• Journal of Korean Society for Atmospheric Environment
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• 제22권E2호
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• pp.78-88
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• 2006

In order to study the characteristics of cloud, a real-scale experiment for cloud generation was carried out using an extinct vertical mine (430 m height) located in the northeastern Honshu, Japan. The dry particles generated from the three-step concentrations of NaCl solutions were used for cloud generation. The number size distributions of initial dry particles and cloud droplets were monitored by Scanning Mobility Particle Sizer (SMPS) and Forward Scattering Spectrometer Probe (FSSP) at bottom and upper sites of pit, respectively. The polymeric water absorbent film (PWAF) method was employed to measure liquid water content ($W_L$) as a function of droplet size. Moreover the chemical properties of individual droplet replicas were determined by micro-PIXE. The CCN number concentration shows the lognormal form in dependence of the particle size, while the number size distributions of droplets are bimodal showing the peaks around $9{\mu}m$ and $20{\mu}m$ for every case. In comparison to background mineral particles, right shifting of size distribution line for NaCl particles was occurred. When NaCl solutions with three-step different concentrations were neulized, $W_L$ shows the strong droplet size dependence. It varied from $10.0mg\;m^{-3}$ up to $13.6mg\;m^{-3}$ with average $11.6mg\;m^{-3}$. A good relationship between $W_L$ and cloud droplet number concentration was obtained. Both chemical inhomogeneities (mixed components with mineral and C1) and homogeneities (only mineral components or C1) in individual droplet replicas were obviously observed from micro-PIXE elemental images.

• 한국안전학회지
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• 제16권1호
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• pp.1-8
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• 2001

All objects emit thermal radiation and this radiation is the basis of the techniques used to detect flames. The usual phenomena occurring in the initial stage of the fire are generally invisible products of a combustion and visible smoke. Liquid or gaseous materials do not undergo a smoldering stage so that fires develop very rapidly. Also, the heat generated by the initial flames is usually not sufficient to activate a heat detector. In this case the most effective criterion for automatic fire detection is the flame. According to the fire regulation of korea, the compulsory standard provided that a flame detector shall be installed in a place that the attachment height of detector is higher than 20 m, chemical plants, hangar, refinery, etc.. The results of the research and development are discriminated between a flame and other radiant emitters, developed a UV detector tube contains an inert gas which absorbs UV radiation, developed PZT pyroelectric element is based on the use of photovoltanic cell, developed IR band-pass filter that only allow a 4.3 $\mu\textrm{m}$ radiation wavelength to reach the sensors and developed UV-IR combination flame detector combined into a single detection device.

• Geomechanics and Engineering
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• 제32권1호
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• pp.1-20
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• 2023

To predict the consolidation behavior of dredged and reclaimed marine clays exhibiting consolidation settlement with large strains, the finite strain consolidation theory must be used. However, challenges in appropriately applying the theory and determining input parameters make design and analysis studies difficult. To address these challenges, design charts for predicting the consolidation settlement of reclaimed marine clays are developed by a numerical approach based on the finite strain consolidation theory. To prepare the design charts, a sensitivity analysis of parameters is performed, and influencing parameters, such as initial void ratio and initial height, as well as the non-linear constitutive void ratio-effective stresspermeability relation, are confirmed. Six representative Korean marine clays obtained from different locations with different liquid limits are used. The design charts for estimating the consolidation times corresponding to various degrees of consolidation are proposed for each of the six representative clays. The consolidation settlements predicted from the design charts are compared to those in previous studies and at an actual construction site and are found to agree well with them. The proposed design charts can therefore be used to solve problems related to the consolidation of reclaimed marine clays having large strains.

