In fisheries, the importance of designing efficient fish cages is being emphasized as aquaculture has become more production than capture fishing. Particularly, the gravity cage system is one of the popular fish cage system in Korea. Currently, gravity cages of various shapes and sizes are being widely designed and installed in offshore and inland seas. The cage is subject to external forces, such as currents and waves, and the shape of the structure and tension on the ropes changes according to these external forces. Thus, it is important to accurately calculate these dynamic behavior, including the external forces and tension on the structure during the design stage. In this study, three types of cage systems with an equal internal volume of 8000 m3 were analyzed using mass-spring models and their behavior was interpreted through simulations. These simulations were used to analyze the behavior and tension of the ropes in response to currents and waves to aid in the selection of individual cage sizes for a given total volume. The numerical calculation results indicate that depending on the flow rate, the most resistant system is System 1, which has eight strays, and System 2 and System 3 have 69.4% and 54.8% of the resistance of System 1. Further, total resistance increased as the number of cages increased for all flow rates.

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).

본 연구는 기장 종자의 발아활력 증진과 입모 균일성을 통한 안정적인 생산을 위해 염수선(비중) 종자정선을 활용한 통한 발아율, 유모의 소질 및 포장 출현율을 알아보고자 수행하였다. 1. 염수선에 따른 기장은 비중이 높아질수록 천립중이 증가 하였으며, 표준발아에서는 정선 종자에서 3품종 모두 91% 이상 발아율을 보였으며, 비중선 1.040 g l-1에서 ‘황금’ 98.9%, ‘이백찰’ 99.4%, ‘황실찰’ 98.9%로 가장 높았다. 2. 모 소질을 조사한 결과 초장에서는 비정선 종자에 비해, 정선된 종자에서 평균 초장은 2.0, 2.2 및 1.9 cm 길었고, 엽장에서는 ‘황금’과 ‘이백찰’에서만 유의성이 있었으며, 경직경과 SPAD에서는 염수선 비중에 따른 유의성이 보이지 않았다. 3. 염수선에 정선된 종자의 평균 근장, 근중 및 경중 모두 길거나 무거웠으며, 근장에서는 1.040 g l-1에서 비정선 종자에 비해 2.9, 3.0 및 2.9 cm 길게 나타났고, 근중과 경중에서도 1.040 g l-1에서 가장 무겁게 조사되었다. 4. 포장 발아활력 검정에서는 품종에 따라 평균출아일수에서만 유의성이 있었으며, 염수선 처리에서는 출아율 및 출아율지수에서 고도의 유의성이 나타났다. 3품종 모두 비중선이 높을수록 출아율과 출아율지수가 증가하였고, 비중선 1.040 g l-1 에서 가장 높은 90.7, 85.3 및 92.8% 출아율이 나타났다. 5. 기장의 출아율 증진과 입모 균일성 향상을 통한 생산성 증대를 위해서는 염수선을 통해 비중선 1.040 g l-1에서의 종자를 선별이 유리한 것으로 사료된다.

The curvature of spacetime represented by Einstein field equation has many physical implications, including gravity. As light is deflected by the curvature of spacetime, a magnetic field will also be influenced by the curved spacetime. A permanent magnet is generally known to maintain its persistent magnetic field on the ground as long as there is no external magnetic interference. However, a series of experiments find that there are noticeable changes in the magnetic fields distribution while the permanent magnet rotates. The magnetic field lines of the permanent magnet are deflected towards Earth’s centre, implying a possibility that we can use magnetic field, a more efficient tool than a satellite, to measure the curvature of spacetime. However, comparing the experimental results of this study with theoretically obtained values of the curvature of spacetime remains a vast area of research for future studies.

This paper presents the theoretical analysis for the flow driven by surface tension and gravity force in an inclined circular tube. The previously developing equation for Power-Law model is a simple ordinary differential type. A governing equation is developed for describing the displacement of a non-Newtonian fluid(Casson model) that continuously flows into a circular tube by surface tension, which represents a second-order, nonlinear, non-homogeneous, and ordinary differential form. It was found that the theoretical predictions of the governing equation were in good agreement with the results for considering the Newtonian model.

