• Polymer(Korea)
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• v.36 no.1
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• pp.76-87
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• 2012

Three kinds of hydroxypropyl cellulose (HPC) derivatives, [6-{4-(4-cyanophenylazo)phenoxy}]hexyloxypropyl celluloses (CAHPCs) with degree of etherification (DET) ranging from 0.4 to 3, fully substituted acrylic acid esters of HPC (HPCA) and CAHPCs (CAHPCAs) were synthesized. The crosslinked HPCA (HPCAG) and CAHPCAs (CAHPCAGs) were also prepared by exposing thermotropic mesophases of HPCA and CAHPCAs to UV light. Both CAHPCs and CAHPCAs with DET ${\leq}$ 1.2, as well as HPC and HPCA, formed enantiotropic cholesteric phases whose optical pitches(${\lambda}_m$'s) increase with temperature, wheras both CAHPCs and CAHPCAs with DET ${\geq}$ 1.4 showed monotropic nematic phases. CAHPCAGs with DET ${\leq}$ 1.2, as well as CAHPCAs with DET ${\leq}$ 1.2, exhibited reflection colors in a wide temperature range. On the other hand, CAHPCAGs with DET ${\geq}$ 1.4, as well as CAHPCAs with DET ${\geq}$ 1.4, showed Schileren textures typical of nematic phase, indicating that the liquid crystalline structure is virtually locked upon photocrosslinking. The isotropization temperatures($T_i$'s) of both CAHPCAs and CAHPCAGs decreased with increasing DET. The $T_i$ of CAHPCAG, however, was higher than that of CAHPCA at the same DET. Moreover, the temperature dependence of ${\lambda}_m$ of CAHPCAGs was much weaker than that of CAHPCAs.

• Journal of Korean Classical Literature and Education
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• no.33
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• pp.185-210
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• 2016

This thesis explores how JobGeuk ShimChungWangWhoJeon and the Devoted daughter ShimChungJeon scenario have transformed ShimChungJeon, a notable work of Pansori literature, dramatically for modern times. By analyzing the adapter's consciousness and changing direction in these two works, it was found that ShimChungJeon was tailored to audiences in the 1900s. JobGeuk and the scenario are attempts to transform ShimChungJeon to meet cultural needs in the 21st century and to make the works appealing to the public. The aspects of the transformation of JobGeuk ShimChungWangWhoJeon are 1) reinforcement of logical causality, 2) weakening the humor and simultaneously emphasizing the work's surreal nature, and 3) dramatic expression by song. The aspects of the change in direction of the Devoted daughter ShimChungJeon scenario are 1)the insertion of a new narrative, 2)trying to evoke both humor and tragic sadness, 3)seeking newness with the reassignment of time and events. JobGeuk ShimChungWangWhoJeon is the first example of the transformation of ShimChungJeon's dramatic style and Devoted daughter ShimChungJeon is the first transformation of its scenario. These two works show how ShimChungJeon can be adapted to modern times and new cultures, and how ShimChungJeon can be made relevant and be enjoyed by the public regardless of the era.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.469-469
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• 2017

