3
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• 2021

In this talk I will review recent progress that the SDSS-IV / eBOSS collaboration has made in constraining cosmology from the clustering of galaxies, quasars and the Lyman-alpha forest. The SDSS-IV / eBOSS collaboration has measured the baryon acoustic oscillation (BAO) and redshift space distortion (RSD) features in the correlation function in redshift bins from z~0.15 to z~2.33. These features constitute measurements of angular diameter distances, Hubble distances, and growth rate measurements. A number of consistency tests have been performed between the BAO and RSD datasets and additional cosmological datasets such as the Planck cosmic microwave background constraints, the Pantheon Type Ia supernova compilation, and the weak lensing results from the Dark Energy Survey. Taken together, these joint constraints all point to a broad consistency with the standard model of cosmology LCDM + GR, though they remain in tension with local measurements of the Hubble parameter.

• 식물분류학회지
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• 제49권1호
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• pp.28-69
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• 2019

한국산 양지꽃족(tribe Potentilleae) 식물 7속 24종에 대하여 외부형태 형질과 과실 미세구조 관찰 및 문헌 조사를 통한 분류학적 연구를 수행하였다. 화주가 암술에 위치하는 특징과 화주의 모양은 양지꽃족의 아족 및 속간 분류에 유용한 형질이었다. 딸기아족(subtribe Fragariinae)은 화주가 아기저생 또는 측생하였으며 수술에는 1개의 화분낭을 갖는 반면에, 양지꽃아족은 화주가 대부분 자방에 아정생하며, 드물게 측생하고, 수술에 2개의 화분낭을 갖는 특징으로 구분되는 것으로 밝혀졌다. 딸기아족에는 물싸리속, 물싸리풀속, 검은낭아초속, 딸기속이 포함되며, 각 속은 양지꽃속과는 구분되는 독립된 속으로의 처리를 지지한다. 양지꽃속으로 처리되어 왔던 눈양지꽃은 양지꽃아족에서 유일하게 화주가 측생/아정생하는 특징과 탁엽이 엽병의 앞면에 부착하는 특징으로 독립된 눈양지꽃속으로 처리됨을 지지한다. 종 수준에서의 연구 결과 흰땃딸기(딸기속)는 식물체가 잎 포함하여 전반적으로 작고, 한라산에서만 제한 분포하는 특징으로 특산종으로 처리가 타당하다고 판단된다. 산뱀딸기(뱀딸기속)는 뱀딸기에 비하여 잎이 연한 녹색 또는 황녹색, 소엽이 얇고 다소 막질이며, 넓은 난형 또는 도란형의 소엽 등을 갖는 특징으로 뱀딸기와 잘 구분된다. 다양한 외부형태학적 변이를 보여 분류군의 한계에 대한 논란이 있어 왔던 양지꽃속의 돌양지꽃 복합체와 딱지꽃 복합체에 대하여 추가적인 분류학적 연구와 개체군 수준에서의 분자분류학적 연구가 필요하다.

• 천문학회보
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• 제39권2호
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• pp.43.2-43.2
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• 2014

We present the three-dimensional genus topology of large-scale structure using the CMASS sample of the Final SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) data. To estimate the uncertainties in the measured genus, we very carefully construct mock CMASS surveys along the past light cone from the Horizon Run 3. We find that the shape of the observed genus curve agrees very well with the prediction of perturbation theory and with the mean topology of the mock surveys. However, comparison with simulations show that the observed genus curve slightly deviates from the theoretical Gaussian expectation. From the deviation, we further quantify the primordial non-Gaussian contribution.

• 한국조리학회지
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• 제24권3호
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• pp.133-143
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• 2018

The purposes of this study was to investigate how interpersonal relationship stress had the impact on job attitude and turnover intention. To perform this study, total 420 questionnaire were distributed to regular hotel employees from October 16th to November 26th in 2017. Unworkable data were excluded, and final 344 usable responses were obtained for an empirical analysis. Frequency analysis, exploratory factor analysis, reliability analysis, correlation analysis and regression analysis were measured by using SPSS 18.0, respectively. For the study structure, interpersonal relationship stress primarily concentrated on the boss/staff/colleague/customer stress. Job attitude was divided into organization commitment and job satisfaction. Transfer intention was a single factor. The results of this study were shown as follows: Hypothesis 1, boss/customer stress have a negative effect on organization commitment and boss/colleague/customer stress have a negative effect on job satisfaction. Hypothesis 2, boss/customer stress have a positive effect on transfer intention. Hypothesis 3, tissue commitment have a negative effect on transfer intention. This results of this study have shown that stress management of employee is a source of management result in hotel business. This study have given to the hotel's human resource management and internal marketing for the practical implication and academical use.

• Tribology and Lubricants
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• 제36권3호
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• pp.168-192
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• 2020

In recently designed diesel engines, the running conditions for piston-pin bearings have become severe because of the higher combustion pressure and increased temperature. Moreover, the metal removal from the bushing material has strongly reduced the ability of the antifriction material to accept asperity contacts. Therefore, it is necessary to find ways of reducing wear scar on the connecting-rod small-end bushing and piston-pin boss bearing related to the higher combustion pressure on the power cell of an engine. In this work, the position and level of material removal from the surfaces of the bushing and bearing under such severe operating conditions - for example, maximum power and torque conditions of a passenger car diesel engine - are estimated for several combinations of surface roughness. First, piston-pin rotating motion is investigated by calculating the friction coefficient at piston-pin bearings, the oil film thickness, and the frictional torques induced by hydrodynamic shear stress. Subsequently, the wear scarring on the surfaces of a connecting-rod small-end bushing and two piston-pin boss bearings related to piston-pin rotational motion is numerically calculated under the maximum power and torque operating conditions. This work is helpful to determine the reasonable surface roughness of the bushing and bearing for reducing wear volume occurring at the interface between a bearing and a shaft.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.405-410
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• 2005

