• Steel and Composite Structures
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• 제47권5호
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• pp.633-644
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• 2023

Taking a look at the previously published papers, it is revealed that there is a porosity index limitation (around 0.35) for the mechanical behavior analysis of the functionally graded porous (FGP) structures. Over mentioned magnitude of the porosity index, the elastic modulus falls below zero for some parts of the structure thickness. Therefore, the current paper is presented to analyze the vibrational behavior of the FGP Timoshenko beams (FGPTBs) using a novel refined formulation regardless of the porosity index magnitude. The silica aerogel foundation and various hydrothermal loadings are assumed as the source of external forces. To obtain the FGPTB's properties, the power law is hired, and employing Hamilton's principle in conjunction with Navier's solution method, the governing equations are extracted and solved. In the end, the impact of the various variables as different beam materials, elastic foundation parameters, and porosity index is captured and displayed. It is revealed that changing hygrothermal loading from non-linear toward uniform configuration results in non-dimensional frequency and stiffness pushing up. Also, Al - Al2O3 as the material composition of the beam and the porosity presence with the O pattern, provide more rigidity in comparison with using other materials and other types of porosity dispersion. The presented computational model in this paper hopes to help add more accuracy to the structures' analysis in high-tech industries.

• International Journal of Aeronautical and Space Sciences
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• 제17권4호
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• pp.518-525
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• 2016

This paper presents the characteristics of non-fundamental multi-mode combustion instability and the effects of high-harmonic components on the Rayleigh criterion. Phenomenological observations of multi-harmonic-mode dynamic pressure waves regarding the intensity of harmonic components and the source of wave distortion have been explained by introducing examples of second- and third-order harmonics at various amplitudes. The amplitude and order of the harmonic components distorted the wave shapes, including the peak and the amplitude, of the dynamic pressure and heat release, and consequently the temporal Rayleigh index and its integrals. A cause-and-effect analysis was used to identify the root causes of the phase delay and the amplification of the Rayleigh index. From this analysis, the skewness of the dynamic pressure turned out to be a major source in determining whether multi-mode instability is driving or damping, as well as in optimizing the combustor design, such as the mixing length and the combustor length, to avoid unstable regions. The results can be used to minimize errors in predicting combustion instability in cases of high multi-mode combustion instability. In the future, the amount of research and the number of applications will increase because new fuels, such as fast-burning syngases, are prone to generating multi-mode instabilities.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.447-452
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• 2012

Among the various elements affecting a customer's evaluation of automobile quality, buzz, squeak and rattle (BSR) are considered to be major factors. In most vehicle manufacturers, the BSR problems are solved by find-fix method with the vehicle road test, mainly due to various excitation sources, complex generation mechanism and subjective response. The aim of this paper is to develop the integrated experimental method to systematically tackle the BSR problems in early stage of the vehicle development cycle by resolving these difficulties. To achieve this aim, the developed experimental method ought to include the following requirements: to find and fix the BSR problem for modules instead of a full vehicle in order to tackle the problem in the early stage of the vehicle development cycle; to develop the exciter system including the zig and road-input-signal reproducing algorithm; to automatically localize the source region of BSR; to develop sound quality index that can be used to assess the subjective responses to BSR. Also, the BSR sound quality indexes based on the Zwicker's sound quality parameters using a multiple regression analysis. The four sound metrics from Zwicker's sound quality parameter are computed for the signals recorded for eight BSR noise source regions localized by using the acoustic-field visualized results. Then, the jury test of BSR noise are performed for participants. On a basis of the computed sound metrics and jury test result, sound quality index is developed to represent the harsh of BSR noise. It is expected that the developed BSR detection system and sound quality indexes can be used to reduce the automotive interior BSR noise in terms of subjective levels as well as objective levels.

• 대한지역사회영양학회지
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• 제17권4호
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• pp.429-439
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• 2012

The purpose of this study was to evaluate nutrients intakes, glycemic index (GI), glycemic load (GL) according to body mass index (BMI) in female college students (n = 320). The study subjects were divided into 3 groups based on their body mass index, an underweight group (BMI < 18.5 kg/$m^2$, n = 55), a normal group (18.5 kg/$m^2$ ${\leq}$ < 23 kg/$m^2$, n = 231), and an overweight group (23 kg/$m^2$ ${\leq}$ BMI < 25 kg/$m^2$, n = 34). The food and nutrition intake data obtained by administering a 3-day food record and were analyzed by using Can pro 3.0 software. Anthropometric measurements were collected from each subject. Body weights and BMI of the underweight group were 45.9 kg, 17.6 kg/$m^2$, those of the normal group were 53.8 kg, 20.5 kg/$m^2$, and those of overweight group were 62.6 kg, 23.8 kg/$m^2$, respectively. The mean daily dietary GI of underweight, normal and overweight groups was 66.2, 65.8 and 66.5, respectively. These differences were statistically non-significant. The mean daily dietary GL of underweight, normal and overweight groups were 159.2, 149.4, and 148.9, respectively. The major food source of dietary GI and GL was rice in the three groups. Dietary GI and GL were not significantly correlated with obesity when adjusted for energy, carbohydrate and dietary fiber intake.

