• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.9 no.6
• /
• pp.117-122
• /
• 2006

The objective of this study is to analyze the greenroof runoff quantity and delay. The experimental districts, have different soil thickness and vegetation, had installed. A measurement was conducted in Seoul University to investigate the runoff quantity and delay of the greenroof. The measurement point of runoff quality data were 8, located next to each experimental district. Also, the precipitation was measured by rain gauges(# RG2). The experimental investigation lasted from 21th July to 4th December, a total of 137 days. The results showed that the greenroof can contribute runoff retention and delay by soil, but the intensity of actual rain event affected the runoff reduction and delay. Overall, when was the rainy season, percent rainfall retention ranged 17.5% and runoff flow was delayed for 1-3 hours. But on the other hand, when was the typical rain event, percent rainfall retention ranged over 90% and runoff flow was delayed for 1-11 hours. In the result, the greenroof had the greatest runoff retention and delay, while for the typical rain event.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.17 no.5
• /
• pp.468-476
• /
• 2005

The purpose of this study is to investigate actual air quality in newly-constructed multi-family houses and to improve Indoor Air Quality (IAQ). The field measurement was conducted in four different newly-constructed multi-family house complexes in Seoul and one existing multi-family house complex in Kyong-gi province. The result of the measurement shows that indoor concentrations of Formaldehyde and TVOC in newly-constructed multi-family houses are much higher than the foreign standards. To establish a proper process for reducing indoor air pollutants, various experiments have been conducted; application of natural materials, bake-out practice, closure of all openings without ventilation, and use of mechanical ventilation system. The result indicates that three practices (natural materials, bakeout, mechanical ventilation) can reduce the level of indoor air pollutants almost in half during the experiments. However, each practice has its limitation and is insufficient to satisfy IAQ standards. Therefore, the study proposes a proper reduction process of indoor air pollutants which combines four different practices in time sequence.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.17 no.12
• /
• pp.1184-1194
• /
• 2007

Recently, framed structure is increasingly being used as apartment structure due to the advantages during remodeling. Therefore, the use of lightweight panel as separating wall is increasing. To construct lightweight panel structures with sound insulation performance appropriate to the conditions of each field, measurement of sound reduction index(SRI) through panel structures should be performed. In this study, measurement of SRI through 46 kinds of panel structures was performed in the condition of various factors such as surface density, air space and absorber. The result showed that SRI of panel structures was generally higher by increasing of surface density. In the case of double panel with no absorber, SRI at below critical frequency was gradually increased according to rise of air space. Double panel with absorber make remarkable improvement in SRI at low frequency, but there is a little difference compared with SRI of double panel with no absorber over critical frequency.

• Journal of Korean Society for Geospatial Information Science
• /
• v.14 no.3 s.37
• /
• pp.31-37
• /
• 2006

The existing tunnel survey method contains many problems of taking much measuring time, increasing construction expenses, and delaying a term of construction. Therefore the site survey system for an improvement efficiency is developed. This system will be able to solve the ewer factor and the problem of curtailment of time and expenditure. In order to solve these problems it connected a measurement equipment and a notebook computer, and developed the system which simultaneously with tunnel measurement it will be able to decide locations and errors from site at real-time. The development or the tunnel survey system minimize the error occurrence as measuring tunnel, and the probability of more or less excavation. Therefore this site survey system leads to the effect of the improvement execution quality of work, the cost reduction and the construction term reduction.

• Journal of Biomedical Engineering Research
• /
• v.29 no.3
• /
• pp.239-248
• /
• 2008

In this study, a new method using a capacitive sensor and an adaptive filter was proposed to deal with artifacts contaminating an oscillation signal in oscilometric blood pressure measurement. The proposed method makes use of a variation of the capacitance between an electrode fixed to a cuff and an external object to detect artifacts caused by the external object bumping into the cuff. The proposed method utilizes the adaptive filter based on linear prediction to remove the detected artifacts. The conventional method using linear interpolation and the proposed method using the adaptive filter were applied to three types of the artifact-contaminated oscillation signals(no overlap, non-consecutive overlap, and consecutive overlap between artifacts and oscillations) to compare them in terms of the artifact reduction performance. The proposed method was more robust than the conventional method in the case of consecutive overlap between artifacts and oscillations. The proposed method could be useful for measuring blood pressure in such a noisy environment that the subject is being transported.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.12
• /
• pp.1689-1696
• /
• 2017

In this paper, the voltage measurement-based coordinated Voltage/VAR control (VMCVVC) algorithm for conservation voltage reduction(CVR) is proposed. The proposed algorithm has the purpose of enhancing the CVR effect through coordinated control of the voltage control devices such as the distributed energy resources and the load tap changer(LTC) transformers. It calculates the references of the voltage control devices such that the bus voltages are maintained at as close to the lower operation limit as possible. For this purpose, firstly, the distribution system is divided into LTC transformer control zones through topological search. Secondly, the reactive power references of the reactive power control devices are determined such that the voltage profile of the section is flattened. Finally, the tap references of the LTC transformers are calculated to lower the voltage profile. The effectiveness of the proposed algorithm is demonstrated through case studies using IEEE test network.

