• Journal of the Optical Society of Korea
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• 제17권1호
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• pp.22-26
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• 2013

The author analyzes the luminous efficiency of the phosphor-conversion white light-emitting diode (LED) that consists of a blue LED chip and a yellow phosphor. A theoretical model is derived to find the relation between luminous efficiency (LE) of a white LED, wall-plug efficiency (WPE) of a blue LED chip, and the phosphor absorption ratio of blue light. The presented model enables to obtain the theoretical limit of LE and the lower bound of WPE. When the efficiency model is applied to the measured results of a phosphor-conversion white LED, the limit theoretical value of LE is obtained to be 261 lm/W. In addition, for LE of 88 lm/W at 350 mA, the lower bound of WPE in the blue LED chip is found to be ~34%. The phosphor absorption ratio of blue light was found to have an important role in optimizing the luminous efficiency and colorimetric properties of phosphor-conversion white LEDs.

• 한국조명전기설비학회지:조명전기설비
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• 제6권5호
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• pp.19-26
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• 1992

A computer program to calculate the illumination distributions of a room interior was made. The room has a light source with arbitrary intensity distribution. The program follows the paths of the particles from the light sources, and the illumination distribution is calculated by repeating this following to many particles. Monte Carlo method is applied to the decision of the direction of the particle from light source, and the new direction of the reflected particles. Making simulation program on this basis, illumination distributions were measured for various light sources and wall surfaces tocertify the calculated results. As a results, it is known that the calculated distribution would be correct if the size of the light source is sufficiently smaller than the size of the room.

• 한국안광학회지
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• 제15권1호
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• pp.67-71
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• 2010

Purpose: The effect of two different levels of illumination and the effect of three letter chart types on subjective refraction findings were investigated. Methods: This study involved thirty Malay university students aged between 19 to 23 years old (7 males, 23 females), with their spherical refractive error ranged between plano to -7.75D astigmatism ranged from plano to -1.75D, anisometropia less than 1D and with no history of ocular injury and pathology. Monocular subjective refraction was measured under two levels of illumination (with and without room light) and with three different letter charts (Snellen letter chart, wall mounted letter chart and projected letter chart). Subjective refraction finding was calculated in spherical equivalent in unit diopter (D). Results: There was no significant effect in the subjective refraction findings with Snellen letter chart (t-test=0.15, p-value=0.88), projected letter chart (t-test=-0.19, p-value=0.85) as well as wall mounted letter chart (t-test=0.12, p-value=0.94). One Way ANOVA also revealed when the subjective refractive measures were compared under two different level of room illumination (with and without room light), no significant effect of letter chart types on subjective refraction readings with room light ($F_{2.185}$=0.11, p-value=0.89) and without room light ($F_{2.185}$=0.02, p-value=0.98). Conclusions: Subjective refraction findings were not affected whether the room light was on or off. They were also not affected by the types of letter chart used.

• 한국조경학회지
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• 제28권4호
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• pp.21-28
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• 2000

This study is conducted to analyze effects of soil moisture on the growth of maple(Acer palmatum) under indoor low light intensity. Maples grew under three different light intensities such as sunny place(average 353.2W/$m^2$), half shade(average 7.7 W/$m^2$) and shade/(average 1.9W/$m^2$).Under half shady and shady condition, each 24 planters(2 maples planted in each planter) were used and divided into 3 groups treated with different watering points. Three levels of soil water potential were set for watering points, such as -200mbar, -300mbar or -500mbar. Under sunny condition, there were only group of 8 planters, as comparison. Watering was applied when soil water potentials reached -500maber. The results of plant growth experiment are as followed. 1. Under the shady condition, 32 maples died among 48 maples for 7 months. 9 maples survived, watered at soil water potential -200mbar, 5maples at -300mbar and 2maples at -500mbar. 2. Leaf water content ratios were higher under lower light intensity. For the cell wall became thinner under lower light intensity. 3. Maples in shady were easy to die due to having thin cell wall, therefore they were easy to loss the turgor pressure. 4. In case of half shady condition, the group, watered at soil water potential -200mbar, had much smaller amount of rootlet than -300mbar, because there were excessive soil water. The group, watered at soil water potential -500mbar, had smaller amount of rootlet than -300mbar and there was a remarkable difference in leaf water potential in spite of nearly same soil water potential, because leaves received the water stress under lower soil water potential. 5. When maples grew soundly, the leaf water potential was largely influenced by the soil water potential.

• 디자인학연구
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• 제16권1호
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• pp.45-52
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• 2003

현대 교회건축은 그 형태와 공간의 구성 및 디자인방법에서 많은 문제점들을 보여주고 있다. 많은 교회들이 기독교적인 정체성의 표현이 결여된 채 건축되어 지고 있다. 안도 타다오의 교회건축의 특성은 전이공간, 빛과 그림자 그리고 상징의 효과적인 구성으로 나타난다. 전이공간은 한국과 일본 등의 사찰에서의 공간체험의 프로세스를 도입한 것으로 보이며 그것은 예배당을 항해 접근하는 동안 사색의 시간을 제공하며 속의 공간에서 성의 공간으로의 극적인 반전을 가능하게 한다. 안도 타다오는 자립벽을 경계로 성과 속의 공간을 구획하였다. 초기 기독교건축 이래로 빛은 교회건축의 중요한 요소였다. 안도 타다오는 현대교회건축이 잃어버린 빛과 그림자를 효과적으로 도입하여 공간의 깊이와 신성을 표현하였다. 안도 타다오에게서 상징은 모든 것이 절제되어진 그의 건축공간에서 기독교의 정체성을 나타내는 적극적이고 효율적인 표현 방법이다. 그는 상징을 건축이나 공간에 부가적인 요소가 아니라 건축과 일체가 되게 표현함으로서 공간 전체가 하나의 기독교적인 정체성을 나타내는 오브제가 되도록 하였다.