• 혜화의학회지
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• 제14권1호
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• pp.15-22
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• 2005

Source : sources used by Qianghuo is Ostericum koreanum Maximowicz, Notopterygium incisum Ting and Notopterygium forbesii Boissier etc. in Korea and China. And we cirulate a Qianghuo dividing Nanqianghuo and Beiqianghuo. Thought source of Korea Qianghuo is different from china's we use a same name. And source of Beiqianghuo has not made clear yet. According to research accomplished 2002, we have to use Nanqianghuo producted at Jinbu in aspect of aspect. but, Beiqianghuo the outside form of Beiqianghuo similar to china so we think that we have to more make clear source of domestic Qianghuo, verify a source Beiqianghuo and re-establish about effects and functions of domestic Qianghuos. Culture : A term of culture is an nearly one year. so to product Qianghuo of good quality, we must plant directly in autumn or raise seedlings and transplant in spring. Processing : To protect turning to brown, Qianghuo are cirulate mostly as the original form without washing in water, To proteet crushing of Qianghuo when we cut off, Qianghuo were cut off after being soaked in water or steamed by heat. So when we wash and cut off, it has to be made processes which have no decreases of medical effects and be suggested a proper index which verify a medical effects. In summury, after harvesting Qianghuo the first washing $\rightarrow$ the first dry $\rightarrow$ selection $\rightarrow$ the second washing $\rightarrow$ the second dry $\rightarrow$ selection $\rightarrow$ cutting off $\rightarrow$ the third dry.

• 한국물환경학회지
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• 제23권4호
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• pp.482-489
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• 2007

Fluorescence properties and carbohydrate content were investigated using ultrafiltrated size fractions of dissolved organic matters (DOM) originated from different sources. The materials included a treated sewage, an algal organic matter, and a soil leachate, all of which are major constituents of dissolved organic matter in a typical urban river. Four different size fractions were separated from the three sources of each DOM. The size distribution demonstrated that a higher molecular weight fraction was more present in soil leachate compared to two other source DOMs. A higher content of carbohydrates was observed in the following order - algal DOM > treated sewage > soil leachate. A wide range of specific UV absorbance was observed from size fractions of a single source DOM, indicating that aromatic carbon structures are heterogeneously distributed within one source of DOM. The structural heterogeneity was the most pronounced for the soil leachate. The fluorescence index ($F_{450}/F_{500}$) of the treated sewage was similar to that (2.0) typically obtained from autochthonous DOM, suggesting that the treated sewage exhibited autochthonous organic matter-like properties. No protein-like fluorescence intensities were observed for all of the soil leachate size fractions whereas they were observed with two other source DOMs. Based upon the fluorescence peak ratios from fluorescence excitation-emission matrix (EEM), two discrimination indices could be suggested to distinguish three different source DOMs. It is expected that the suggested discrimination indices will be useful to predict the sources of DOM in a typical urban river affected by treated sewage.

• 한국결정성장학회지
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• 제19권2호
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• pp.61-65
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• 2009

본 논문에서는 형광체가 없는 백색 LED의 성장과 광학적인 특성을 분석하였다. 혼합소스(miked-source) HVPE(hydride vapor phase epitaxy) 방법과 다중성장보트를 이용하여 MOCVD로 얇게 성장한 n-GaN 위에 활성층을 AlGaN으로 한 이종접합구조(DH; Doublehetero structure)를 성장하고, 패키징 단계를 거쳐 비형광체 단일칩 백색 LED 램프를 제작하였다. 패키징 한 소자를 주입전류 $10{\sim}100mA$로 변화시켜 측정한 결과 색 연색성 값은 72-93, 색좌표의 좌표값은 X값은 $0.26{\sim}0.34$, Y값은 $0.31{\sim}0.40$에서 가지며, 색온도는 $5126{\sim}10406K$ 범위에서 측정되었다. 또한 주입전류 증가 시, 형광체를 사용한 백색 LED는 청색 영역으로 이동하지만, 제작된 백색 LED는 황색영역으로 색좌표가 이동하였다. 이러한 특성을 통하여 고감도의 색 연색성 값을 가지는 비형광체 백색LED의 성장 가능성을 확인하였으며, 광 특성 분석 결과를 통하여 혼합소스의 성장 메커니즘을 제안하고자 한다.

