• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.1
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• pp.257-264
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• 2019

This paper presents a single image haze removal method via a pixel-based joint BDCP (bright and dark channel prior) and a hierarchical bilateral filter in order to reduce computational complexity and memory requirement while improving the dehazing performance. Pixel-based joint BDCP reduces the computational complexity compared to the patch-based DCP, while making it possible to estimate the atmospheric light in pixel unit and the transmission more accurately. Moreover the bilateral filter, which can smooth an image effectively while preserving edges, refines the transmission to reduce the halo effects, and its hierarchical structure applied to edges only prevents the increase of complexity from the iterative application. Experimental results on various hazy images show that the proposed method exhibits excellent haze removal performance with low computational complexity compared to the conventional methods, and thus it can be applied in various fields.

• Journal of the Korea Computer Graphics Society
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• v.27 no.3
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• pp.1-11
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• 2021

Slow sync is a photography technique where a user takes an image with long exposure and a camera flash to enlighten the foreground and background. Unlike short exposure with flash and long exposure without flash, slow sync guarantees the bright foreground and background in the dim environment. However, taking a slow sync image with a smartphone is difficult because the smartphone camera has continuous and weak flash and can not turn on flash if the exposure time is long. This paper proposes a deep learning method that input is a short exposure flash image and output is a slow sync image. We present a deep learning network with a weight map for spatially varying enlightenment. We also propose a dataset that consists of smartphone short exposure flash images and slow sync images for supervised learning. We utilize the linearity of a RAW image to synthesize a slow sync image from short exposure flash and long exposure no-flash images. Experimental results show that our method trained with our dataset synthesizes slow sync images effectively.

• Journal of Korean Society for Quality Management
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• v.52 no.2
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• pp.185-199
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• 2024

Purpose: The improvement of yield and quality in product manufacturing is crucial from the perspective of process management. Controlling key variables within the process is essential for enhancing the quality of the produced items. In this study, we aim to identify key variables influencing product defects and facilitate quality enhancement in CNC machining process using SHAP(SHapley Additive exPlanations) Methods: Firstly, we conduct model training using boosting algorithm-based models such as AdaBoost, GBM, XGBoost, LightGBM, and CatBoost. The CNC machining process data is divided into training data and test data at a ratio 9:1 for model training and test experiments. Subsequently, we select a model with excellent Accuracy and F1-score performance and apply SHAP to extract variables influencing defects in the CNC machining process. Results: By comparing the performances of different models, the selected CatBoost model demonstrated an Accuracy of 97% and an F1-score of 95%. Using Shapley Value, we extract key variables that positively of negatively impact the dependent variable(good/defective product). We identify variables with relatively low importance, suggesting variables that should be prioritized for management. Conclusion: The extraction of key variables using SHAP provides explanatory power distinct from traditional machine learning techniques. This study holds significance in identifying key variables that should be prioritized for management in CNC machining process. It is expected to contribute to enhancing the production quality of the CNC machining process.

• Korean Journal of Artificial Intelligence
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• v.12 no.4
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• pp.27-33
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• 2024

Various techniques are being researched to effectively detect forest fires. Among them, techniques using object detection models can monitor forest fires over wide areas 24 hours a day. However, detecting forest fires early with traditional object detection models is a very challenging task. While they show decent accuracy for thick smoke and large fires, they show low accuracy for faint smoke and small fires, and frequently generate false positives for lights that are like fires. In this paper, to solve these problems, we focus on leveraging local characteristics such as contours and textures of fire and smoke, which are crucial for accurate detection. Based on this approach, we propose EDAM (Edge driven Attention Module) that performs enhancement by richly utilizing contour and texture information of fire and smoke. EDAM extracts important edge information to generate feature maps with emphasized contour and texture information, and based on this map, performs Attention Mechanism to emphasize key characteristics of smoke and fire. Through this mechanism, the overall model performance was improved, with AP_sincreasing from 0.154 to 0.204 and AP_0.5 from 0.779 to 0.784, resulting in a significant improvement in AP_svalue to 32.47%. In practice, the model applying this technique showed excellent inference speed while greatly improving detection performance for small objects compared to existing models and reduced false positive rates for building and street light illumination in nighttime environments that are easily mistaken for fire.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.275-279
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• 2015