기후 변화 및 환경오염으로 인하여 물부족 국가가 세계적으로 증가하고 있는 추세이며, 특히 집중형 강우의 형태가 많아짐에 따라 홍수피해 및 상수공급의 문제가 사회적으로 큰 이슈가 되고 있다. 최근 20여 년간의 급속한 경제성장과 도시화 과정에서 인도네시아는 인구와 산업의 과도한 도시집중으로 지난 1960-80년대 한국이 산업화 과정에서 겪었던 것보다 훨씬 심각한 환경문제에 직면하고 있으며, 자카르타와 반둥을 포함하는 광역 수도권 지역의 물 부족과 수질 오염, 환경문제가 이미 매우 위험한 수준에 도달하고 있는 실정이다. 특히, 찌따룸강 중상류에 위치한 인도네시아 3대 도시인 반둥시는 고질적인 용수부족 문제를 겪고 있다. 2010년 현재 약 일평균 15 CMS의 용수가 부족한 상황이며, 2030년에는 지속적인 인구증가로 약 23 CMS의 용수가 추가로 더 필요한 것으로 전망된다. 이러한 용수공급 문제 해결을 위해 반둥시 및 찌따룸강 유역관리청은 댐 및 지하수 개발, 유역 간 물이동 등의 구조적인 대책뿐만 아니라 비구조적인 대책으로써 기존 및 신규 저수지 연계운영을 통한 용수이용의 효율성을 높이는 방안을 모색하고 있다. 이에 따라 본 연구에서는 해당유역의 용수공급 부족 문제를 해소할 수 있는 비구조적인 대책의 일환으로써 다양한 댐 및 보, 소수력 발전, 취수장 등 유역 내 수리 시설물의 운영 최적화를 위한 지능형 물관리 시스템 적용 방안을 제시하고자 한다. 본 연구의 지능형 물관리 시스템은 센서 및 사물 인터넷(Internet of Things, IoT), 네트워크 기술을 바탕으로 시설물 및 운영자, 유관기관 간의 양방향 통신을 통해 유기적인 상호연계 체계를 제공 할 수 있다. 또한 유역의 수문상황과 시설물의 운영현황, 용수공급 및 수요 현황을 실시간으로 확인함으로써 수요에 따른 즉각적인 용수공급량의 조절이 가능하다. 또한, 빅데이터 분석 및 기계학습(Machine Learning)을 통해 개별 물관리 시설물에 대한 최적 운영룰을 업데이트할 수 있으며, 유역의 수문상황과 용수 수요 현황을 고려하여 최적의 용수공급 우선순위를 선정할 수 있다. 지능형 물관리 시스템 개발의 목적은 찌상쿠이 유역의 수문현황을 실시간으로 모니터링하고, 하천시설물의 운영을 분석하여 최적의 용수공급 및 배분을 통해 유역의 수자원 활용 효율성을 향상시키는 데 있다. 이를 위해 수문자료의 수집체계를 구축하고 기관간 정보공유체계를 수립함으로써 분석을 위한 기반 인프라를 구성하며, 이를 기반으로 유역 유출을 비롯한 저수지 운영, 물수지 분석을 수행하고, 분석 및 예측결과, 과거 운영 자료를 토대로 새로운 물관리 시설 운영룰 및 시설물 간 연계운영 방안, 용수공급 우선순위 의사결정 등을 지원하고자 한다. 본 연구의 지능형 물관리 시스템은 통합 DB를 기반으로 수리수문 현상의 모의 분석을 통해 하천 시설물 운영의 합리적 기준을 제시함으로써 다양한 관리주체들의 시설물운영에 대한 이견 및 분쟁을 해소하고, 한정된 수자원과 다양한 수요 간의 효율적이고 합리적인 분배 및 시설물 운영문제를 해결하기 위한 의사결정도구로써 활용할 수 있을 것으로 기대된다.

• Journal of the Korean Magnetics Society
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• v.8 no.6
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• pp.350-356
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• 1998

$Y_{3-x}La_xFe_5O_{12}$ (x=0.0, 0.25, 0.5, 0.75, 1.0) powders and thin films were fabricated by a sol-gel method and their magnetic properties and crystal structure were investigated by using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and Mossbauer spectroscopy. XRD and Mossbauer spectroscopy measurements show that garnet powders annealed at 900 $^{\circ}C$ for 8 hours were single-phased and that thin films fired at 800 $^{\circ}C$ for 2 hours were crystallized without any preferred direction. X-ray diffraction patterns of $Y_{3-x}La_xFe_5O_{12}$ powders annealed at 1000 $^{\circ}C$ had only peaks of the garnet structure in case of x$\leq$0.75 but those of $Y_2LaFe_5O_{12}$ powders consisted of peaks from garnets and $LaFeO_3$. Mossbauer sepectra of garnet powders grown by the sol-gel method had a similar shape of those of powders grown by a conventional ceramic method. Grain sizes of garnet powders were 200~300 nm and the averaged surface roughness was 3.17 nm. Results of VSM measurements show the powders and thin films had soft magnetic properties and that the garnet powders had the largest saturation magnetization, 30 emu/g, and the lowest coercivity, 52 Oe.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.25 no.2
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• pp.61-67
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• 2012

Objective : The endpoint of this trial is to verify therapeutical availability of conventional western eyedrops combined with acupuncture treatment by means of BUT(tear film break-up time), Schirmer's test, which have been considered to be typical methods for diagnosing dry eye syndrome. Methods : The subjects of this trial included the outpatients who had been diagnosed with dry eye syndrome in Pusan national university hospital and underwent acupuncture treatment from March 2011 to April 2011. They received acupuncture treatment once a week, three times while constantly using Restasis or artificial tears. We collated and analyzed the outcome data of Schirmer's test and BUT conducted at the beginning of this trial and three times more after each acupuncture treatments. Acupoints, such as, Chanjuk(BL2), Eoryo, Sajukgong(TE23), Taeyang, Sabaek(ST2), limited around both eyes were selected based on their clinical effects referring to medical books. Results : 1. From BUT test results, Restasis and acupuncture combined group showed statistically significant difference, however, artificial tears and acupuncture combined group showed difference only between before and after the treatment, which is not statistically significant. 2. From Schirmer's test results, Restasis and acupuncture combined group showed statistically significant difference, however, artificial tears and acupuncture combined group showed difference only between before and after the treatment, which is not statistically significant. 3. The average duration of treatment was statistically 16.3 days for Restasis and acupuncture combined group. Conclusions : Combination of acupuncture and Restasis for dry eye syndrome can shorten the duration of treatment. Therefore, clinical benefit is expected to be worth.