• 한국안전학회지
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• 제21권1호
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• pp.59-64
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• 2006

In this study, adsorption characteristics of PCBs on granular activated carbon were experimentally investigated in a batch reactor and in a fixed bed reactor. Granular activated carbon removed above 98.4% of initial concentration, 1000mg/L, of PCBs. It was estabilished that the adsorption equilibrium of PCBs on granular activated carbon was more successfully fitted by Freundlich isotherm equation in the concentration range from 1 to 1000mg/L. Because Freundlich parameter, ${\beta}$ is 0.346, removall treatment of PCBs by activated carbon accounts for the fact that toxicity reduction can be achieved through this process. Appearance time of breakthrough curve is faster with the increase flow rate and inflow concentration of liquid. The utility of granular activated carbon is enhanced with the increase of bed height and with the decrease of inflow rate.

• 유기물자원화
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• 제28권1호
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• pp.27-36
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• 2020

본 연구는 친환경 토마토(Lycopersicon esculentum var. cerasiforme) 농가에서 대표적으로 자가 제조되고 있는 액비를 노지에 관주하였을 때 생장과 수량에 어떠한 영향을 미치는지를 구명하기 위하여 수행되었다. 처리는 무처리(물), 유박, 골분+어분, 생선아미노산, 깻묵, 불가사리 액비를 포함하였다. 깻묵과 불가사리 액비의 시기별 pH는 보관 30일 이후에 크게 감소하였고 두 자재의 EC는 0.6~0.8 dS/m으로 가장 높았고 골분+어분액비도 0.4 dS/m 전후로 높은 수준이었다. 액비의 전질소 농도는 불가사리 액비가 0.0062%로 가장 높았고 깻묵(0.0059%) > 골분+어분(0.0030%)순이었고 칼륨도 위의 세 가지 액비에서 가장 높았다. 액비의 인산과 칼슘은 생선아미노산 자재에서 가장 높았고 마그네슘은 식물성인 깻묵 자재에서 유의성 있게 높게 나타났다. 토양 EC는 불가사리 액비 처리구에서 0.74 dS/m로 가장 높았지만 토양과 잎의 대량 무기성분 농도는 처리 간에 차이가 관찰되지 않았다. 잎의 건물중과 엽온 및 줄기의 직경과 초장을 15일에 한 번씩 조사한 결과, 잎 건물중은 시기별로 무처리구에서 대부분 낮았고 초장도 생육 초기에 무처리구에서 가장 작았지만 후기에는 자가제조 액비와 비슷한 수준이었다. 과실수량과 평균과중은 무처리구에서 처리 후 75일 까지 유의성 있게 낮았다. 과실횡경은 골분+어분과 불가사리 액비 처리로 가장 증가하였고 과실 당도와 착색은 생선아미노산 액비구에서 가장 향상되었다. 과실경도는 골분+어분 처리에서 가장 높았다.

• 한국토양비료학회지
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• 제48권3호
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• pp.225-232
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• 2015

We evaluated the effect of mixed liquid fertilizer (MLF) on growth responses of plants and soil chemical properties. A pot experiment with red pepper (Capsicum annuum L.) using loam soil was conducted for 81 days in a temperature-controlled glasshouse, and four N fertilization treatments were laid out in a completely randomized design with three replicates: control (C), chemical fertilizer treatment (CF), and two rates (MLF-0.5 and MLF-1.0) of MLF treatment. Soils were periodically sampled and analyzed for pH, EC(Electrical Conductivity), total N, inorganic N and total C, and some growth characteristics of red peppers were measured. During the experimental periods, the pH of MLF soils was higher than that of CF soils. Soil EC increased right after application of CF or MLF, and the intial increase persisted in CF and MLF soils at the end of experiment. Soil total-N increased right after application of CF or MLF, and this initial increase persisted only in MLF-1.0 soils. Soil inorganic N content initially increased in CF or MLF-1.0 soils, but the initial increase disappeared in 56 days after transplanting. Soil total-C was maintained higher in MLF-1.0 soils and lower in CF soils than in control soils, and the intial increase in MLF-1.0 soils finally disappeared to the level of control soils. Plant height, dry weight of plant organs (shoots, roots and fruit), and the number, diameter and length of red pepper fruits were greatest in CF plants. On the other hand, the effect of MLF-application was different depending on the rate of application. However, no consistent effect of N treatments on some major elements of the organs of red peppers was observed. The amounts of N taken up by plants were 1.3 g for CF, 0.8 g for MLF-1.0, 0.5 g for MLF-0.5 and 0.4 g for control treatments. The results of this study showed that mixed liquid fertilizer (MLF) could appropriately serve as an alternative to chemical N fertilizer in red pepper cultivation.

