• Journal of the Optical Society of Korea
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• v.18 no.3
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• pp.244-250
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• 2014

Due to the difficulty in measuring very low out-of-band cutoff depths of solar blind UV filters, we propose a cutoff depth adjustable measurement system (CDAM) to test deep cutoff filters with a large dynamic range. The CDAM utilizing the substitution method is elaborately composed of several parts, including narrow-band LED light sources, standard reflective neutral attenuators with known attenuation coefficients, and a photomultiplier (PMT). This paper also presents an attenuator combination method ensuring that the PMT works within its linear response range. In addition, numerical simulation testifies to the method, and experiment shows that the CDAM system can achieve an extension of dynamic range from 0-6 OD to 0-10 OD, which is sufficient for the measurement of out-of-band cutoff depths of solar blind UV filters. Above all, the CDAM system, being easily implemented, of wide dynamic range, and highly precise, could be widely used in the measurement of filter cutoff depth.

• KIEAE Journal
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• v.11 no.2
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• pp.105-111
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• 2011

Aims of this study is to investigate the daylighting control strategy of venetian blind system was performed as a function of ratio of shading height to window and slat angles in the preliminary stage of the parametric study. Floor-to-ceiling window walls of living spaces are used widely in apartment buildings since the Korean government has legally allowed elimination of the balcony area. Enlarging living area by balcony elimination, the larger glass area of window is exposed to the direct sunlight. As a common sunlight controlling device, blind system can be used in all orientations and all latitudes and it may obstruct, absorb, reflect and transmit solar radiation to building by proper adjusting. However, blind system can produce discomfort in occupant and less energy efficiency, if it has not been controlled optimally. The simulation model was based on the unit module of typical living space with balcony elimination. The room dimension was $6.0m(w){\times}6.9m(d){\times}2.7m(h)$ with floor to ceiling height of 2.5m. The blind system was simulated at five slat angles (horizontal, $30^{\circ}$, $45^{\circ}$ upward and downward tilted) and the four ratio of shading height to window (fully closed, partly opened, no-blind) using the Desktop RADIANCE 2.0 program. The series of simulation results indicates that the advantages of available daylight and outside of view can be improved by proper adjusting blind system.

• Journal of the Korean Solar Energy Society
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• v.33 no.1
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• pp.89-95
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• 2013

A DBLP(Double blind light pipe) daylight system can be installed at a building exterior wall or roof to replace artificial light during the day time. This system was consisted of a double blind light collector, a mirror duct type light transformer and a prism light pipe distributor. The double blinds were used to track the sun's altitude and azimuth movements to collect the sunlight throughout the day. The sunlight collected by the light collector was reflected on the first mirror and the second mirror and sent to the light pipe through the light transformer. The transformer was designed to deliver the sunlight into the light pipe efficiently. The light distributor plays a role in diffusing the sunlight coming in through the light collector to be used for indoor lighting. In this paper, a DBLP system has been designed, installed and tested at a KIER daylighting twin test cell. The DBLP daylighting system was applied to the experimental test cell which has an indoor area of 2.0 m wide ${\times}$ 2.4 m height ${\times}$ 3.8 m length. The experiment was conducted from January 30 to February 27, 2012, under clear skies and partially cloudy skies. Data was collected from 10:00 am to 16:00 pm every 2 minute and the average was calculated for every 30 minute of the data collection to obtain the system efficiency. The results indicated that the DBLP system efficiency was evaluated as 11.67%. The DBLP system indoor illumination energy reduction was predicted as 0.822 kWh/day. This could replace 4 sets of a 32W fluorescent lamp operating 6.4 hours per a day.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.74-79
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• 2011

Concentration characteristics of the KIER solar furnace are analyzed with a heat flux measurement technique. Total heat capacity of 40kW was confirmed within 1.04% average error, and the normalized maximum heat flux of 3,452 $kW/m^2$ was proved. Non-Gaussian flux distribution in the vertical direction implies that reflectors should not be random rather inclined downwards. Moreover, we characterized flux distribution variations with furnace blind opening ratio, distance from the focal plane, and misalignment of the measurement system. Based on the results, the heat flux distribution can be simply estimated once reflectivity and direct normal insolation values are known. This study will be helpful to the design and the performance evaluation of receivers or chemical reactors.