• Korean Chemical Engineering Research
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• 제59권2호
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• pp.254-259
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• 2021

고밀도 C4F8 플라즈마에서 증착된 불화탄소막의 광학적 및 전기적 특성을 소스파워와 압력을 변화하며 분석하였다. 고밀도 C4F8 플라즈마에서 증착된 불화탄소막의 F/C 비율은 2단계 증착 메커니즘의 작용으로 소스파워가 증가할수록 증가하였고 압력이 증가할수록 감소하였다. 고밀도 C4F8 플라즈마에서 증착된 불화탄소막의 F/C 비율 변화는 불화탄소막의 광학적 및 전기적 특성 변화에 직접적으로 영향을 끼쳤다. 즉, 불화탄소막의 굴절률은 F/C 비율 변화 양상과는 달리 소스파워가 증가할수록 감소하였고 압력이 증가할수록 증가하였는데 이는 F/C 비율이 증가할수록 전자분극작용이 억제되고 불화탄소막의 망상조직이 약화되어 굴절률이 감소하기 때문이었다. 불화탄소막의 비저항은 F/C 비율 변화와 같이 소스파워가 증가할수록 증가하였고 압력이 증가할수록 감소하였는데 이는 F/C 비율이 증가할수록 주변 전자들을 반발하려는 경향이 강해져서 비저항이 증가하기 때문이었다. 고밀도 C4F8 플라즈마에서 증착된 불화탄소막의 F/C 비율 조절로 불화탄소막의 광학적 및 전기적 특성을 직접적으로 변화할 수 있으므로 불화탄소막이 반도체소자제조공정에서 저 유전상수 물질 대체용으로 가능할 수 있음이 예상된다.

• 동아시아식생활학회지
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• 제21권2호
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• pp.174-184
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• 2011

The purpose of this study was to evaluate nutrients intakes, glycemic index (GI), glycemic load (GL) according to obesity index in elementary school students. The study subjects included 229 elementary school students (boys=108, girls=121) who were divided into 3 groups consisting of an underweight group (obesity index<-10%, n=58), a normal weight group (10%${\leq}$ obesity index<10%, n=130) and an overweight group (obesity index${\geq}$10%, n=41) by their obesity index. The nutrient and food intakes data obtained by a 3-day food record were analyzed. Daily dietary GI and GL values were calculated from the 3-day food record. The average age of the subjects was 11.9 years. The mean daily energy intake was 2,186.8 kcal in the underweight group, 2,123.5 kcal in the normal weight group, and 2,174.2 kcal in the overweight group. The intakes of calcium and animal calcium per 1,000 kcal in the overweight group were significantly lower than in the underweight and normal weight groups (p<0.01, p<0.05), and fruit, egg and milk intakes in the overweight group were lower than those in the underweight group (p<0.05, p<0.05, p<0.05). The mean daily dietary GI of the underweight, normal weight, and overweight groups were 67.7, 68.4 and 69.5, respectively (p<0.05). The mean daily dietary GL of the underweight, normal weight, and overweight groups were 212.8, 208.1 and 213.3, respectively. The major food source of dietary GI and GL in the three groups was rice. Other major food sources of dietary GI were croquettes, hand-rolled noddle soups, instant noddles, milk, and rice cake. Dietary GI was not significantly correlated with weight, obesity or body mass index, when adjusted for energy, carbohydrate, and dietary fiber. However, GL adjusted to energy, carbohydrate and dietary fiber tended to correlate with obesity index (r=0.126, p=0.059). These results suggest that dietary GI and GL have possibility affecting obesity-related indicators in elementary school students.

• 한국포장학회지
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• 제22권3호
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• pp.163-168
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• 2016

본 연구에서는 국내 페트병의 경량화 가능성을 파악하기 위해 780종 이상의 빈용기 무게와 표시 용량의 상관관계를 분석하였다. 페트병은 사용목적에 따라 상압병(생수류), 내열병(쥬스류), 내압병(탄산류), 및 장기보관사용병(소스류)으로 구분하였으며 수집된 빈용기 무게와 표시 용량을 기반으로 각 페트병 종류별 경량화 지수(Lightness Index; L)를 산출하였다. 페트병 원천감량 설계 시 이용가능한 권고 기준 및 최적 기준을 경량화 지수를 이용하여 설정하였다. 예로 500 mL 생수병을 감량화 설계 기준에 맞게 생산할 경우 최적기준 반영시 약 4 g의 감량화가 가능하다. 작성된 설계 기준은 이미 관련 업계에 배포되었으며 생수병을 중심으로 적정 기준 정도의 경량화가 이루어지고 있다. 제시된 페트병 설계 기준은 국내외에서 출시된 페트병을 분석하여 무게 분포 특성을 반영한 결과이므로 현재 출시된 제품의 경량화 정도와 향후 개발되는 제품이 시장에서 어느 정도의 원천감량설계인지 알 수 있는 자료로 활용될 수 있을 것이다.