• 자원리싸이클링
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• 제24권5호
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• pp.15-21
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• 2015

폐플라스틱은 조성뿐만 아니라 다양한 플라스틱의 종류로 인하여 열분해 및 연소 속도가 달라진다. 본 연구는 폐플라스틱 고체 연료 (Refused Plastic Fuel)의 열분해 및 연소 시 설계요소 도출을 위한 열중량 분석 및 동역학 특성을 규명하였다. 열중량 분석기 (Thermogravimetric analysis)의 결과을 이용하여 동력학 특성 중 가장 일반적인 방법인 Kissinger 방법을 통하여 활성화 에너지를 구하였다. TGA의 실험 조건은 다음과 같이 설정하였다. 질소 가스유량 20 ml/min, 승온 속도 $5{\sim}50^{\circ}C/min$ 및 최대온도는 $800^{\circ}C$로 하였다. 본 연구의 폐플라스틱 열분해 특성 연구를 위하여 적용된 방법은 실제의 반응기에서 반응기의 성능, 설계 및 최적 운전조건을 결정할 때 기초자료로 사용될 수 있을 것으로 사료된다.

• Current Optics and Photonics
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• 제4권1호
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• pp.69-80
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• 2020

A Rayleigh Lidar used for wind detection works by transmitting laser pulses to the atmosphere and receiving backscattering signals from molecules. Because of the weak backscattering signals, a lidar usually uses a high sensitivity photomultiplier as detector and photon counting technology for signal collection. The capturing of returned extremely weak backscattering signals requires the lidar to work on dark background with a long time accumulation to get high signal-to-noise ratio (SNR). Because of the strong solar background during the day, the SNR of lidar during daytime is much lower than that during nighttime, the altitude and accuracy of detection are also restricted greatly. Therefore this article describes an ultra-narrow bandwidth filter (UNBF) that has been developed on 354.7 nm wavelength of laser. The UNBF is used for suppressing the strong solar background that degrades the performance of Rayleigh wind lidar during daytime. The optical structure of UNBF consists of an interference filter (IF), a low resolution Fabry-Perot interferometer (FPI) and a high resolution FPI. The parameters of each optical component of the UNBF are presented in this article. The transmission curve of the aligned UNBF is measured with a tunable laser. Contrasting the result of with-UNBF and with-IF shows that the solar background received by a Licel transient recorder decreases by 50~100 times and that the SNR with-UNBF was improved by 3 times in the altitude range (35 km to 40 km) compared to with-IF at 10:26 to 10:38 on August 29, 2018. By the SNR comparison at four different times of one day, the ratio-values are larger than 1 over the altitude range (25~50 km) in general, the results illustrate that the SNR with-UNBF is better than that with-IF for Rayleigh Lidar during daytime and they demonstrate the effective improvements of solar background restriction of UNBF.

• 한국응용곤충학회지
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• 제9권2호
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• pp.91-94
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• 1970

1. 담배 야화병은 비교적 기온과 습도가 낮은 $(18-20^{\circ}C,\; 65-75\%)$, 6월 상순부터 중순에 걸쳐 발생하기 시작했으며 기온과 습도가 점차 높아지는 $(22-26^{\circ}C,\;65-68\%)$ 6월 하순에서 7월 상순 사이에 더욱 빠른속도로 발달했고 7월 중순 이후 8월에 걸친 계절적인 폭풍우가 답배의 잎에 기계적 상해를 줌으로써 야화병의 감염을은 최대로 증가됨을 볼 수 있었다. 2. 약제처리로서는 히도마이신 300-350 배액을 발병기에 2-3회 살포한 것이 가장 효과적이어서 결과적으로 감염율을 $28.3\%$까지 감소시켰다. 3. 크로르피크린에 의한 이식전 토양 처리 (10l/10a)는 기타 병해의 방제를 겸해서 본 병의 피해를 월등히 감소시켰으며 본 포에서의 e담배 생육 상태에도 무처리구에 비해 왕성하였다. 4. 이상의 실험예서 담배 야화병의 효과적인 방제는 조기재배에 의한 수확기의 단축과 6월 상순에서 중순까지의 발병기에 적절한 약제의 살포 그리고 이식전의 토양처리 등을 함으로써 이룩될 수 있다고 본다.

• 대기
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• 제24권1호
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• pp.123-130
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• 2014