• Restorative Dentistry and Endodontics
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• 제20권2호
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• pp.732-743
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• 1995

The purpose of this study was to evaluate the adaptation of light cured dentin bonding agents to tooth structure by measuring contraction gaps on interfaces between cavity wall and composite resin under SEM study. In this study, class V cavities with cementum margin were prepared on the buccal surfaces of 15 extracted human premolar teeth and teeth were randomly assigned 3 groups of 5 teeth each. The cavities were filled with three dentin bonding agents and two composite resins were investigated for this study: three dentin bonding agents; Scotchbond 2, Scotchbond Multi-Purpose. All-Bond 2, two composite resins; Silux Pius, Z-100. Group 1 : Scotchbond 2 + Silux Plus Group 2 : Scotchbond Multi~Purpose + Z-100 Group 3 : All-Bond 2 + Z-100 The restored teeth were stored in 100% relative humidity at $37^{\circ}C$ for 7 days. And then, the roots of the teeth were removed with the tapered fissure bur and the remaining crowns were sectioned occlusogingivally through the center of restorations. Adaptation at tooth-restoration interface was assesed occlusally, gingivally, and axially by scanning electron microscope. The results were as follows : 1. In Group 1, the adaptation to dentinal wall of Scotchbond 2 was poor, but the adaptation to enamel wall of Scotchbond 2 was excellent. 2. In Group 2, the adaptation to occlusal was axial wall and gingival wall of Scotchbond Multi-Purpose was excellent. Especially in axially wall, the dentin bonding agents infiltrated into dentinal tubules and there was excellent adaptation to dentinal wall. 3. In Group 3, the adaptation to occlusal wall and axial wall of All-Bond 2 was excellent. But in gingival wall, there was gap formation between composite resin and dentin bonding agent.

• 교육시설
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• 제3권1호
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• pp.31-38
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• 1996

In this thesis, we will theoratically and practically study and analyze how the heat flows through an opaque wall, which is by the new material insulated, of a school building in Korea. It will be an important information for the effective using guidelines of the new light throughable insulation materials in Korea.

• Journal of the Korean Wood Science and Technology
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• 제47권5호
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• pp.547-556
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• 2019

Thinned, small larch logs have small diameters and no value-added final use, except as wood chips, pallets, or fuel wood, which are products with very low economic value; however, their mechanical strength is suitable for structural applications. In this study, small larch logs were sawed, dried, and cut into square timbers (with a $90mm{\times}90mm$ cross section) that were laterally glued to form core panels used to manufacture cross-laminated timber (CLT) wall panels. The surface and back of these core panels were covered with 12-mm-thick structural plywood panels, used as cross bands to obtain three-ply CLT wall panels. This attachment procedure was conducted in two different ways: gluing and pressing (CGCLT) or gluing and nailing (NGCLT). The size of the as-manufactured CLT panels was $1,220mm{\times}2,440mm$, the same as that of the plywood panels. The final wall panels were tested under lateral shear force in accordance with KS F 2154. As the lateral load resistance test required $2,440mm{\times}2,440mm$ specimens, two CLT wall panels had to be attached in parallel. In addition, the final CLT panels had tongued and grooved edges to allow parallel joints between adjacent pieces. For comparison, conventional light-frame timber shear walls and midply wall systems were also tested under the same conditions. Shear walls with edge nail spacing of 150 mm and 100 mm, the midply wall system, and the fabricated CGCLT and NGCLT wall panels exhibited maximum lateral resistances of 6.1 kN/m (100%), 9.7 kN/m (158%), 16.9 kN/m (274%), 29.6 kN/m (482%), and 35.8 kN/m (582%), respectively.

• 한국실내디자인학회논문집
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• 제25권6호
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• pp.32-39
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• 2016

The purpose of this study is create a comparative analysis of the characteristics of various materials which were used on the outer wall of F.L.Wright's works. The research results will be summarized as follows: 1) Wright thought that the outer wall was not just a physical object which divides the space of a house but it includes the image of the total exterior form, as well as, the economical factors of the age. 2) He tried to sublimate architectural image of his own style with the change of time because he recognized difficulties and limitations of traditional materials and economic feasibility. 3) He used nature-friendly material like wood and brick which were used in various methods of his natural architectural concept. 4) Some of Wright's early works were acculturated by classical architectural components such as the column to emphasize verticality of architectural form. The columns play a division role in the face of the outer wall creating a dynamic image and this also controls the amount of light that enters inside the house.

• 한국소음진동공학회논문집
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• 제15권4호
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• pp.465-473
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• 2005

The impact sounds, generated by the walking of people, the dropping of an object or the moving of furniture, can be a source of great annoyance in residential buildings. The characteristics and level of this impact noise depends on the object striking the floor, on the basic structure of the floor, and on the finish materials of floor. The focus of this paper is to investigate the amount of improvement impact sound pressure level according to the change of the composition method of ceiling and wall. For this purpose, we tested impact sound pressure level of several cases which is the inserting of mineral wool, the increase of the thickness of air layer, the using of anti-vibration rubber in ceiling and attach the mineral wool on wall in the Floor Impact Sound Test Building of KICT. The results show that the composition method of ceiling and wall is more effective in the reduction of light weight impact sound specially in 125Hz and 250Hz.