Showing papers by "Ji-Hyun Lee published in 2014"

Analysis of Occupants’ Visual Perception to Refine Indoor Lighting Environment for Office Tasks

Abstract: The combined effects of color temperature and illuminance in a small office on visual response and mood under various lighting conditions were examined in this study. Visual annoyance tests were conducted using a sample of 20 subjects in a full-scale mock-up test space. Computer and paper-based reading tasks were conducted for 500 lx and 750 lx illuminance levels under 3,000 K, 4,000 K and 6,500 K conditions. Two hypotheses were considered for the test in this study. The primary hypothesis was that visual perception is affected by the color temperatures of light sources. The secondary hypothesis was that better moods, such as relaxed and cozy feelings, are associated with low color temperatures given equal illuminance levels. The visual environment under the 3,000 K condition was characterized by glare and brightness, resulting in visual discomfort when target illuminance was higher than 500 lx. Occupants preferred 500 lx under the 6,500 K condition, and 500 lx and 750 lx under the 4,000 K condition, reporting better visual satisfaction when performing office tasks. Prediction models for visual comfort suggest that the less that subjects are visually bothered by light during tasks, the more visual comfort they feel. User satisfaction with light source color is critical for the prediction of visual comfort under different lighting conditions. Visual comfort was the most influential factor on mood. Lower color temperature was associated with better mood at lower illuminance levels, while higher color temperature was preferred at higher illuminance levels.

Evaluation of Artificial Neural Network-Based Temperature Control for Optimum Operation of Building Envelopes

Abstract: This study aims at developing an indoor temperature control method that could provide comfortable thermal conditions by integrating heating system control and the opening conditions of building envelopes. Artificial neural network (ANN)-based temperature control logic was developed for the control of heating systems and openings at the building envelopes in a predictive and adaptive manner. Numerical comparative performance tests for the ANN-based temperature control logic and conventional non-ANN-based counterpart were conducted for single skin enveloped and double skin enveloped buildings after the simulation program was validated by comparing the simulation and the field measurement results. Analysis results revealed that the ANN-based control logic improved the indoor temperature environment with an increased comfortable temperature period and decreased overshoot and undershoot of temperatures outside of the operating range. The proposed logic did not show significant superiority in energy efficiency over the conventional logic. The ANN-based temperature control logic was able to maintain the indoor temperature more comfortably and with more stability within the operating range due to the predictive and adaptive features of ANN models.

Style Analysis Methodology: Identifying the Car Brand Design Trends through Hierarchical Clustering

Abstract: This paper aims to identify car design trends within various automobile manufacturers by investigating two objectives: first, finding similarities between car styles among different car brands from various automobile manufacturers to specify unique car designs which lead the trend; second, identifying the consistency of the brand design characteristics through hierarchical clustering. To do that, Fourier decomposition was used to quantify the car design similarities between 120 cars from 23 different brands. The calculated similarity index is then compared with network centrality measures to identify the clustering of the car brands. The quantified style data then can be applied to accurately predict the design trend. Thus this study can contribute to identify car style trends for strategic design decisions.

Principles of Dynamic Display Aiding Presence in Mixed Reality Space Design

Abstract: In this study, presence principles were developed for dynamic display design and evaluation of dynamic display for designing mixed reality space. This is a research to classify the indicators collected through the researches about the existing measurement and evaluation of the existence felling and information suggestion methods in mixed reality as the evaluation principles of the displays and multimodal's interfaces that construct the mixed reality. Additionally, by constructing QFD evaluation frame based on this presence principles and evaluating the interface that composes the mixed reality, research results were tried to be reflected in the future works.

The Variation of Visual Perception according to the Change of Lighting Environments in a Small Office Space

Abstract: This study examines the influence of color temperature and illuminance levels on occupants' visual perception in a small office space. Field measurements and surveys were conducted in a full-scale mock-up space where four lighting conditions were formed by direct/indirect lighting fixtures. Results imply that the perception of glare increased as color temperature of light increased. Under equal color temperature conditions, the increase of illuminance caused more glare. The glare perception for paper tasks was weaker than that of computer tasks. Subjects felt that space became more spacious as color temperature increased under equal illuminance levels. In order to enhance visual comfort under 3500K conditions, the space should be kept bright and lighting environment needs to be maintained in a way that occupants see letters clearly. Under 5000K conditions, the perception of visually warm and brightness is an influential factor on visual comfort.

Perception of Indoor Visual Environment for Lighting System and Color Temperature Conditions in Office

Abstract: The influences of lighting conditions, which is combined by color temperature and lighting types, on visual responses are discussed in this study. Visual annoyance tests were performed in a full-scale mock-up test space, which was prepared for a small private office environment. Lamps with color temperature of 3,500 K and 5,000 K were applied to a direct lighting type and direct/indirect lighting type. Results indicate that overall glare sensation for computer-based task was stronger than that of paper-based task. Color temperature of 3,500 K applied to a direct lighting type caused the worst glare. Overall, visual discomfort were not reported under all lighting conditions. The direct/ indirect lighting type succeeded to ensure better comfort compared to the direct lighting type. The number of letters which were typed in showed no significant difference under all lighting conditions. In order to enhance good quality of lighting condition, the direct lighting type should ensure good color rendering, reduction of glare and prevention of tensed sensation. The direct/indirect lighting type condition should keep the space and desktop surface bright.

Investigating the Effects of User Age on Readability

Abstract: This paper focuses on creating a guideline for style, line spacing, size, text box and age group combinations of Korean fonts for different electronic displays. Reading time and recall time were measured to analyze the readabilities among various typographical layouts. The importance of typographical elements were different among the age group: line height and font sizes are the most important element for 20s to skim through the documents; font style and line height for 30s; line height and font size for 50+. Although, 20s, 30s and 50s had similarities on recalling speed since the font size and the line heights were the two most important readability elements. Thus, it is clear that the typographical layouts need to be designed differently based on the target user of the design. The optimized font combination for readability was also generated.

The Evolutionary Changes of the Streamlined High-speed Locomotives

Abstract: Introduction The bullet motif of steam locomotives opened the new era of streamlined trains (REF). The movement for efficiency in industrial vehicle design had promoted the exterior outcomes that are not only aesthetically futuristic but also functionally superior (REF). The corpus, so called streamlined trains, was formatted by this design trend appeared in the market as a new locomotive design solution (REF). This international movement was an opportunity that made possible to commercially operate streamlined locomotives in many countries of Europe, America, and Asia (REF). In the level of brand, various manufacturers designed streamlined locomotives and they released these into the market. This trend could be a starting point of the long-term evolution of a streamlined nose – the front head of a train – shape because the design concept was a symbolic representation of futuristic modern identity. In addition, it was functionally suitable to deal with exponentially growing demand for long-distance transportation (REF). Fortunately, there were many technical supports; the fluid dynamics contributed outstanding portion at the transition of locomotive nose exterior design (Hucho, 1998). Technical knowledge gained through manufacturing fighters and commercial airplanes had made a foundation to design an exterior shape that would reduce aero resistance (REF). The design method of streamlined nose shape was developed at a time when aerodynamic designers were developing design methods and shape evaluation methods. After a long time, finally, the designers of a commercial locomotive could break the barrier of 200km/h with the new locomotive The Evolutionary Changes of the Streamlined High-speed Locomotives The quantitative analysis to reveal the changes of bullet motif locomotive design criteria