• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.760-761
• /
• 2011

Ground differential relay is used to provide fast, sensitive, and selective protection for the wye connected and grounded electrical power equipment such as generators, power transformers, and grounding transformers. The ground differential protection only protects the ground faults within the protection zone, so that it can't protect the line-to-line fault. This paper proposes the algorithm to provide the protection for the line-to-line fault through the ground differential protection. The proposed algorithm detects the line-to-line fault of transformer using the comparison between the positive and the negative current, when the ground differential relay dose not operate. The performance of the algorithm is verified using a PSCAD/EMTDC simulator under various case studies.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2005년도 춘계학술대회 논문집
• /
• pp.722-725
• /
• 2005

Recently, ground-borne noise and vibration generated by underground transit system has been recognized as an important environmental problem. This study reviews several of the improved procedures that have been used to predict ground-borne vibration. At first, ground stiffness profile is examined by SASW test which is the most reasonable surface wave test. It is very important to acquire the exact ground stiffness profile at ground response analysis. At second, the train loading to act roadbed is calculated by using the real measured phase angle data. In finite element analysis, averaged acceleration method, infinite element, Rayleigh damping and 2-dimensional wave propagation analysis is performed.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.1453-1454
• /
• 2007

A street light is an electrical equipment to improve the traffic safety and the security for people in night. However, many accidents due to electric shock have happened in recent, people were interested in the safety of electrical facilities. And people want to know the danger by touch and step voltages. When the electric power lines fall down on the ground, the fault current flows to ground rod and the potential near the ground rod is increased to induce the high touch and step voltages. In this paper, we installed different ground rods with a street light and investigated the electrical potential according to ground methods and the types of ground rod. Finally, we examined the electrical facilities with the experimental result and present the improved technical data for the safety from electric shock

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
• /
• pp.1058-1060
• /
• 2003

A ground control point (GCP) is a point on the surface of Earth where image coord inates and map coordinates can be identified. The GCP is useful for the geometric correction of systematic and unsystematic errors usually contained in a remotely sensed data. Especially in case of synthetic aperture radar (SAR) data, it has serious geometric distortions caused by inherent side looking geometry. In addition, SAR images are usually severely corrupted by speckle noises so that it is difficult to identify ground control points. We developed a ground point extraction algorithm that has an improved capability. An application of radargrammetry to Daejon area in Korea was studied to acquire the geometric information. For the ground control point extraction algorithm, an ERS SAR data with precise Delft orbit information and rough digital elevation model (DEM) were used. We analyze the accuracy of the results from our algorithm by using digital map and GPS survey data.

• 한국지반공학회논문집
• /
• 제21권5호
• /
• pp.45-50
• /
• 2005

최근에 샌드드레인공법이나 샌드콤팩션파일공법 등과 같이 모래말뚝을 이용한 연약점토지반 개량공법의 적용이 증가하고 있다. 이러한 공법들로 개량된 연약점토지반에서는 모래말뚝에 의한 압밀촉진효과를 기대 할 수 있는데 실무에서는 보통 Barren의 이론해 등과 같은 이론식을 이용하여 그 효과를 평가하고 있다. 그러나 이러한 이론식들은 복합지반의 비선형 체적압축거동과 압밀중의 투수계수 변화 현상을 고려할 수 없으며, 따라서 그 평가결과가 합리적 이라고 판단하기 힘들다. 본 연구에서는 일련의 수치해석을 실시하여 Barren의 이론해에 적용되는 복합지반의 압밀정수 결정법에 대하여 고찰하였다. 수치해석 결과의 분석을 통하여 압밀 중에 변화하는 점토부의 체적압축거동특성과 투수성의 변화특성을 고려한 압밀정수의 결정방법을 제안하였다.

• 한국지반공학회논문집
• /
• 제24권6호
• /
• pp.95-100
• /
• 2008

판상의 연직배수재를 이용한 연약지반개량공법에 대한 설계를 보다 정확하게 수행하기 위해서는 판상 배수재의 유효 등가경 결정이 매우 중요한 요소이다. 본 연구에서는 연약지반의 압밀거동을 고려한 합리적인 판상 배수재의 유효 등가경 결정방법에 대한 고찰을 위하여 일련의 수치해석을 실시하였다. 본 연구에서 사용한 탄점소성 3차원압밀 유한요소해석 방법은 동일한 조건의 실내모형실험 결과와의 비교를 통하여 검증하였다. 또한, 수치해석 결과로부터 판상 연직배수재로 개량된 연약지반의 압밀거동을 재현하였으며, 이를 반영한 판상 연직배수재의 유효 등가경을 산정하였다.

