• 한국지진공학회논문집
• /
• 제24권1호
• /
• pp.39-47
• /
• 2020

Lightly reinforced concrete (RC) moment frames may suffer significant damage during large earthquake events. Most buildings with RC moment frames were designed without considering seismic loads. The load-displacement response of gravity load designed frames could be altered by masonry infill walls. The objective of this study is to investigate the load-displacement response of gravity load designed frames with masonry infill walls. For this purpose, three-story gravity load designed frames with masonry infill walls were considered. The masonry infilled RC frames demonstrated larger lateral strength and stiffness than bare RC frames, whereas their drift capacity was less than that of bare frames. A specimen with a partial-height infill wall showed the least drift capacity and energy dissipation capacity. This specimen failed in shear, whereas other specimens experienced a relatively ductile failure mode (flexure-shear failure).

• 항공우주의학회지
• /
• 제31권3호
• /
• pp.73-76
• /
• 2021

Changes the gravity has a significant affect on the immune system. Astronauts experience the gravity changing during spaceflight, especially when launching and landing they experience hypergravity, and during spaceflight they feel microgravity. Both hypergravity and microgravity has an impact to the immune system, but not the same effect. These impacts have been investigated extensively during spaceflight in astronauts and in model experiments conducted on Earth as well. Astronauts during spaceflight feel the hypergravity, psychological stress, fear, high doses of radiation and microgravity. All these factors and changes may affect immune system directly or indirectly.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
• /
• pp.223-228
• /
• 1997

In this study, bottom ash, lightweight aggregate, and Expanded Polystyrene was used to lighten the mortar. In order to compensate the reduction of strength caused by lightening, the waste foundry sand produced as solid waste was substituted for fine aggregate. As the device of reducing the ratio of absorption, the procedure of mixture was altered to check the effectiveness of surface coating of porous lightweight aggregate. It was observed over 170kg/$\textrm{cm}^2$ compressive strength at gravity about 1.3, an over 380kg/$\textrm{cm}^2$ at gravity about 1.7. the maximum strength was occurred when 30% of fine aggregate was replaced was replaced with waste foundry sand, and the ratio of absorption was decreased over 10% by changing the procedure of mixture.

• 한국학교수학회논문집
• /
• 제17권4호
• /
• pp.771-804
• /
• 2014

'무게중심'의 개념은 현재 초등교과영역에서 처음 등장하여 대학의 수학과 물리학, 공학 분야 등 폭넓게 응용되고 있지만 실제 교육은 실생활과 유리된 이론수업의 형태가 대부분이었다. 2013년 '${\bigcirc}{\bigcirc}$대학교 과학영재교육원'에서 영재학생들을 대상으로 '무게중심 확인 융합 프로그램'을 개발하였고, 본 연구에서는 이 프로그램을 수준별 수업으로 재구성하여 비영재학생들에게 적용시켜 그 효과성을 분석하고자 한다. 물체의 빈 공간이나 물체 밖에 무게중심이 존재하는 경우를 확인하는 실험 등 새로운 과정을 포함하였으며, 무게중심을 구할 때 핵심이 되는 지렛대의 원리에서 지렛대의 무게를 고려한 계산 방식을 제시하여 보다 실제적으로 개념에 다가갈 수 있도록 하였다. 초 중 고등학교 학생 총 65명을 대상으로 기존 8차시 프로그램을 4차시로 재편성하여 적용하였고, 수업 후 설문과 토론, 인터뷰 등을 통하여 분석한 결과, 학생들은 정밀한 오차분석 등의 과정을 통하여 수준 높은 성공의 경험을 하였다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
• /
• pp.190-195
• /
• 1997

The purpose of this study was to use daily waste incinerated ash, which was reclaimed worthlessly, as substitutes of fine aggregates in concrete. Various kinds of admixture was utilized to strengthen the cement mortar mixed with waste incinerated ash, and altered the curing condition to diminish the rate of expansion. By the results of this experiment, it was possible to produce the lightweight concrete, charactered with the gravity below 1.5 and over 160kg/$\textrm{cm}^2$ compressive strength by replacing all fine aggregates with waste incinerated ash. It was also observed that the low temperature curing condition, lessoned gas exhausts, was effective to increase the strength of cement mortar.

• 항공우주의학회지
• /
• 제28권1호
• /
• pp.6-8
• /
• 2018

It is essential to study the effects of hypergravity on the human body in the research field of aerospace medicine. Previous studies have shown that hypergravity could act in a harmful way to the human body. However, recent studies have shown that moderate degree of hypergravity can act in a beneficial way to the human body. The authors have in particular been studying the effects of hypergravity on immune diseases, especially allergic asthma and rhinitis. Therefore, this review paper will introduce the results of recent studies on hormetic (health promotion) effect of hypergravity. In addition, this review paper also examines the mechanism by which hormetic effect of hypergravity could be possible. Furthermore, we will also discuss how to apply these hormetic effects in clinical practice.