계절예측시스템의 배경 지식이 부족한 사용자가 시스템을 효율적으로 구동하고 조절할 수 있도록 자동화에 최적화된 시스템을 기상청 국가태풍센터에 구축하였다. 기존 예측시스템에서 사용자의 주관이 포함되어 자동화 구축에 제약을 주는 군집분류와 예측인자 선정 과정은 미리 수행되고, 그 출력자료는 입력자료로서 제공된다. 시스템을 이해하고 운용하는데 도움을 주기 위해 기상청 규격에 따라 디렉토리 구조를 재구성하고, 해당 디렉토리에 포함되어 있는 입력자료와 소스코드를 이용해 산출되는 출력자료를 정리하였다. 또한 기존 예측시스템에서 고정되어 있거나 수동으로 설정해야 하는 구동조건을 효과적으로 조절하기 위해 네임리스트를 이용한 사용자인터페이스를 추가하여 자동화 시스템을 최적화하였다. 이러한 자동화 시스템에 의해 기술적으로 가능해진 조기예측의 성능을 검증한 결과, 예측시점을 5월에서 1월까지 앞당겨도 모든 진로유형에서 높은 예측성능이 유지되었다. 이처럼, 조기예측이 가능해진 태풍진로 계절예측시스템은 국가태풍센터의 현업예보뿐만 아니라 태풍계절예측 분야의 연구자에게도 매우 유익할 것으로 기대되고, 본 기술노트는 효율적인 예측시스템 운영을 위한 기술적 지침서로 활용될 것이다.

• 한국식품과학회지
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• 제28권5호
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• pp.987-993
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• 1996

본 연구에서는 Bifidobacterium을 우유와 두유에 접종하여 $37^{\circ}C$에서 발효 특성, 적정 발효 기간 및 효율적인 증식을 위한 생육 인자를 찾고자 하였다. 이를 위하여 pH, 산도, glucose함량, 생균수, ${\alpha}-galactosidase$활성 그리고 ${\beta}-galactosidase$활성 변화를 조사하였다. $37^{\circ}C$에서 일반 발효 특성을 측정했을 때 48시간동안 우유의 발효는 pH의 감소와 산 생성의 증가는 현저한 반면, 세포 증식을 24시간동안 증가하였으나 남은 24시간동안은 감소를 보였다. 또한 효소 반응은 ${\beta}-galactosidase$ 활성이 높은 반면, ${\alpha}-galactosidase$는 비교적 낮았으며 glucose 함량은 세포 증식기에 높았다. 두유의 경우는 우유에 비해 pH의 감소가 큰 반면 적정산도 증가는 비슷하였다. 세포 증식은 발효 2일동안 이루어졌으며, ${\alpha}-,\;{\beta}-galactosidase$ 모두 활성이 높게 나타났고, glucose 함량도 1일 동안 지속적인 증가를 나타냈다. 또한 적정 발효기간은 발효유는 24-36시간, 발효 두유는 약 24시간이 바람직한 것으로 나타났다. Bifidobacterium의 성장 촉진 인자의 영향을 발효 시간에 따른 pH와 생균수 변화로 조사한 결과, 두유에서는 fucosyllactose, 그리고 우유에서는 발효 초기에 L-cysteine·HCl, 발효 진행중에는 fucosyllactose가 효과적인 생육 인자로 작용하였다.

• 산업경영시스템학회지
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• 제31권1호
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• pp.41-48
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• 2008

Enhanced machine reliability has dramatically reduced the rate and number of railway accidents but for further reduction human error should be considered together that accounts for about 20% of the accidents. Therefore, the objective of this study was to suggest a new taxonomy of performance shaping factors (PSFs) that could be utilized to identify the causes of a human error associated with railway accidents. Four categories of human factor, task factor, environment factor, and organization factor and 14 sub-categories of physical state, psychological state, knowledge/experience/ability, information/communication, regulation/procedure, specific character of task, infrastructure, device/MMI, working environment, external environment, education, direction/management, system/atmosphere, and welfare/opportunity along with 131 specific factors was suggested by carefully reviewing 8 representative published taxonomy of Casualty Analysis Methodology for Maritime Operations (CASMET), Cognitive Reliability and Error Analysis Method (CREAM), Human Factors Analysis and Classification System (HFACS), Integrated Safety Investigation Methodology (ISIM), Korea-Human Performance Enhancement System (K-HPES), Rail safety and Standards Board (RSSB), $TapRoot^{(R)}$, and Technique for Retrospective and Predictive Analysis of Cognitive Errors (TRACEr). Then these were applied to the case of the railway accident occurred between Komo and Kyungsan stations in 2003 for verification. Both cause decision chart and why-because tree were developed and modified to aid the analyst to find causal factors from the suggested taxonomy. The taxonomy was well suited so that eight causes were found to explain the driver's error in the accident. The taxonomy of PSFs suggested in this study could cover from latent factors to direct causes of human errors related with railway accidents with systematic categorization.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.314-314
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• 2017