Poly(3,4-ethylenedioxythiophene) : poly(styrenesulfonate) (PEDOT : PSS) has attracted a great deal of attention as a transparent conductive material for organic solar cells or organic light-emitting diodes due to its high electrical conductivity, optical transparency, and excellent mechanical flexibility. It is well known that a solvent doping for PEDOT : PSS thin-films significantly increases the conductivity of films. In this paper, the effect of various kinds of solvent doping and post-treatment on the electrical and structural properties of PEDOT : PSS thin-films is investigated. The solvent doping greatly increases the conductivity of PEDOT : PSS thin-films up to 884 S/cm. A further enhancement of the conductivity of PEDOT : PSS thin-films is achieved by the solvent post-treatment which raises the conductivity up to 1131 S/cm. The enhancement is mainly caused by the depletion of insulating PSS and forming conducting PEDOT-rich granular networks. Strong optical absorption peaks at the wavelength of 225 nm of PEDOT : PSS thin-films indicate the depletion of insulating PSS by post-treatment. We believe that the solvent post-treatment is a promising method to achieve highly conductive transparent PEDOT : PSS thin-films for applications in efficient, low-cost and flexible organic devices.

• 한국해양학회지
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• v.21 no.1
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• pp.13-24
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• 1986

The daily net primary production by phytoplankton in the southeastern sea of Korea in October 1985 ranged from 0.7 to 2.7 gCm$\^$-2/ d$\^$-1/ and averaged to be 1.3 gCm$\^$-2/ d$\^$-1/. Surface total chlorophyll ranged from 0.97 to 3.59mg chlm$\^$-3/. Primary production by nano-phytoplankton(〈20$\mu\textrm{m}$) ranged from 43 to 97% in the surface layer. Optimum light intensity(Iopt)was around 300 to 700${\mu}$Es$\^$-1/m$\^$-1/. Surface primary production from 9:00 to 15:00 h was evidently inhibited by strong light intensity beyond the Iopt. Phytoplankton near the base of euphotic zone(30-40m) showed extremely low Iopt suggesting adaptation to a low light environment. Since Iopt represents the history of light experience of phytoplankton at a given depth, the extent of variation in I of phytoplankton at different depth seems to be related to the in tensity of turbulence mixing in the surface mixed layer. From the present study, ammonium excretion by macrozooplankton (〉350$\mu\textrm{m}$) contributes from 3 to 19% of daily total nitrogen requirement by phytoplandton in this area. Calculation of upward flux of nitrate to the surface mixed layer from the lower layer, based on the simple diffusion model, approximates 3% of nitrogen requirement by phytoplankton. However, large portion of nitrogen requirement by phytoplankton remains unexplained in this area. In upwelling area near the coast, adjective flux might be the major source for the nitrogen requirement by phytoplankton. This study suggests that the major nitrogen source for the phytoplankton growth might come from the pelagic regeneration by nano-and micro-sized heterotrophic plandkon. Enhancement of primary production during the passage of the warm Tsushima Current is discussed in relation with nutrient dynamics and hydrlgraphic processes in this area.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.117-124
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• 2010

The bird strike to small aircraft has not been an issue because of its low speed and usage as a private aircraft. So, the compliance of the bird strike regulation is limited to large fixed-wing aircraft such as the commuter category in FAR Part 23 and the civil aircraft in FAR Part 25, generally. However, the forecast of dramatic increasing of VLJ(Very Light Jet), the usage of a composite material for an aircraft structure and flight time of general aviation due to Air-taxi for the point to point transportation, would rise up the need of bird strike regulations and a safety enhancement in normal and utility categorized aircraft. In this study, the safety of bird strike to small aircraft wing leading edge made of a metal and a composite material were compared using the explicit finite element analysis.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.342-352
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• 2023