• Wind and Structures
• /
• v.18 no.3
• /
• pp.295-320
• /
• 2014

The characteristics of amplitudes and power spectra of X axial, Y axial, and RZ axial (i.e., body axis) wind forces on a 492 m high-rise building with a section varying along height in typical wind directions are studied via a rigid model wind tunnel test of pressure measurement. Then the corresponding mathematical expressions of power spectra of X axial (across-wind), Y axial (along-wind) and torsional wind forces in $315^{\circ}$ wind directions are proposed. The investigation shows that the mathematical expressions of wind force spectra of the main structure in across-wind and torsional directions can be constructed by the superimposition of an modified wind spectrum function and a peak function caused by turbulent flow and vortex shedding, respectively. While that in along-wind direction can only be constructed by the former and is similar to wind spectrum. Moreover, the fitted parameters of the wind load spectra of each measurement level of altitude are summarized, and the unified parametric results are obtained. The comparisons of the first three order generalized force spectra show that the proposed mathematical expressions accord with the experimental results well.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.33 no.6 s.113
• /
• pp.1-11
• /
• 2006

The purpose of this study was to investigate the influence of natural landscapes in the context of work environments. The study examined the impact of natural landscapes on urban office workers' stress reduction and cognitive performance, using physiological, psychological, and cognitive measures. One-hundred-twenty urban office workers participated in the experiments. The physiological measures used were GSR (galvanic skin response) and IBI (interbeat interval), and the psychological measure was ZIPERS (Zucherman Inventory of Personal Reactions). Cognitive performance was measured using a mental arithmetic test that had been developed by a pretest. The results from the physiological, psychological, and cognitive measures converged to indicate that the natural landscape had more beneficial effects in relieving both psychological and physiological stress and in enhancing cognitive performance of the of office workers than the city landscape. The results suggest wide applications in the fields of workers' well-being and landscape research. First, the results can provide reliable information for promoting natural landscaping in work places in order to relieve worker stress and enhance cognitive performance. Second, the results provide an example for future empirical landscape research using multiple measurements, such as psychological, physiological, and cognitive tests. Third, they can foster experimental research to investigate the relationship between stress reduction and natural landscapes.

• Structural Engineering and Mechanics
• /
• v.30 no.4
• /
• pp.445-466
• /
• 2008

This paper presents a novel structural damage detection method with a new damage index based on the statistical moments of dynamic responses of a structure under a random excitation. After a brief introduction to statistical moment theory, the principle of the new method is put forward in terms of a single-degree-of-freedom (SDOF) system. The sensitivity of statistical moment to structural damage is discussed for various types of structural responses and different orders of statistical moment. The formulae for statistical moment-based damage detection are derived. The effect of measurement noise on damage detection is ascertained. The new damage index and the proposed statistical moment-based damage detection method are then extended to multi-degree-of-freedom (MDOF) systems with resort to the leastsquares method. As numerical studies, the proposed method is applied to both single and multi-story shear buildings. Numerical results show that the fourth-order statistical moment of story drifts is a more sensitive indicator to structural stiffness reduction than the natural frequencies, the second order moment of story drift, and the fourth-order moments of velocity and acceleration responses of the shear building. The fourth-order statistical moment of story drifts can be used to accurately identify both location and severity of structural stiffness reduction of the shear building. Furthermore, a significant advantage of the proposed damage detection method lies in that it is insensitive to measurement noise.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.2 s.25
• /
• pp.11-19
• /
• 2006

The underwater electromagnetic signatures of a naval ship are mainly generated from three sources which are the permanent and induced magnetic field in the ship's hull and other ferrous components, the cathodic current electromagnetic field established by the Impressed Current Cathodic Protection(ICCP) system or the Sacrificial Anode and the stray electromagnetic fields generated by onboard equipment. These signatures can be minimized by certain design methods or installation of signature reduction equipment. In this paper, we represented the characteristic of the underwater electromagnetic signature and the signature reduction techniques for a naval ship. Also, we measured the electromagnetic field changes emitted from the real ship using the Electric and Magnetic field Measurement System(EMMS). We found that the underwater electromagnetic signature for a naval ship can be used as input or trigger signal in a surveillance system and an influence mine.