A Gravity-driven membrane (GDM) system is one of the promising solutions for household drinking water treatment in the developing countries. In this study, the GDM system was tested for optimizing manual cleaning protocols using three different feed water solutions. Two types of manual cleaning were performed to delay the permeability decrease, cleaning between batches and long-term cleaning. The optimized cleaning between batches protocol was 3 twisting and 10 vertical shaking. And the optimized long-term cleaning protocol was 70 vertical shaking for both the middle region of the module and near the header part. These cleaning protocols allowed the system to produce sufficient water to meet the daily minimum water requirements for a 5-person family, even for using the wastewater influent. The system produced Escherichia coli free water.

Pseudo-static approach has been conventionally applied for the design of gravity type quay walls. In this method, seismic coefficient (kh), expressed in terms of acceleration due to gravity, is used to convert the real dynamic behavior to an equivalent pseudo-static inertial force for seismic analysis and design. Therefore, the calculation of an appropriate kh considering frequency characteristics of input earthquake is critical for representing the real dynamic behavior. However, the definitions of kh, which is used for simplified analysis in Korea, focuses only on convenience that is easy to use, and the frequency characteristics of input earthquake are not reflected in the kh definitions. This paper evaluates the influences of the frequency characteristics of input earthquake on kh by initially reviewing the kh definitions in the existing codes of Japan for port structures and then by performing a series of dynamic centrifuge tests on caisson gravity quay walls of different earthquake input motions (Ofunato, Hachinohe). A review of the existing codes and guidelines has shown that the kh values are differently estimated according to the frequency characteristics of input earthquake. On the other hand, based on the centrifuge tests, it was found that the permanent displacements of wall are more induced when long-period-dominant earthquake is applied.

The present study was carried out to deduce optimum harvesting time based on fruit traits that were examined with fruits hanging the higher part (HP, higher than or equal to 2m height from the ground) and lower part (LP, lower than or equal to 1.5m height from the ground) on ‘Niitaka’ tree. The fruits of HP compared to of LP tended to be heavy and showed significantly higher soluble solid contents (SSC), hardness and gravity at each of the harvest time. On the basis f the discrepancies of the fruit traits between HP and LP, harvest time for the fruits of LP are acquired to be delayed for raising fruit weight and SSC. Due to the substantial probability of flesh pithiness based on the dramatic decrease of fruit gravity, it is necessary that the fruits of LP distributed just after harvesting or stored for short-term period.

한 개 측선에서 얻어진 중력 변화율 텐서 자료를 이용하여 주향과 경사를 가지는 선형 이상체의 위치를 결정하 는 알고리즘을 제시하였다. 기존에 연구된 중력 변화율 텐서를 이용한 선형 이상체의 주향과 경사를 결정하는 방법을 발전시켜서, 선형 이상체의 주향과 경사를 결정한 이후 이상체의 위치를 결정하는 알고리즘을 개발하였다. 선형 이상체 의 주향과 경사는 2차원 이상체로부터 얻어지는 중력 변화율 텐서가 회전 변환 후 2개의 독립 성분만을 가진다는 특징 을 이용하여, 중력 변화율 텐서의 5개의 독립 성분을 2개의 독립 성분으로 축소시키는 회전 변환 각으로부터 선형 이 상체의 주향과 경사를 결정한다. 이상체의 위치를 가리키는 방향 벡터는 중력 변화율 텐서의 회전변환 후 남은 2개 독 립 성분의 비를 이용하여 유도하였다. 여러 측점에서 계산된 이상체를 가리키는 방향 벡터가 수렴하는 영역이 선형 이 상체의 위치로 결정된다. 최소자승법을 이용하여

Pseudo-static approach has been conventionally applied for the design of gravity quay walls. In this method, the decision to select an appropriate seismic coefficient (kh) is an important one, since kh is a key variable for computing an equivalent pseudo-static inertia force. Nonetheless, there is no unified standard for defining kh. Likewise, port structure designers in Korea have a difficulty in choosing an appropriate kh definition, as there are conflicts in how kh is defined between the existing seismic code of port structures and the proposed new one. In this research, various seismic design codes for port structures were analyzed to compare the definitions of the seismic coefficient. The results were used for the proposing a unified seismic coefficient definition. Further, two dynamic centrifuge tests were performed with different wall heights (5 m, 15 m) to clarify the reference point of peak acceleration used in determination of kh according to the wall height. Results from dynamic centrifuge experiments showed that correction factors for the peak ground acceleration considering both the wall height and allowable displacement are needed to calculate kh.

