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RISS 인기검색어
- 검색키워드
- 저자 : ( Kwanghyun Choi ) (검색결과 63 건)
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KwangHyun Choi,JiYoung Park,SuIn Moon,JinSook Lee 한국색채학회 2017 AIC 2017 Jeju Vol.2017 No.10
The current study took nine teenage youths with lower levels of concentration in order to find which colors and chromas of LED lighting induce emotional stability and concentration. Two experiment spaces were set up, with a size of 1500×1500×2400 mm. The interior was colored with white (S0500-N) paint of N9.5, and in one space, an LED lighting capable of controlling RGB was installed, and in the other space, a D65 standard light source was installed in order to prevent color afterimage and to control the luminous effect of in the eyes. The nine colors used in the experimental space were R, YR, Y, GY, G, BG, B, P, and RP. Each color was made into a high chroma of vivid or strong tones, as well as a middle chroma of soft or light tones, making the total color factors eighteen. For a given color lighting environment, the subjects adopted to the environment for one minute before making an assessment using the SD technique for evaluation items, such as “calming-exciting,” “able to focus well,” and “cannot focus well.” To evaluate concentration, a cube, a pyramid, and a cone with dimensions of 5–7cm in width, depth, and height, and a color of achromatic N5, were provided in the experiment spaces. The subjects’ concentration was evaluated by asking them whether each object could be recognized in a concentrated manner. The following are the results of the experiment For teens with a low level of concentration, yellow colors in middle-level chromas in soft or light tones are the most stable, and blue-green colors were also found to be effective in securing emotional stability. In addition, the color green was found to be more emotionally stable when it was in middle-level chroma than high chroma. In contrast, red, blue, and red-purple in high chroma were found to generate excitement. As for concentration, yellow and blue-green colors in middle-level chromas of soft or light tones generated the most concentration. In contrast, red, blue, purple, and red-purple of high chromas were found to lower concentration and create distractions.
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Quantitative analysis of subjective color appearance based on color and filter transmittance rates
KwangHyun Choi,JiYoung Park,Ho Lee,JinSook Lee 한국색채학회 2017 AIC 2017 Jeju Vol.2017 No.10
Recently, the number of cases in which colored films are put on vehicles or residential windows is increasing to prevent hot summer heat and UV lights inducing skin cancer and aging. However, colored films with a high blocking rate may cause the color constancy, a phenomenon of subjective color appearance. When the film is applied in the wrong way, or part of it is damaged and missing, an optical illusion can occur between the surfaces with and without the film, which leads to confusion and even to an accident. In order to prevent such confusion and potential accidents, we performed color perception experiments according to the color and transmittance, based on which the degree of errors of color perception were derived. Thus, in this study, we identified the tendency of color constancy based on color and filter transmittance rates, and we quantitatively analyzed the degree of errors in color perception by measuring hue, brightness, color purity, and color difference in the Munsell color system. Our experiments were carried out in a space without windows in order to exclude the potential effects of daylight and surrounding artificial light. The inside of the experimental space was finished with N9.5 white (S0500-N) paint. A D65 standard light source was installed on the ceiling. In the experiment, we presented the object in which five different colors such as R, Y, G, B, and P with transmittance rates of 25%, 50%, and 75% were thrown onto the same picture. Subjects were asked to find a color in which a particular shape of N5 was perceived in the Munsell color system and then to write the hue, brightness, and color purity on the evaluation sheet. In addition, we derived a color difference between N5 (original color) and the color that was perceived due to the optical illusion. Thus, we identified the filter color causing the optical illusion the most frequently and the filter transmittance rate.
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Choi, KwangHyun,Sohn, YoungHa,Moon, GeumJu,Kim, YongSang,Jeon, Jae-Hong,Park, KeeChan The Korean Infomation Display Society 2018 Journal of information display Vol.19 No.1
The low-temperature polycrystalline silicon (LTPS) thin-film transistor (TFT) is the optimal device for the backplane of the organic light-emitting diode display. At the end the p-channel LTPS TFT fabrication, a charge-injection stress with a strong negative drain bias and a positive gate bias are applied to reduce the off-current by injecting electrons into the gate insulator near the drain. In this study, the charge density and the length of the charge-injection region in the gate insulator were estimated by comparing the measured TFT characteristics with the simulation models with various charge-injection lengths and charge densities. It was found that the effective length of the charge-injection region was $0.96{\mu}m$ and the charge density was $-3{\times}10^{12}/cm^2$ for the $2-{\mu}m$-channel-length device when $V_{GS}$ was +20 V and $V_{DS}$ was -10 V under the charge-injection stress condition. It was also found, based on the analysis of the electric field distribution under the bias stress condition, that the charge density and the length of the charge-injection region were invariant against the channel length variation. Therefore, the measured TFT characteristics also accorded closely with the simulation models for different channel lengths, such as 4 and $10{\mu}m$, when the same characteristic values of the charge-injection region were employed.
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최광현(Kwanghyun Choi),윤철수(Chulsoo Yoon),오정록(Jeongrok Oh),박지영(Jiyoung Park),이진숙(Jinsook Lee) 한국색채학회 2016 한국색채학회 학술대회 Vol.2016 No.11
식료품의 종류에 따라 광원의 색온도 및 분광 스펙트럼을 달리하여 비춰주면 음식이 더욱 맛있고 신선하게 보인다. 이는 상품의 특정 색을 강조함으로써 소비자들의 시선을 집중시키고 시각적 구매욕을 상승시켜 상품판매를 촉진 시킬 수 있다. 본 연구에서는 다양한 식료품 중 어류를 대상으로 최근 3년 이내에 개장한 백화점과 대형마트의 색온도 적용 현황을 조사하고, 어류가 신선하고 맛있게 보이며 소비자들의 구입 선호도를 높일 수 있는 색온도를 도출하였다. 어류를 비추는 조명의 색온도 적용 현황 조사 결과, 백화점과 대형마트는 약 4,000~4,500 K의 색온도를 사용하는 것으로 나타났다. 또한 실험 결과, 어류에 적합한 색온도는 현재 적용되고 있는 4,000~4,500 K의 색온도인 것으로 도출되었으며, 특히 4,500 K일 때 어류가 가장 신선하고 싱싱하게 보이며, 어류가 가진 표면색이 가장 선명하게 보이는 것으로 도출되었다.