• Journal of the Korean Institute of Gas
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• v.25 no.4
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• pp.27-35
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• 2021

Recently, as a solution to the sharp drop in "power reserve ratio", it is being converted to a microgrid that enables bi-directional transmission and distribution. A microgrid is composed of a small-scale distributed power supply and a load. As a representative technology of distributed power generation, there is a Micro Combined Heat and Power system applied to homes and buildings. In this study, a safety standard was developed by dividing the power generation system, cooling system, lubrication system, and exhaust system to derive safety standards for a small gas engine power generation system with a gas consumption less than 232.6kW (200,000 kcal/h). In the case of the power generation system, a filter was installed and the system was stopped by detecting gas leakage and abnormalities in engine speed or output and the cooling system is stipulated to stop the system in case of insufficient cooling water or overheating. The lubrication system monitors the pressure and temperature of the lubricating oil and stops the system when an abnormality occurs, and the exhaust gas emission concentration regulation value was specified in accordance with domestic and foreign standards. Through the results of this study, it is judged that the safety of the gas engine power generation system can be improved and it can contribute to the commercialization of products.

• Korean Journal of Optics and Photonics
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• v.32 no.4
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• pp.147-152
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• 2021

We report high-power continuous-wave operation of a Yb-doped fiber laser at 1070 nm, pumped by high-power laser diodes at 976 nm. Based on theoretical calculation of the stimulated Raman scattering and temperature distribution in the fiber, we construct a bidirectionally pumped Yb-fiberlaser system incorporating a pair of fiber Bragg gratings and a cladding light stripper. The fiber laser yields 3.0 kW of continuous-wave output at 1070 nm in a diffraction-limited beam with M² ≈ 1.26 for 4.1 kW of incident pump power, corresponding to a slope efficiency of 81.5%. The prospects for further power scaling are discussed.

• International Area Studies Review
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• v.14 no.1
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• pp.99-119
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• 2010

This study explores the natural gas market and the oil market in the U.S. and the European oil market. It focuses on two kinds of analyses; one is to confirm whether there is the predictive power between spot and futures within homogeneous commodity market(or inter-heterogeneous commodity market) through Granger-causality test in terms of the return rate and the volatility. The other is to examine the spot price stabilizing effect of futures price through regression analysis. When it comes to the predictive power of inter-commodity market, there was a conflicting aspect between the return rate of spot and futures. Overall, however, its statistical significance was low. With respect to the volatility, we found that the natural gas market has little influence on the oil market unlike the predictive power of oil market on natural gas market. Concerning the return rate of the predictive power within homogeneous commodity market, we found that the return rate of spot has the predictive power on futures only in the European market. In addition, we identified that there is feedback between spot and futures in the all commodity markets regarding volatility. As a result of the spot price stabilizing effect analysis of futures price, futures volatility increased the spot volatility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.25-34
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• 2019

Recently, when a fault occurs at a long-distance point in a LVDC (low voltage direct current) distribution feeder in a light rail system, the magnitude of the current can decrease to less than that of the load current of a light rail system. Therefore, proper protection coordination method to distinguish a fault current from a load current is required. To overcome these problems, this paper proposes an optimal algorithm of protection devices for a LVDC distribution feeder in a light rail system. In other words, based on the characteristics of the fault current for ground resistance and fault location, this paper proposes an optimal operation algorithm of a selective relay to properly identify the fault current compared to the load current in a light rail system. In addition, this paper modelled the distribution system including AC/DC converter using a PSCAD/EMTDC S/W and from the simulation results for a real light rail system, the proposed algorithm was found to be a useful and practical tool to correctly identify the fault current and load current.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.1
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• pp.21-28
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• 2019

Reversible solid oxide fuel cell (ReSOC) system was integrated with waste steam for electrical energy storage in distributed energy storage application. Waste steam was utilized as external heat in SOEC mode for higher hydrogen production efficiency. Three system configurations were analyzed to evaluate techno-economic performance. The first system is a simple configuration to minimize the cost of balance of plant. The second system is the more complicated configuration with heat recovery steam generator (HRSG). The third system is featured with HRSG and fuel recirculation by blower. Lumped models were used for system performance analyses. The ReSOC stack was characterized by applying area specific resistance value at fixed operating pressure and temperature. In economical assessment, the levelized costs of energy storage (LCOS) were calculated for three system configurations based on capital investment. The system lifetime was assumed 20 years with ReSOC stack replaced every 5 years, inflation rate of 2%, and capacity factor of 80%. The results showed that the exergy round-trip efficiency of system 1, 2, 3 were 47.9%, 48.8%, and 52.8% respectively. The high round-trip efficiency of third system compared to others is attributed to the remarkable reduction in steam requirement and hydrogen compression power owning to fuel recirculation. The result from economic calculation showed that the LCOS values of system 1, 2, 3 were 3.46 ¢/kWh, 3.43 ¢/kWh, and 3.14 ¢/kWh, respectively. Even though the systems 2 and 3 have expensive HRSG, they showed higher round-trip efficiencies and significant reduction in boiler and hydrogen compressor cost.