Anthropogenic activities have increased the concentrations of greenhouse gases, such as $CO_2$, $CH_4$, $N_2O$, HFCs, $SF_6$, and PFCs, in the atmosphere. Among others, $N_2O$ is well known as an important greenhouse gas accounting for 7.9% of the total greenhouse effect and the effect of its emission is 310 times greater than that of $CO_2$. Agricultural $N_2O$ emissions are now thought to contribute to about 60% of the global anthropogenic $N_2O$ emission, which have been increased primarily due to fertilizer N consumption and manure management. Therefore, the reduction of $N_2O$ emissions in agriculture is being required. This study was conducted to determine the variation of $N_2O$ emissions by no-tillage (NT) and conventional tillage (CT) practices in the cultivation of soybean from the sandy loam soils under the different kinds of fertilizer treatments June through September 2016 in Cheong-ju, Republic of Korea. An experimental plot, located in the temperate climate zone, was composed of two main plots that were NT and CT, and were divided into four plots, respectively, in accordance with types of fertilizers (chemical fertilizer, liquid pig manure, hairy vetch and non-fertilizer). Among all the treatments, $N_2O$ emission was the highest in August and the lowest in June. When $N_2O$ emissions were evaluated during the growing season (June to September) in all fertilizer treatments, NT with hairy vetch treatment emitted the highest $N_2O$ emission in August, whereas, $N_2O$ emissions was the lowest in NT with non-fertilizer treatment in June, respectively (p = 0.05). Based on the cumulative amount of $N_2O$ emissions during the growing season of soybean, NT had lower $N_2O$ emission than CT by 0.01 - 0.02 kg $N_2O$, although NT had higher $N_2O$ emission than CT by 0.03 kg $N_2O$ in only the chemical fertilizer treatments. As a result, it seems that the applications of liquid pig manure and hairy vetch rather than chemical fertilizer could decrease the $N_2O$ emission in NT, compared to CT.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.181.2-181.2
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• 2014

A single-layer graphene has been uniformly grown on a Cu surface at elevated temperatures by thermally processing a poly (methyl methacrylate) (PMMA) film in a rapid thermal annealing (RTA) system under vacuum. The detailed chemistry of the transition from solid-state carbon to graphene on the catalytic Cu surface was investigated by performing in-situ residual gas analysis while PMMA/Cu-foil samples being heated, in conjunction with interrupted growth studies to reconstruct ex-situ the heating process. We found that the gas species of mass/charge (m/e) ratio of 15 ($CH_3{^+}$) was mainly originated from the thermal decomposition of PMMA, indicating that the formation of graphene occurs with hydrocarbon molecules vaporized from PMMA, such as methane and/or methyl radicals, as precursors rather than by the direct graphitization of solid-state carbon. We also found that the temperature for dominantly vaporizing hydrocarbon molecules from PMMA and the length of time, the gaseous hydrocarbon atmosphere is maintained, are dependent on both the heating temperature profile and the amount of a solid carbon feedstock. From those results, we strongly suggest that the heating rate and the amount of solid carbon are the dominant factors to determine the crystalline quality of the resulting graphene film. Under optimal growth conditions, the PMMA-derived graphene was found to have a carrier (hole) mobility as high as ${\sim}2,700cm^2V^{-1}s^{-1}$ at room temperature, which is superior to common graphene converted from solid carbon.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.352-356
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• 2003

A stoichiometric mixture of evaporating materials for $CuGaSe_2$ single crystal am films was prepared from horizontal electric furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal $CuGaSe_2$, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.615\;{\AA}\;and\;11.025\;{\AA}$, respectively. To obtain the single crystal thin films, $CuGaSe_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $610^{\circ}C$ and $450^{\circ}C$, respectively, The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CuGaSe_2$ single crystal thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}$ and $295\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;:\;1.7998\;eV\;-\;(8.7489\;{\times}\;10^{-4}\;eV/K)T^2(T\;+\;335\;K)$. After the as-grown $CuGaSe_2$ single crystal thin films was annealed in Cu-, Se-, and Ga-atmospheres, the origin of point defects of $CuGaSe_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{CU}$, $V_{Se}$, $CU_{int}$, and $Se_{int}$, obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Cu-atmosphere converted $CuGaSe_2$ single crystal thin films to an optical n-type. Also, we confirmed that Ga in $CuGaSe_2/GaAs$ did not form the native defects because Ga in $CuGaSe_2$ single crystal thin films existed in the form of stable bonds.

• 한국포장학회지
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• 제15권2호
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• pp.43-47
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• 2009

0, 5, 15, $25^{\circ}C$의 네 온도에서 단감의 경시적 호흡과 품질변화를 측정하고, 호흡률로부터 최적포장 기체조성을 유지할 수 있는 산소 및 이산화탄소 투과도의 범위를 계산하고 이용가능한 플라스틱 필름의 기체투과도 값과 대비하여 다양한 온도조건에서 적응할 수 있는 포장필름의 요건을 검토하였다. $O_2$ 소비와 $CO_2$ 생산은 온도에 따라 크게 증가하였고 서로간에 거의 비슷한 수준을 유지하였고, 초기를 지나면서 일정한 수준을 나타내었다. 저장 중 주요 품질 변화로는 ascorbic acid 함량변화와 경도 감소가 두드러졌으며, $25^{\circ}C$에서가 다른 온도에 비하여 현저하였다. 온도가 높을수록 요구되는 $O_2$ 및 $CO_2$ 투과도는 증가하였고, 보편적인 플라스틱 필름은 요구수준의 기체투과도를 제공하기에 부족하였다. 여러 온도 조건에서 적용될 수 있는 포장조건을 만족시키기 위해서는 silicone rubber나 미세공성 필름과 같은 고투과성 필름이나 도구의 결합적 설계가 필요한 것으로 평가되었다.