• Title/Summary/Keyword: Use of sunlight

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Synthesis and Evaluation of Superhydrophobic ODA/PDMS Dip Coating on PET for Liquid-Solid Contact Electrification (액체-고체 접촉대전을 위한 PET 기판 기반 ODA/PDMS 딥 코팅 제조 및 평가)

  • Park, Sunyoung;Kang, Hyungyu;Byun, Doyoung;Cho, Dae-Hyun
    • Tribology and Lubricants
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    • v.37 no.2
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    • pp.71-76
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    • 2021
  • As opposed to using fossil fuels, we need to use eco-friendly resources such as sunlight, raindrops and wind to produce electricity and combat environmental pollution. A triboelectric nanogenerator (TENG) is a device that converts mechanical energy into electricity by inducing repetitive contact and separation of two dissimilar materials. During the contact and separation processes, electron flow occurs owing to a change in electric potential of the contacting surface caused by contact electrification and electrostatic induction mechanisms. A solid-solid contact TENG is widely known, but it is possible to generate electricity via liquid-solid contact. Therefore, by designing a hydrophobic TENG, we can gather electricity from raindrop energy in a feasible manner. To fabricate the superhydrophobic surface of TENGs, we employ a dip coating technique to synthesize an octadecylamine (ODA)- and polydimethylsiloxane (PDMS)-based coating on polyethylene terephthalate (PET). The synthesized coating exhibits superhydrophobicity with a contact angle greater than 150° and generates a current of 2.2 ㎂/L while water droplets fall onto it continuously. Hence, we prepare a box-type TENG, with the ODA/PDMS coating deposited on the inside, and place a 1.5 mL water droplet into it. Resultantly, we confirm that the induced vibration causes continuous impacts between the ODA/PDMS coating and the water, generating approximately 100 pA for each impact.

Three channel Skin-Detection Algorithm for considering all constituent in YCbCr color space (YCbCr 색 좌표계의 모든 요소를 고려한 3-channel 피부 검출 알고리즘)

  • Shin, Sun-Mi;Im, Jeong-Uk;Jang, Won-Woo;Kwak, Boo-Dong;Kang, Bong-Soon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2007.10a
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    • pp.127-130
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    • 2007
  • Skin detection research is important role in the 3G of mobile phone for video telephony and security system by using face recognition. We propose skin detection algorithm as preprocessing to the face recognition, and use YCbCr color space. In existing skin detection algorithm using CbCr, skin colors that is brightened by camera flash or sunlight at outdoor in images doesn't acknowledged the skin region. In order to detect skin region accuracy into any circumstance, this paper proposes 3-channel skin detection algorithm.

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Future water quality analysis of the Anseongcheon River basin, Korea under climate change

  • Kim, Deokwhan;Kim, Jungwook;Joo, Hongjun;Han, Daegun;Kim, Hung Soo
    • Membrane and Water Treatment
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    • v.10 no.1
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    • pp.1-11
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    • 2019
  • The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) predicted that recent extreme hydrological events would affect water quality and aggravate various forms of water pollution. To analyze changes in water quality due to future climate change, input data (precipitation, average temperature, relative humidity, average wind speed and sunlight) were established using the Representative Concentration Pathways (RCP) 8.5 climate change scenario suggested by the AR5 and calculated the future runoff for each target period (Reference:1989-2015; I: 2016-2040; II: 2041-2070; and III: 2071-2099) using the semi-distributed land use-based runoff processes (SLURP) model. Meteorological factors that affect water quality (precipitation, temperature and runoff) were inputted into the multiple linear regression analysis (MLRA) and artificial neural network (ANN) models to analyze water quality data, dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), total nitrogen (T-N) and total phosphorus (T-P). Future water quality prediction of the Anseongcheon River basin shows that DO at Gongdo station in the river will drop by 35% in autumn by the end of the $21^{st}$ century and that BOD, COD and SS will increase by 36%, 20% and 42%, respectively. Analysis revealed that the oxygen demand at Dongyeongyo station will decrease by 17% in summer and BOD, COD and SS will increase by 30%, 12% and 17%, respectively. This study suggests that there is a need to continuously monitor the water quality of the Anseongcheon River basin for long-term management. A more reliable prediction of future water quality will be achieved if various social scenarios and climate data are taken into consideration.