• Journal of Applied Biological Chemistry
• /
• 제49권4호
• /
• pp.148-153
• /
• 2006

While the underlying molecular mechanism remains to be elucidated, recent studies suggest that polar auxin transport is a key controlling factor in triggering differential growth responses to gravity. Identification of regulatory components in auxin-mediated differential cell expansion would improve our understanding of the gravitropic response. In this study, we identify a mutant designated aux1-like(later changed to aux1), an allele of the aux1 mutant that exhibits a severely disrupted root gravitropic response, but no defects in developmental processes. In Arabidopsis, AUX1 encodes an auxin influx carrier. Since in-depth characterization of the gravitropic response caused by mutations in this gene has been performed previously, we focused on identifying the downstream genes that were differentially expressed compared to wild-type plants. Consistent with the mutant phenotype, the transcription of the auxin-responsive genes IAA17 and GH3 were altered in aux1 plants treated with IAA, 2, 4-D and NAA. In addition, we identified two expansin genes EXP10 and EXPL3 that exhibited different expression in wild-type and mutant plants.

• Journal of Biosystems Engineering
• /
• 제41권3호
• /
• pp.177-183
• /
• 2016

Purpose: Mee (Madhuca longifolia) is an economically important tree growing throughout Sri Lanka. Its importance is mainly attributed to its oil with high nutritional and medicinal values. However, an inefficient extraction method limits its use. This study revealed the possibility of extracting oil from mee seeds by using a screw-type oil expeller. Methods: A popular screw-type oil expeller was used in the experiment. Extract bar clearance and speeds of the main spiral shaft were altered to increase the oil expelling efficiency of the machine. The quality of refined oil at the optimum oil yield was determined by measuring the refractive index, saponification value, iodine value, unsaponifiable matter, free fatty acid, and specific gravity. Results: An optimum yield of 35% oil was obtained when the machine capacity was 30 kg/h and energy consumption was 0.13 kWh/kg. This optimum machine condition was observed at an extract bar clearance of 0.5 mm and a main spiral shaft speed of 90 rpm. The refractive index, saponification value, iodine value, unsaponifiable matter, free fatty acid, and specific gravity of the oil were 1.4, 203, 59, 3.5%, 0.2%, and 0.907 g/cm3 respectively. Color of the mee oil was closer to yellow, which is revealed by the lightness value (L) of 24.93 and positive value (b) of 11.81. Conclusion: The screw-type oil expeller can be used for economically extracting mee oil on a commercial scale.

• The Korean Journal of Physiology and Pharmacology
• /
• 제11권1호
• /
• pp.1-7
• /
• 2007

Altered environmental gravity, including both hypo- and hypergravity, may result in space adaptation syndrome. To explore the characteristics of this adaptive plasticity, the expression of immediate early gene c-fos mRNA in the vestibular related tissues following an exposure to hypergravity stimulus was determined in rats. The animals were subjected to a force of 2 g (twice earth's gravity) for 1, 3, or 12 h, and were examined poststimulus at 0, 2, 6, 12, and 24 h. RT-PCR (reverse transcription polymerase chain reaction) and real-time quantitative RT-PCR were adopted to analyze temporal changes in the expression of c-fos mRNA. The hypergravity stimulus increased the expression of c-fos mRNA in the vestibular ganglion, medial vestibular nucleus, inferior vestibular nucleus, hippocampus, cerebellum, and cortex. The peak expression occurred at 0 h poststimulation in animals stimulated with hypergravity for 1 h, and at 6 h poststimulus in those stimulated for 3 h. In contrast, those stimulated for 12 h exhibited dual peaks at 0 and 12 h poststimulus. Bilateral labyrinthectomy markedly attenuated the degree of c-fos mRNA expression. Glutamate receptor antagonist also dramatically attenuated the degree of c-fos mRNA expression. These results indicate that expression of c-fos mRNA in response to hypergravity occurs in the vestibular related tissues of the central nervous system, in which peripheral vestibular receptors and glutamate receptors play an important role. The temporal pattern of c-fos mRNA expression depended on the duration of the hypergravity stimulus.

• 한국항공우주학회지
• /
• 제50권8호
• /
• pp.551-557
• /
• 2022

군용항공기는 노후화로 인해 LRU 개조가 필요한 경우가 많다. 최근 KA-O 공중통제기에 대해 사출좌석 교체 및 항공전자장비 추가 등 LRU 개조가 진행되면서 연료소비곡선 상의 항공기 운용 무게중심이 요구 사양 범위를 벗어나게 되었다. 이러한 범위를 벗어난 무게중심은 적절한 방법을 도입하여 수정해야 한다. 본 연구에서는 KA-O와 같은 군용 소형항공기의 LRU 개조로 인해 변경된 공허중량 무게중심을 수정하고 검증하는 절차를 제안한다. 제안하는 방법에서는 LRU 수정에 따른 공허중량 무게중심의 변화를 종합적으로 관찰한 뒤, 다수의 밸러스트를 엔진 설치대에 추가되어 연료소비곡선의 공허중량 무게중심을 안전한 작동 범위로 복원시킨다. 제안된 밸러스트 배치는 다양한 작동 조건에 대한 응력 및 피로해석을 통해 설치를 검증한다. 공허중량 무게중심 수정에 대한 공개 정보가 많지 않은 점을 고려할 때 본 연구는 항공기 개조 시 공허중량 무게중심을 수정하고 검증하기 위한 절차를 제시한다는 점에서 큰 의의가 있다고 사료된다.