• 한국측량학회:학술대회논문집
• /
• 한국측량학회 2006년도 춘계학술발표회 논문집
• /
• pp.469-473
• /
• 2006

In general, a classification process between ground data and non-ground data, which include building objects, is required prior to producing a DEM for a certain surface reconstruction from LiDAR data in which the DEM can be produced from the ground data, and certain objects like buildings can be reconstructed using non-ground data. Thus, an exact classification between ground and non-ground data from LiDAR data is the most important factor in the ground reconstruction process using LiDAR data. In particular, building objects can be largely used as digital maps, orthophotos, and urban planning regarding the object in the ground and become an essential to providing three dimensional information for certain urban areas. In this study, an entropy theory, which has been used as a standard of disorder or uncertainty for data used in the information theory, is used to apply a more objective and generalized method in the recognition and segmentation of buildings from raw LiDAR data. In particular, a method that directly uses the raw LiDAR data, which is a type of point shape vector data, without any changes, to a type of normal lattices was proposed, and the existing algorithm that segments LiDAR data into ground and non-ground data as a binarization manner was improved. In addition, this study proposes a generalized building extraction method that excludes precedent information for buildings and topographies and subsidiary materials, which have different data sources.

• 한국환경복원기술학회지
• /
• 제4권4호
• /
• pp.12-18
• /
• 2001

This study was carried out to analyze physico-chemical properties of soils at the ground of landscape planting in reclaimed land from the sea on Kwangyang Bay, South Korea. Physico-chemical properties of soils at each planting grounds were tested by ANOVA and were significantly(P<0.01) different. The difference came from the soil properties of the covered soil, the disturbance applied to the soil with land use and the accumulation of organic matter after landscape planting. Soil hardness, pH, ECe, Na and K level were in a stable condition at high then low of ground height for landscape planting. Organic matter accumulation was greater at lower planting grounds then top and slope ground of big mounding. The planting grounds of favorable growth for landscape trees were determined as following order : the slope ground and the top ground of big mounding>the ground of medium mounding>the coved ground of improve soil>the lower ground of big mounding>the filled ground of improve soil.

• Journal of Astronomy and Space Sciences
• /
• 제24권4호
• /
• pp.389-396
• /
• 2007

The Global Navigation Satellite System (GNSS) becomes more important and is applied to various systems. Recently, the Galileo navigation system is being developed in Europe. Also, other countries like China, Japan and India are developing the global/regional navigation satellite system. As various global/regional navigation satellite systems are used, the navigation ground system gets more important for using the navigation system reasonably and efficiently. According to this trend, the technology of GNSS Ground Station (GGS) is developing in many fields. The one of purposes for this study is to develop the high precision receiver for GNSS sensor station and to provide ground infrastructure for better performance services on navigation system. In this study, we consider the configuration of GNSS Ground Station and analyze function of Monitoring and Control subsystem which is a part of GNSS Ground Station. We propose Monitoring and Control subsystem which contains the navigation software for GNSS Ground System to monitor and control equipments in GNSS Ground Station, to spread the applied field of navigation system, and to provide improved navigation information to user.

• 한국지반신소재학회논문집
• /
• 제8권3호
• /
• pp.9-16
• /
• 2009

최근 우리나라에서 활발히 진행되고 있는 준설매립 공사에서는 일반적으로 시공 장비의 주행성을 확보하기 위한 표층처리공법으로써 지오텍스타일을 부설하는 경우가 많다. 지오텍스타일이 부설된 초연약점토지반의 지지력의 계산은 기존에 몇 가지 제안되어 있지만 아직 명확히 확립되어있지 않기 때문에 시공실적에 기초한 경험적인 방법이 사용되고 있는 실정이다. 본 논문에서는 지오텍스타일이 부설된 초연약지반의 합리적인 지지력 산정방법 확립의 일환으로 일련의 수치해석을 실시하였다. 수치해석결과 초연약지반의 표층을 지오텍스타일로 보강함으로써 초연약지반의 항복 후에도 개량된 지반의 지반응력은 증가함을 알 수 있었으며 지요텍스타일에서 발생되는 최대인장응력은 하중이 증가함에 따라 재하 끝단부에서 크게 발생됨을 알 수 있었다.