• Journal of Korean Society of Forest Science
• /
• v.59 no.1
• /
• pp.15-30
• /
• 1983

To select the superior clones of Populus alba ${\times}$ Populus glandulosa $F_1$, growth and some growth-related physiological characters were examined for thirteen, one-year-old and fifteen, two-year-old clones, respectively at the Seoul National University nursery in Suweon, Clonal differences in growth (total dry weight per tree), leaf area per tree and leaf chlorophyll content per tree at tow-year-old plots were highly significant at the 1% level, but not at one-year-old plots, Highly significant correlation was found between leaf area per tree and total dry weigh per tree (r=0.865), between leaf chlorophyll content per tree and total dry weight per tree (r=0.888), and between photosynthetic ability per tree and total dry weight per tree (r=0.745). The photosynthetic ability and leaf chlorophyll content per unit leaf area of one-year-old plant increased with increasing leaf order number from top. reached maximum value in the twenty-eithth and thirty-third leaves, respectively, and then decreased gradually from those leaved to base, Clones 68-1-54, 66-26-55 and 65-22-11 showed test growth based on leaf area per tree, leaf chlorophyll content per unit leaf area and photosynthetic ability of leaf tissue per unit area. Growth yield of populus alba ${\times}$ P. glandulosa $F_1$ clones could be estimated from either leaf area per tree of leaf chlorophyll content per tree. Therefore, measurements of leaf area and leaf chlorophyll content appear useful to select superior populus clones early growth.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.65.2-65.2
• /
• 2010

Currently the variety of governmental business support and research for supplying solar energy have been actively progressed. As of now, however, There are no practical testing infrastructures of grid-connected photovoltaic system which test performance of solar power facility in domestic. Therefore, in KEPRI, there is in progress construction of practical testing ground of 500 kW class grid-connected PV System for developing the evaluation of the performance technology including the Module, PCS, and etc, that is the important instrument of the PV System, in Gochang area. It analyzed the site creation work for constructing the practical testing ground and new construction of control room and the unit standards, specifications and capacity of required equipment. For the system detailed design, configuration, instrument-specific parameters established, power generation predictions of Array Type and the components of testing ground are needed to build.

• Steel and Composite Structures
• /
• v.36 no.6
• /
• pp.657-669
• /
• 2020

This study investigates the fire resistance characteristics of reactive powder concrete according to changes in the cement content per unit area, mixing ratio of metakaolin (MK), and content of polypropylene fiber. A fire test was conducted, and the resulting residual strength characteristics were investigated through flexural and compressive strength measurements, as well as condition rating classification based on visual evaluation. MK effectively reduced the initial high content of calcium hydroxide, thereby reducing the water vapor pressure generated during pyrolysis and slowing spalling. Furthermore, the pore structure and loose tissue were effective for relieving the water vapor pressure in the event of a fire.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.9
• /
• pp.853-859
• /
• 2000

In this study, low temperature waste heat recovery heat exchanger was developed using a principle of self-excited oscillating heat pipe. The heat exchanger of serpentine type was composed of extruded flat aluminum tube with 6 channels (3 nm$\times$ 2.75nm) and louvered fin. The heat transfer area density of heat exchanger was $331.9 m^2/m^3$. Working fluid is R141b and charge ratio was 40% by volume. Heat transfer rate and the effectiveness of heat exchanger was primary concern of this study. As a result, the effectiveness of heat exchanger was about 0.4-0.67, and recovered waste heat rate was about 4.5 kW per one unit of heat exchanger.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.03b
• /
• pp.309-316
• /
• 2000

When highly compressible, clayey soil layers lies at a limited depth and large consolidtion settlements are expected as the result of construction, precompression of soil may be used to minimize postconstruction settlement. In this study, we tried to find the possibility about the effect of ground improvement using flat dilatometer at the Inchon International Airport where preloading was installed. Field and laboratory tests were performed for soft ground before and after preloading in order to check the effectiveness of the soft ground improvement and compared with the test results of dilatometer which obtained before and after preloading at the same location Field tests such as flat dilatometer, vane, CPTu tests were performed before and after preloading and undisturbed samples are obtained to carry out laboratory tests. As comparing results, after preloading, unit weight, effective stress, undrained shear strength were increased and we can also check the decrease of consolidation late caused of decrease of void ratio. Furthermore, it is assumed that the possibility on the effect of ground improvement by using the flat dilatometer