Ultra-violet (UV) light is one of abiotic stress factors and causes oxidative stress in plants, but a suitable level of UV radiation can be used to enhance the phytochemical content of plants. The accumulation of antioxidant phenolic compounds in UV-exposed plants may vary depending on the conditions of plant (species, cultivar, age, etc.) and UV (wavelength, energy, irradiation period, etc.). To date, however, little research has been conducted on how leaf thickness affects the pattern of phytochemical accumulation. In this study, we conducted an experiment to find out how the antioxidant phenolic content of kale (Brassica oleracea var. acephala) leaves with different thicknesses react to UV-A light. Kale seedlings were grown in a controlled growth chamber for four weeks under the following conditions: 20℃ temperature, 60% relative humidity, 12-hour photoperiod, light source (fluorescent lamp), and photosynthetic photon flux density of 121±10 µmol m^-2 s^-1. The kale plants were then transferred to two chambers with different CO₂ concentrations (382±3.2 and 1,027±11.7 µmol mol^-1), and grown for 10 days. After then, each group of kale plants were subjected to UV-A LED (275+285 nm at peak wavelength) light of 25.4 W m^-2 for 5 days. As a result, when kale plants with thickened leaves from treatment with high CO₂ were exposed to UV-A, they had lower UV sensitivity than thinner leaves. The Fv/Fm (maximum quantum yield on photosystem II) in the leaves of kale exposed to UV-A in a low-concentration CO₂ environment decreased abruptly and significantly immediately after UV treatment, but not in kale leaves exposed to UV-A in a high-concentration CO₂ environment. The accumulation pattern of total phenolic content, antioxidant capacity and individual phenolic compounds varied according to leaf thickness. In conclusion, this experiment suggests that the UV intensity should vary based on the leaf thickness (age etc.) during UV treatment for phytochemical enhancement.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.95.1-95.1
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• 2010

Transparent conducting ZnO films were deposited to apply DSSC Substrate on glass substrates at $500^{\circ}C$ by ionbeam-assisted deposition. Crystallinity, microstructure, surface roughness, chemical composition, electrical and optical properties of the films were investigated as a function of deposition parameters such as ion energy, and substrate temperature. The microstructure of the polycrystalline ZnO films on the glass substrate were closely related to the oxygen ion energy, arrival ratio of oxygen to Zinc Ion bombarded on the growing surface. The main effect of energetic ion bombardment on the growing surface of the film may be divided into two categories; 1) the enhancement of adatom mobility at low energetic ion bombardment and 2) the surface damage by radiation damage at high energetic ion bombardment. The domain structure was obtained in the films deposited at 300 eV. With increasing the ion energy to 600 eV, the domain structure was changed into the grain structure. In case of the low energy ion bombardment of 300 eV, the microstructure of the film was changed from the grain structure to the domain structure with increasing arrival ratio. At the high energy ion bombardment of 600 eV, however, the only grain structure was observed. The electrical properties of the deposited films were significantly related to the change of microstructure. The films with the domain structure had larger carrier concentration and mobility than those with the grain structure, because the grain boundary scattering was reduced in the large size domains compared with the small size grains. The optical transmittance of ZnO films was dependent on a surface roughness. The ZnO films with small surface roughness, represented high transmittance in the visible range because of a decreased light surface scattering. By varying the ion energy and arrival ratio, the resistivity and optical transmittance of the films were varied from $1.1{\times}10^{-4}$ to $2.3{\times}10^{-2}{\Omega}cm$ and from 80 to 87%, respectively. The ZnO film deposited at 300 eV, and substrate temperature of $500^{\circ}C$ had the resistivity of $1.1{\times}10^{-4}{\Omega}cm$ and optical transmittance of 85% in visible range. As a result of experiments, we provides a suggestition that ZnO thin Films can be effectively used as the DSSC substrate Materials.

• Journal of Plant Biotechnology
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• v.49 no.4
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• pp.307-315
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• 2022

Artemisinin is a secondary metabolite of Artemisia annua that shows potent anti-malarial, anti-bacterial, antiviral, and anti-tumor effects. The supply of artemisinin depends on its content in Artemisia annua, in which various environmental factors can affect the plant's biosynthetic yield. In this study, the effects of different light-emitting diode (LED)-irradiation conditions were tested to optimize the germination and growth of Artemisia annua for the enhanced production of artemisinin. Specifically, the ratio between the red and blue lights in the irradiating LED was varied for investigation as follows: [Red : Blue] = [6 : 4], [7 : 3], and [8 : 2]. Furthermore, additional stress factors like UV-B-irradiation (1,395 ㎼/cm²), low temperature (4℃), and dehydration were also explored to induce hormetic expressions of ADS, CYP, and ALDH1, which are essential genes for the biosynthesis of artemisinin. Quantitative polymerase chain reaction (qPCR) was used to analyze the expression levels of the respective genes and their correlation with the specified conditions. [8 : 2] LED-irradiation was the most optimal among the tested conditions for the cultivation of Artemisia annua in terms of both fresh and dry weights post-harvest. For the production of artemisinin, however, [7 : 3] LED-irradiation with dehydration for six hours pre-harvest was the most optimal condition by inducing around twofold enhancement in the biosynthetic yield of artemisinin. As expected, a correlation was observed between the expression levels of the genes and the contents of artemisinin accumulated.