현재 압력이나 가속도를 측정하기 위해 사용되는 반도체 센서 중에서 압저항 센서가 가장 광범위하게 적용되고 있다. 이러한 압저항 센서는 반도체 공정에 의해서 제작되고, 기존의 센서보다 높은 민감도를 가지므로 그 적용성이 매우 높다. 하지만, 압저항 센서를 형성하는 구조물의 형상과 관련된 연구가 국내에서 미비하므로 이에 대한 연구가 요구된다. 본 연구에서는 과도한 압력에 센서를 보호하기 위한 보스(Boss)와 민감도 향상을 위해 사용되는 매스(Seismic Mass)의 기하학적 변화가 민감도에 미치는 영향을 압저항 분포를 통하여 분석하고, 적절한 위치와 크기를 제시하고자 한다.

• 한국추진공학회지
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• 제20권6호
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• pp.29-37
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• 2016

본 논문에서는 유한요소해석을 이용하여 복합재 연소관의 금속 보스에 대한 형상 최적설계기법을 제안하였다. 복합재 연소관의 구조 안전성을 위해 연소관 내압에 의한 돔 부위의 섬유응력과 보스 체결 볼트의 응력을 제한하였고, 경량화를 위해 보스의 무게를 목적함수로 설정하였다. 또한 반응표면법을 이용하여 특성치에 대한 반응표면모델을 구축하였다. 그리고 분산분석을 이용해 각 특성치에 대한 설계변수의 유의성을 평가하고 회귀분석을 통해 구축된 모델의 적합성을 검증하였다. 최적화를 위해 순차이차계획법 알고리즘을 이용하였고, 도출된 최적형상에 대한 구조해석을 수행함으로써 제안한 기법의 효용성을 검증하였다.

• 식물분류학회지
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• 제50권1호
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• pp.8-16
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• 2020

Complete chloroplast genome sequences provide detailed information about any structural changes of the genome, instances of phylogenetic reconstruction, and molecular markers for fine-scale analyses. Recent developments of next-generation sequencing (NGS) tools have led to the rapid accumulation of genomic data, especially data pertaining to chloroplasts. Short reads deposited in public databases such as the Sequence Read Archive of the NCBI are open resources, and the corresponding chloroplast genomes are yet to be completed. The V. dilatatum complex in Korea consists of four morphologically similar species: V. dilatatum, V. erosum, V. japonicum, and V. wrightii. Previous molecular phylogenetic analyses based on several DNA regions did not resolve the relationship at the species level. In order to examine the level of variation of the chloroplast genome in the V. dilatatum complex, raw reads of V. dilatatum deposited in the NCBI database were used to reconstruct the whole chloroplast genome, with these results compared to the genomes of V. erosum, V. japonicum, and three other species in Viburnum. These comparative genomics results found no significant structural changes in Viburnum. The degree of interspecific variation among the species in the V. dilatatum complex is very low, suggesting that the species of the complex may have been differentiated recently. The species of the V. dilatatum complex share large unique deletions, providing evidence of close relationships among the species. A phylogenetic analysis of the entire genome of the Viburnum showed that V. dilatatum is a sister to one of two accessions of V. erosum, making V. erosum paraphyletic. Given that the overall degree of variation among the species in the V. dilatatum complex is low, the chloroplast genome may not provide a phylogenetic signal pertaining to relationships among the species.

• 산업융합연구
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• 제20권11호
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• pp.95-104
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• 2022

본 연구는 보육교사 400명을 대상으로 상사무례경험과 플로리싱의 관계에서 복지와 희망이 단순 및 이중 매개하는 지를 분석하여 플로리싱 증진을 위한 기초자료를 제공하는데 목적이 있다. 자료는 오프라인 설문지를 통하여 수집하였으며, SPSS PC+ Win ver. 25.0과 SPSS PROCESS macro ver. 4.1을 활용하여 분석하였고, 빈도분석, 신뢰도분석, 상관분석 및 이중 매개효과 분석을 실시하였다. 연구결과 첫째, 상사무례경험은 복지, 희망 및 플로리싱과 부적인 상관관계를 보였고, 복지, 희망 및 플로리싱은 서로 정적인 상관관계를 보였다. 둘째, 복지와 희망은 상사무례경험과 플로리싱의 관계에서 이중 매개역할을 하였다. 복지와 희망 두 매개변인은 무례경험이 플로리싱에 미치는 음(-)의 영향을 부분적으로 상쇄시키는 역할을 하였다. 결론적으로 복지와 희망의 이중 매개역할을 이용하여 플로리싱을 증진할 수 있음을 확인하였다.

• 한국기계가공학회지
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• 제20권5호
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• pp.128-134
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• 2021

A press-fitted shaft is an essential part used in industrial machines, and it is generally used to transmit large quantities of power. Very high contact pressure occurs at the end parts of the contact between the shaft and boss, which are press-fitted shaft components. Such contact pressure not only damages the contact surface of a press-fitted shaft but also reduces its fatigue strength. To improve a press-fitted shaft's fatigue strength, the contact pressure on the contact surface, which directly affects the fatigue strength, should be minimized. Thus, in this study, the design configuration optimization of the end part of the boss was based on the approximate optimization method and was aimed at minimizing the contact pressure at the end of a press-fitted shaft. Comparison of the contact pressure and the contact stress of a conventional press-fitted shaft with those of the optimized press-fitted shaft showed that the boss design of the optimized press-fitted shaft effectively improved the fatigue life.