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.1258-1263
• /
• 2004

The present study proposes a new structure for a heat spreader which could embody a thin thickness, any shapes and high heat flux per unit area. It is on the structure for the formation of vapor passages and the support of the case of the heat spreader. A screen mesh is used as the one. To verify the validity of the one, the heat spreader of 1.4mm and 1.6mm thickness was made with 14 mesh and 100 mesh number. In this paper, The performance test of heat spreader conducted in order to compare with the heat transfer performance of conventional heat pipe. As the results, The heat spreader has excellent cooling and heat transfer performance.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.5
• /
• pp.92-98
• /
• 2003

A wind turbine monitoring system is essential equipment fur the performance evaluation and mechanical load analysis of a wind turbine. A monitoring system using LabVIEW is developed in this study. This system monitors signals from a meteorological mast, wind turbine generator, and tower. The discrete signals which are sampled at t Hz are automatically saved on a data file in the unit of a day. Besides these basic functions, the developed monitoring system has the other several capabilities. One of them is the information access from a remote PC through the internet. A vision image of the test site area and data files that are produced by LabVIBW software can be uploaded to the main computer located in a remote site. An emergency backup system using UPS fur the power loss on the monitoring HW is also prepared, A detail explanation for the developed wind turbine monitoring system is presented in this study.

• ETRI Journal
• /
• v.35 no.6
• /
• pp.1048-1057
• /
• 2013

In recent years, augmented reality (AR) technologies have been the subject of great interest among many communities. In education applications, old-fashioned materials (or textbooks) are still used, despite remarkable AR developments in the industrial area. We present an AR system for education. Our system consists of an authoring tool that can be used to create educational content, a viewer that plays that content, and an engine to manage the tool and viewer. In our system, a marker unit recognizes a marker printed on a plane or a cubic plane by adaptively adjusting the threshold to have an excellent recognition rate in diverse environments and acquires corresponding data of the marker. Based on the system, we test 142 elementary school students for increased educational benefits using our system.

• Journal of Korean Academy of Nursing
• /
• v.14 no.2
• /
• pp.5-11
• /
• 1984

The main purpose of this study were; to determine the reliability and validity of evaluation tool administered to the nursing student in nursing management practice,；to identify the effective evaluation method of nursing student in nursing management practice. The subjects were 46 senior nursing students at Department of Nursing, College of Medicine, Seoul National University in 1983. The evaluation tool was analyzed according to evaluation method; self-evaluation. and head nurse evaluation. Also individual item of evaluation tool was analyzed by item analysis in order to determine the evaluation area, and appropriateness of the test item used. A Summary of the results is as follows; 1. The reliability and validity of evaluation tool were relatively high both in self-evaluation and head nurse evaluation. 2. In comparison of mean scores, there is no significant difference between head nurse evaluation and self-evaluation. 3. The nursing management activities which have the correlation of self-evaluation and head nurse evaluation were in the activity of interpersonal relation, independent activity and implementing nursing process. In general nursing practice and unit management activity, there was no correlation of self-evaluation and head nurse evaluation.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.1331-1332
• /
• 2015

본 논문은 CAN(Controller Area Network) 통신의 WCRT(Worst Case Response Time) 분석을 통해 IEEE1212 기반 RTU(Remote Terminal Unit)의 통신 신뢰성을 검증한다. RTU는 원격지에서 네트워크를 구성하여 각 모듈들로부터 획득한 정보를 서버로 전송하거나 원격지를 제어하는 역할을 한다. 본 논문에서 대상으로 하는 RTU의 네트워크는 물리계층과 데이터링크 계층은 CAN을 사용하고 응용계층은 IEEE1212 기반으로 통신한다. 즉, RTU를 구성하는 모듈은 각각메모리 영역을 가지고 있고, CAN ID에 메모리 주소를 포함하여 해당 영역을 쓰는 구조로 통신을 한다. 첫 번째로 이러한 응용계층을 고려하여 WCRT를 계산하는 방법을 제시하고, 두 번째로 CAN 메시지의 우선 순위를 최적화하는 방법을 고찰한다. 마지막으로 시험 환경을 구축하고 시뮬레이션을 통해 앞에서 선정한 우선순위에 따라 통신 신뢰성을 검증한다.