본 연구에서는 세굴된 해저 파이프 주위 중력류의 유동 해석을 수행하였다. 결과 비교를 위해 세굴이 아닌 평평한 해저면 위에 틈새 거리를 두고 설치된 해저 파이프 문제를 함께 고려하였다. 여기서 세굴의 깊이와 틈새 거리는 동일하며, 평평한 해저면 위에 설치된 파이프 문제는 일반적으로 실제 세굴효과를 이상적으로 구현하기 위해 주로 고려된다. 중력류와 해저 파이프 상호작용에 대한 유동특성의 이해를 위해 농도 및 와도장, 압력장 그리고 양항력 계수 등, 다양한 물리량들을 비교 및 분석 하였다. 결과적으로 세굴과 평평한 해저면 위에 설치된 해저 파이프 주위 유동특성이 달라짐을 관찰하였다, 특히 세굴의 위 파이프의 경우 구조물 상부에서 발달된 음의 와만 하류로 나아가게 되지만 평탄면 위 파이프는 이열 와구조 형태를 가지는 것을 확인하였다. 따라서 중력류에 놓인 해저 파이프의 안전 설계를 위해서는 무엇보다 실제 세굴조건을 고려하는 것이 중요 할 것으로 판단된다.

PURPOSES : The aim of this study was to compare the performance of the QUEENSOD method and the gravity model in estimating Origin-Destination (O/D) tables for a large-sized microscopic traffic simulation network. METHODS : In this study, an expressway network was simulated using the microscopic traffic simulation model, VISSIM. The gravity model and QUEENSOD method were used to estimate the O/D pairs between internal and between external zones. RESULTS: After obtaining estimations of the O/D table by using both the gravity model and the QUEENSOD method, the value of the root mean square error (RMSE) for O/D pairs between internal zones were compared. For the gravity model and the QUEENSOD method, the RMSE obtained were 386.0 and 241.2, respectively. The O/D tables estimated using both methods were then entered into the VISSIM networks and calibrated with measured travel time. The resulting estimated travel times were then compared. For the gravity model and the QUEENSOD method, the estimated travel times showed 1.16% and 0.45% deviation from the surveyed travel time, respectively. CONCLUSIONS : In building a large-sized microscopic traffic simulation network, an O/D matrix is essential in order to produce reliable analysis results. When link counts from diverse ITS facilities are available, the QUEENSOD method outperforms the gravity model.

Massive gravity provides a natural solution for the dark energy problem of cosmology and is also a candidate for resolving the dark matter problem. I demonstrate that, assuming reasonable scaling relations, massive gravity can provide for Milgrom’s law of gravity (or “modified Newtonian dynamics”) which is known to remove the need for particle dark matter from galactic dynamics. Milgrom’s law comes with a characteristic acceleration, Milgrom’s constant, which is observationally constrained to a0 ≈ 1.1×10−10ms−2. In the derivation presented here, this constant arises naturally from the cosmologically required mass of gravitons like a0 ∝ c√ ∝ cH0√3 , with , H0, and  being the cosmological constant, the Hubble constant, and the third cosmological parameter, respectively. My derivation suggests that massive gravity could be the mechanism behind both, dark matter and dark energy.

Prestressed concrete PSC girders are efficient in terms of structural performance, economical efficiency and constructability. However, PSC girders have overtuning risk in construction in which extra work needs to protect. The low center of gravity girder (MPC girder) is more stable and easier to construct than the traditional PSC girder, which has tweaked end point and mono-tendon anchor. In this study, we evaluated the structural advantages in the deflection (slope) and stress on the link slab by using the finite element method. As a result, it was found that the reinforcement in the link slab for the bridge continuation may be reduced because of less displacement.