• KIEAE Journal
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• v.7 no.1
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• pp.23-31
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• 2007

This study aims to evaluate the illuminance performance of sloped light guide with automated venetian blind systems. For the purpose, a mock-up model was constructed as a prototype of Korean office building with $12.0m{\times}7.3m{\times}3.7m$ ($w{\times}d{\times}h$) and south facing side-window mounted between the clerestory window($2.0m^2$) and the view window($5.6m^2$). The light guide of 1.28m deepth and $29^{\circ}$ tilted angle, is covered with 0.6mm galvanized steel sheet and 97% reflective film. To protect the room from low solar angle, a blind systems, 0.15m deepth and $30^{\circ}$ automated slat angle was installed. To assess illuminance performance, the totally 37 measuring points for illuminance were monitored. For the detailed analysis, photometric sensors were installed at work-plane (8 points), wall (7 points), ceiling (3points), and exterior horizontal illuminance (1 point) respectively. The performance was measured under clear sky and is monitored by Agilent data logger, photometric sensor Li-cor and the Radiant Imaging ProMetric 1400. Comparisons of light factor and uniformity are discussed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.6
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• pp.515-520
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• 2012

A daylighting system includes three parts; light collector, light transformer and light distributor. A DBLP(Double blind light pipe) daylighting system consists of a double blind light collector, a mirror duct type light transformer and a prism film light pipe distributor. The double blinds for a light collection are used to track the sun's altitude and azimuth movements throughout the day. Behind both sets of blinds is the light transformer, which is based on a rectangular cone shaped light duct. The light transformer was designed to efficiently deliver the light into the light pipe within a 30 degree radial spread for the efficient light into the distributor. In this study, DBLP system efficiency was simulated, evaluated and optimized by Tracepro as a popular ray trace light design simulation program. The results indicated that DBLP system efficiency evaluated a maximum 22.4% in case of Spring/Fall season solar noon time. While the overall average system efficiency in the morning and afternoon is evaluated about 10%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.12
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• pp.565-571
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• 2014

Nowadays, to make buildings light weight and aesthetically pleasing, curtain wall structure are commonly used. Therefore, window to wall ratio is increasing, which has caused cooling and heating load in crease in buildings as well. This phenomenon has negative impact from energy point of view. This paper analyzes window and wall convective heat gain when the slat reflectance of external and internal blinds are changed for the better understanding of the fundamentals behind the phenomena. It was observed that, if slat reflectance is increased, window transmitted solar increases and convection heat rate is clearly affected. Among six surfaces including four walls, ceiling and floor, maximum convection heat rate occurs on the south wall in summer. On the other hand, ceiling and floor showed the lowest convection heat gain, since they are shared by adjacent floors.

• KIEAE Journal
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• v.17 no.4
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• pp.75-81
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• 2017

Purpose: Most contemporary office buildings supply external views, a sense of openness and a sense of time to their occupants by adopting the curtain walls, which are equipped with an outer cover having large window area. As a result, the amount of radiation increases, adversely affecting cooling load during the summer in office buildings. Although solar radiation decreases heating load and reduces energy costs during the winter period, due to the characteristics of offices where occupants work largely during daytime, the cooling load is important compared to the heating. Therefore, diverse measures to resolve those trade-offs and annual energy cost have been investigated. Method: In this study, the annual thermal load was comparatively analyzed according to the slat angle of the venetian blind along with lighting control technique. Result: After selecting effective conditions, in order to resolve such issues, this study established automated control strategies of slat angle depending on the window-to-wall ratio and zone orientation, so that the findings of this study can be effectively generalized to other circumstances.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.7
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• pp.429-435
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• 2010

Although recently revised building code requires 15~20% increased thermal insulation performance for window systems, since the code is focusing on winter heat loss, it is not satisfactory to contribute on reducing rapidly rising cooling load in summer. Window systems have great impact on building heat gain and loss. Therefore technological development for window system specialized in shading solar gain in summer is an urgent matter. This study evaluates the performance of sun shading and thermal insulation for blind integrated window system. Also, computer simulation evaluates the effect of heating and cooling energy consumption reduction for an individual unit(floor area of $85m^2$) of a multi-family housing. Physibel Voltra, a heat transfer analysis software, was used to analyse the effect of energy consumption reduction, and the energy load was converted to the cost to compare the actual effect of economical benefit.

• KIEAE Journal
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• v.3 no.1
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• pp.31-36
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• 2003

Recently, buildings with transparent glazing on exterior walls have increased. The transparent glazing on exterior walls gives an impression of opening through introducing external environment's elements to inside of the building, and has various merits and so on, but has defects in controling indoor environments. Especially, the excess of solar radiation in summer increases cooling load causing discomforts to occupants providing radiant environment with high temperature. Cooling load mainly depends on electricity comparing to heating load and intents to centralize specific time. So it is necessary to work out a countermeasure. In this study, showed P building with transparent glazing on exterior walls as a case, investigated indoor thermal performance, numerical analysis of P building in summer through comparing dry-sauna which is represented as radiant environment with high temperature. In the results of this study, transparent glazing space has radiant environment with high temperature such as dry-sauna because of the excess of solar radiation. Accordingly countermeasures are considered in building planning. As concrete methods, there are adiabatic effects using double glazing, use of sunscreen, blind, ventilation facilitation using natural draft, decrease of surface temperature through evaporation cooling and cooling coils.