A Study on the Environmental Application of Image Radar for Expanding the Use of Next Generation Medium Satellite 5 (차세대중형위성 5호 활용 확대를 위한 영상레이더의 환경분야 활용 방안 연구)

  • Han, Hyeon-gyeong;Lee, Moungjin
    • Korean Journal of Remote Sensing
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    • v.35 no.6_3
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    • pp.1251-1260
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    • 2019
  • Existing environmental spatial information, which has been concentrated on spatial resolution, has limitations in solving realistic environmental problems that must be accompanied by physical and chemical characterization. Accordingly, there is a need for an image radar capable of identifying physical characteristics of an object regardless of weather conditions, day and night, and sunlight. Image radar is used in various fields in the United States and Europe. The next generation of medium-sized satellite No. 5 in Korea, which is under development with the aim of monitoring water disasters, is also looking for ways to expand the scope to various applications based on the existing application range. To this end, we analyzed domestic and international papers (100 works) using image radar, and reviewed KEI 2016 report, domestic papers, and foreign papers. Based on this, various environmental issues were summarized and the effects of when the image radar was used were analyzed and land cover was selected as an environmental issue. In the future, we will embody the technology to improve the accuracy of the land cover map, which is the environmental issue selected in this study, and build the foundation system for the stable use of the land cover map.

Solar Module with a Glass Surface of AG (Anti-Glare) Structure (연요철(Anti-Glare) 구조의 표면 유리 기판을 가지는 고효율 태양전지 모듈)

  • Kong, Dae-Young;Kim, Dong-Hyun;Yun, Sung-Ho;Bae, Young-Ho;Yu, In-Sik;Cho, Chan-Seob;Lee, Jong-Hyun
    • Journal of the Korean Vacuum Society
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    • v.20 no.3
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    • pp.233-241
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    • 2011
  • Currently, solar module is using the two methods such as a glass-filled method or a super-straight method. The common point of these methods is to use glass structure on the front of solar module. However, the reflectance of the solar module is high depending on the height of the incident sunlight due to the flat surface of the module front glass. Purposed to solve these problems, AG (anti-glare) structures were formed on the glass surface. Next is fabrication methods of AG structure. First, uneven structure made by micro blaster equipment was dipped in Hydro-fluidic acid (HF) acid. HF acid process was carried out to remove particles and to make high transmittance. The reflectance and transmittance of the anti-glare glass was compared to those of the bare glass. The reflectance of anti-glare glass decreased approximately 1% compared with bare glass. The transmittance of anti-glare glass was similar to bare glass. According to the sample angle, the difference of the reflectance between bare glass and the anti-glare glass was about 19%. Isc and efficiency value of anti-glare glass on bare solar cell appeared about 3.01 mA and 0.228% difference compared with bare glass. Anti-glare glass on textured solar cell appeared about 9.46 mA and 0.741% difference compared with bare glass. As a result, the role of anti-glare in the substrate is to reduces the loss of sunlight reflected from the surface. In this study, therefore, AG structure on the solar cell was used to improve the efficiency of solar cell.

VENGEANCE, VIOLENCE, VAMPIRES: Dark Humour in the Films of Park Chan-wook

  • Hughes, Jessica
    • Cross-Cultural Studies
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    • v.28
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    • pp.17-36
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    • 2012
  • This essay places the South Korean film Thirst (2009) within Park Chan-wook's oeuvre as a filmmaker notorious for graphic depictions of violence and revenge. Park's use of dark humour in his films, which is emphasized in Thirst perhaps more than ever, allows for a more self-aware depiction of violence, where both the viewer and the protagonist are awakened to the futility of revenge. This ultimately paints his characters as fascinatingly crazy - simultaneously heroes, villains, and victims. Film theorist Wes D. Gehring's three themes of dark humour ('man as beast,' 'the absurdity of the world,' and 'the omnipresence of death') become most obvious in Park's most recent film, which pays closer attention to character development through narrative detail. Rather than portraying the characters as sentimental, dark humour depicts their misfortunes in an alternative way, allowing for consideration of such taboo subjects as religion, adultery, and death/suicide. These issues are further tackled through Thirst's portrayal of its vampire protagonist, which ultimately de-mystifies the traditional vampire figure. While this character has more often been associated with romance, exoticism and the mystical powers of the supernatural, Thirst takes relatively little from the demons of Nosferatu (Murnau, 1922) and various other Dracula adaptations, nor the romantic figures of Interview with the Vampire (Jordan, 1994), and Twilight (Hardwicke, 2008). Instead, it is part of a much smaller group of contemporary vampire films, which are rather informed by a postmodern reconfiguration of the monster. Thus, this paper examines Thirst as an important contribution to the global and hybrid nature of those films in which postmodern vampires are sympathetic and de-mystified, exhibiting symptoms stemming from a natural illness or misfortune. Park's undertaking of a vampire film allows for a complex balance between narrative and visuals through his focus on the Western implications of this myth within Korean cinema. This combination of international references and traditional Korean culture marks it as highly conscious of New Korean Cinema's focus on globalization. With Thirst, Park successfully unites familiar images of the vampire hunting and feeding, with more stylistically distinct, grotesque images of violence and revenge. In this sense, dark humour highlights the less charming aspects of the vampire struggling to survive, most effective in scenes depicting the protagonist feeding from his friend's IV in the hospital, and sitting in the sunlight, slowly turning to ash, in the final minutes of the film. The international appeal of Park's style, combining conventions of the horror/thriller genre with his own mixture of dark humour and non-linear narrative, is epitomized in Thirst, which underscores South Korea's growing global interest with its overt international framework. Furthermore, he portrayal of the vampire as a sympathetic figure allows for a shift away from the conventional focus on myth and the exotic, toward a renewed construction of the vampire in terms of its contribution to generic hybridization and cultural adaptation.