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Na Eun Kim(Na Eun Kim),Sung Sik Kim(Sung Sik Kim),Jihei Sara Lee(Jihei Sara Lee ),Kwanghyun Lee(Kwanghyun Lee),Hyoung Won Bae(Hyoung Won Bae),Sang Yeop Lee(Sang Yeop Lee),Wungrak Choi(Wungrak Choi),Ch 대한안과학회 2023 Korean Journal of Ophthalmology Vol.37 No.3
Purpose: To evaluate the effect of intraoperative mitomycin C (MMC) on the surgical outcomes of ciliary sulcus (CS) Ahmed glaucoma valve (AGV) tube placement. Methods: A retrospective review of medical records of 54 consecutive patients who underwent AGV implantation with tube placed in CS was performed. Consecutive cases operated without the use of intraoperative MMC from 2017 to 2019 were compared with consecutive cases operated with MMC from 2019 to 2021. Surgical failure was defined as intraocular pressure (IOP) exceeding 21 mmHg in two consecutive visits after postoperative 3 months or ≤30% IOP reduction, IOP ≤5 mmHg in two consecutive visits, or loss of light perception. Kaplan-Meier survival analysis and log-rank test were performed to compare the surgical failure rates. Results: A total of 54 eyes of 54 patients were investigated. Mean follow-up period after AGV implantation was 1.4 ± 0.8 years. The MMC group showed significantly lower IOP during the 1st postoperative month (20.5 ± 8.6 mmHg vs. 15.8 ± 6.4 mmHg, p = 0.027), but the difference did not persist 6 months after the surgery (p = 0.805). The mean number of postoperative antiglaucoma medications was significantly lower in the MMC group in the 1st postoperative month (p = 0.047) but no difference was found at 6 months. No statistical difference was noted in the rates of postoperative complications. Kaplan- Meier survival analysis showed comparable survival rates between MMC group and no MMC group (p = 0.356). Conclusions: The intraoperative use of MMC significantly lowered IOP in the 1st postoperative month but did not increase 6 months success rates in patients receiving AGV tube placement in CS.
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A High-Precision Motion Control Based on a Periodic Adaptive Disturbance Observer in a PMLSM
Kwanghyun Cho,Jonghwa Kim,Seibum Ben Choi,Sehoon Oh IEEE 2015 IEEE/ASME Transactions on Mechatronics Vol.20 No.5
<P>This paper presents a novel disturbance compensation scheme to attenuate periodic disturbances on repetitive motion using permanent magnet linear synchronous motors (PMLSMs), and this scheme is called the periodical adaptive disturbance observer. The scheme is based on assumptions that all measured states and disturbances are periodic and repetitive when the tasks executed by PMLSM motion systems have periodic and repetitive characteristics. In the proposed control scheme, a lumped disturbance is estimated by the classical linear disturbance observer (DOB) for the initial time period and stored in memory storages. It consists of parametric errors multiplied by states, friction force, and force ripple, and then, it is updated for each time period by the periodic adaptation law. This scheme requires no mathematical models of disturbances and adaptation laws of model parameters such as the mass of the mover and viscous friction coefficient. Also, it is possible to compensate for disturbances above as well as below the bandwidth of the Q-filter (LPF) of DOB. The effectiveness of the proposed control scheme is verified by various experiments that take into account varying frequency components of disturbances along the operating speed of a mover of PMLSM such as force ripple and friction force.</P>
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Kwanghyun Lee,Heon Yang,Joo Yeon Kim,Wungrak Choi,Gong Je Seong,Chan Yun Kim,Jun Mo Lee,Hyoung Won Bae 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.6
Background: Red ginseng has been found to improve ocular perfusion and dry eye syndrome in glaucomatouseyes; however, its effects on visual function and vision-related quality of life have not beeninvestigated. This study sought to evaluate the effects of red ginseng on visual function and visionrelatedquality of life in glaucoma patients using contrast sensitivity and a questionnaire. Methods: Participants were randomly assigned to two groups in this prospective, randomized, doubleblindstudy: in one group, red ginseng was taken first, followed by a placebo, and in the other, placebowas taken first, followed by red ginseng. We measured and compared changes in contrast sensitivityand vision-related quality of life between the two groups. Contrast sensitivity was measured usingOPTEC® 6500P, and vision-related quality of life was evaluated using the 25-item National Eye InstituteVisual Function Questionnaire. One-way and two-way repeated measure analyses of variance were usedfor the comparison. Relationships between respective changes in dry eye syndrome and contrastsensitivity were also analyzed. Results: Daytime contrast sensitivity and ocular pain improved after the administration of red ginseng. Nighttime contrast sensitivity was improved in early or moderate glaucoma. Improved contrast sensitivitywas not associated with improvement in dry eye syndrome. Conclusion: Red ginseng could improve contrast sensitivity and ocular pain in patients with glaucoma. The mechanism underlying improvement in contrast sensitivity appears to be associated with enhancedretinal perfusion or retinal ganglion cell function, but not dry eye syndrome.
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