New Liquid Crystal-Embedded PVdF-co-HFP-Based Polymer Electrolytes for Dye-Sensitized Solar Cell Applications

  • Vijayakumar, G.;Lee, Meyoung-Jin;Song, Myung-Kwan;Jin, Sung-Ho;Lee, Jae-Wook;Lee, Chan-Woo;Gal, Yeong-Soon;Shim, Hyo-Jin;Kang, Yong-Ku;Lee, Gi-Won;Kim, Kyung-Kon;Park, Nam-Gyu;Kim, Suhk-Mann
    • Macromolecular Research
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    • v.17 no.12
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    • pp.963-968
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    • 2009
  • Liquid crystal (LC; E7 and/or ML-0249)-embedded, poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-co-HFP)-based, polymer electrolytes were prepared for use in dye-sensitized solar cells (DSSCs). The electrolytes contained 1-methyl-3-propylimidazolium iodide (PMII), tetrabutylammonium iodide (TBAI), and iodine ($I_2$), which participate in the $I_3^-/I^-$ redox couple. The incorporation of photochemically stable PVdF-co-HFP in the DSSCs created a stable polymer electrolyte that resisted leakage and volatilization. DSSCs, with liquid crystal(LC)-embedded PVdF-co-HFP-based polymer electrolytes between the amphiphilic ruthenium dye N719 absorbed to the nanocrystalline $TiO_2$ photoanode and the Pt counter electrode, were fabricated. These DSSCs displayed enhanced redox couple reduction and reduced charge recombination in comparison to that fabricated from the conventional PVdF-co-HFP-based polymer electrolyte. The behavior of the polymer electrolyte was improved by the addition of optimized amounts of plasticizers, such as ethylene carbonate (EC) and propylene carbonate (PC). The significantly increased short-circuit current density ($J_{sc}$, $14.60\;mA/cm^2$) and open-circuit voltage ($V_{oc}$, 0.68 V) of these DSSCs led to a high power conversion efficiency (PCE) of 6.42% and a fill factor of 0.65 under a standard light intensity of $100\;mW/cm^2$ irradiation of AM 1.5 sunlight. A DSSC fabricated by using E7-embedded PVdF-co-HFP-based polymer electrolyte exhibited a maximum incident photon-to-current conversion efficiency (IPCE) of 50%.

Study on Degradation Characteristic of Plastic Artwork for Conservation (플라스틱 작품 보존을 위한 열화 특성 연구)

  • Yu, Ji A;Cho, Ha Jin;Han, Ye Bin;Lee, Hyun Ju;Lee, Sang Jin;Chung, Yong Jae
    • Journal of Conservation Science
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    • v.31 no.2
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    • pp.87-94
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    • 2015
  • Plastic artwork can be appeared crack, change of color and whitening event by various environment conditions. A large scale plastic artwork often exhibits in outside it will be directly degraded by physical and chemical degradation factor such as strong sunlight, high humidity and rainfall. We should know degradation characteristic of plastics to prevent these damages. In this study, we studied degradation characteristic of plastics (5 types of wide use plastics; polypropylene, polystyrene, polyethylene, polyvinyl chloride, polyurethane) depending on various artificial degradation conditions such as high temperature, ultraviolet and these complex conditions (high temperature and ultraviolet). As a result, polypropylene, polystyrene and polyethylene show the most visible change especially polypropylene, polystyrene. Polypropylene didn't show a great change degree of tensile strength and contact angle, on the other hand polystyrene did. Polypropylene and polystyrene weakened by photo degradation, polyvinyl chloride and polyurethane had relatively good light stability. Also the high temperature and complex conditions were most degradation characteristic. High temperature worked for degradation catalyst because its energy can not enough worked for cut off binding energy of plastics while ultraviolet condition effected as directly degradation condition. Though following results, we expect it can be applied to investigation of degradation factor depending on plastic artwork materials and basic result of plastic artworks conservation.

Analysis of Solar Energy Storage Using Effectiveness on Single Span Plastic Greenhouse with Water Curtain System (수막재배 단동비닐하우스의 태양열 축열이용 효과분석)

  • Lee, S.H.;Ryou, Y.S.;Moon, J.P.;Yun, N.K.;Lee, S.J.;Kim, K.W.
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.200.2-200.2
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    • 2010
  • This study was carried out in order to reduce the amount of underground water which is used in the water curtain system for retaining heat. To proceed to the research, two plastic green houses of water curtain system were installed. One was equipped of internal small tunnel for keeping warm air in the interior of the house. Then the internal small tunnel for keeping warm air was fitted with PVC duct of 50cm in diameter filled with subsurface water. Storing surplus solar energy in the water filled in PVC duct was the method used to this house. Another was installed with FCU in the middle of the house, and was fitted a circulation motor in water tank for heat storage which was operated from 10 a.m. to 4 p.m. in order to interchange heat with FCU. The latter was installed with four FCUs which has a capacity of 8000kcal per hour. Consequently about 5 degrees celsius could be maintained in the interior of the internal small tunnel for keeping warm air with the external temperature of more than minus 5 degrees celsius. It appeared that the alteration of an internal temperature of the house was flexible depending on the sunlight during daytime. It happened that to prevent the water from freezing, mixing antifreezing liquid in the flowing water of FCU or changing the operating method of FCU was a suitable measure. Also, in order to use the surplus solar thermal energy on plastic green house of water curtain system efficiently, storing the surplus heat during daytime simultaneously finding a method of using water curtain systematic underground water happened to be important. As a result of this research, when the house's interior temperature is below zero the operation of FCU appeared to be impossible. Therefore when supposed that the amount of water used in the house is 150~200ton for stable operation of FCU, using the system mentioned in the above research happened to be appropriate of reducing the amount of subsurface water from 80% to 100% when maintaining the interior of internal small tunnel's temperature for keeping warm air of 5 degrees celsius at the extreme temperature of minus 5 degrees celsius.

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Self Care in Depression (우울증의 자기 관리 방법)

  • Lee, Sun-Hea;Park, Yong Chon
    • Korean Journal of Biological Psychiatry
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    • v.14 no.1
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    • pp.5-13
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    • 2007
  • Objectives : Depression disturbs the individual life from the loss of productivity to suicide. Furthermore the whole society is also influenced by depression in social and economic areas. Many scientific treatment methods are known to be effective in depression. But in reality more than half of patients with depression prefer self help treatment rather than medically based treatment. For the patients with mild depression and primary physicians, it is reasonable to provide the evidence based self care including self help or alternative treatment. This study is supported by the Korean Health 21 R&D Project for the Depression Center to establish the Korean treatment guideline for depression. Methods : The members of Depression Center including the authors attended the workshops where the methods of evidence based medicine such as literature search, quality evaluation of the articles, making the level of evidence were educated. The professional librarians helped the authors for get the searched articles. Among the total of 354 abstracts of systemic review and 300 abstracts of random controlled trials, 3 systemic reviews and 2 random controlled trials were the main structure of evaluation. Result : Among the 37 self care methods known to be effective for depression, 11 kinds of methods were worth of evaluation. The first step for the self care of mild depression is to use St. John's wort, exercise, bibliotherapy, and light therapy in depression during winter season. Acupuncture, negative ion therapy, massage, relaxation technique are known to be efective with evidence. Music therapy, hypnotherapy, and aromatherapy are known to be effective but until now the evidences is insufficient and further evaluations are needed. Conclusion : Among 11 listed self-care methods, several methods need more evidence especially in Korean situation. Exercise is the most recommendable evidence based self care method in Korea nowadays. St. John's wort is effective with evidence, but it is not the OTC drug in Korea, so it is not recommendable now. For the bibliotherapy, there is no book such as "Feeling Good" in Korea. Only the introductory book about depression is available. Publishing the self help book based upon cognitive behavioral approach or psychodynamic approach is needed. Light therapy is practiced in a few clinics, but not self-help style. Exposure to the sunlight is recommended in the level of commen sense. These self care methods are for the mild patient. Moderate to severe patients with depression should seek the professional treatment.

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