• 항공우주기술
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• 제4권1호
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• pp.196-202
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• 2005

액체추진기관의 극저온 추진제 공급부에서 추진제의 주입 후 대기시간 동안의 온도상승은 배관내의 geysering 현상 및, 점화시 터보펌프에서의 cavitation을 발생시킬 수 있다. 본 자료에서는 이런 문제를 해결하는 방법 중 하나인 재순환배관 방식에 대하여 KSLV-I 예비안의 산화제부 형상을 바탕으로 LOX를 산화제로 사용한 경우에 있어서 그 성능을 파악하였다. 또한, 다양한 parametric study를 통하여 재순환배관의 설계인자를 찾고자 하였다. 재순환배관의 직경, 초기 LOX 온도, 재순환배관 높이, ullage 압력, 열전달 계수 등의 변화에 의한 영향 및 추가적인 He 분사를 통한 순환 촉진 효과를 살펴보았다. 상용 열유체해석프로그램인 SINDA/FLUINT를 사용하였고 1차원적으로 해석을 수행하였다.

• Plant Biotechnology Reports
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• 제3권3호
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• pp.175-182
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• 2009

Simple, reproducible, high frequency, improved plant regeneration protocol in Eastern Cottonwood (Populus deltoides) clones, WIMCO199 and L34, has been reported. Initially, aseptic cultures established from axillary buds of nodal segments from mature plus trees on MS liquid medium supplemented with $0.25mg\;1^{-1}$ KIN and $0.25mg\;1^{-1}$ IAA. Nodal and internodal segments were found to be extra-prolific over shoot apices during course of aseptic culture establishment, while $0.25mg\;1^{-1}$ KIN concentration played a stimulatory role in high frequency plant regeneration. Diverse explants, such as various leaf segments, internodes, and roots from in vitro raised cultures, were employed. Direct plant regeneration was at high frequency of 92% in internodes, 88% in leaf segments, and 43% in root segments. This led to the formation of multiple shoot clusters on established culture media with rapid proliferation rates. Many-fold enhanced shoot elongation and growth of the clusters could be achieved on liquid MS medium supplemented with borosilicate glass beads, which offer physical support for proliferating shoots leading to faster growth in comparison to semi-solid agar or direct liquid medium. SEM examination of initial cultures confirmed direct plant regeneration events without intervening calli. In vitro regenerated plants induced roots on half-strength MS medium with $0.15mg\;1^{-1}$ IAA. Rooted 5- to 6-week-old in vitro regenerated plants were transferred into a transgenic greenhouse in pots containing 1:1 mixture of vermicompost and soil at $27{\pm}2^{\circ}C$ for hardening and acclimatization. 14- to 15-week-old well-established hardened plants were transplanted to the field and grown to maturity. The mature in vitro raised poplar trees exhibited a high survival rate of 85%; 4-year-old healthy trees attained an average height of 8 m and an average trunk diameter of 25 cm and have performed well under field conditions. The regeneration protocol presented here will be very useful for undertaking genetic manipulation, providing a value addition to Eastern Cottonwood propagation in future.

• 한국지진공학회논문집
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• 제3권4호
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• pp.71-82
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• 1999

자오방향 및 주변방향으로 프리스트레스트 하중이 작용된 축대칭 쉘 구조물을 축대칭요소로 모델화하였다 유체-구조물의 상호관계는 접촉면에서 구조물의 가속도에 비례한 부가질량으로 표현하였으며 부가질량은 유체를 비점성 비압축 및 비회전으로 가정하여 유한요소법에 의해 구하였다. 이에 대한 수치해석을 통하여 고유진동해석 및 지진하중을 주하중으로 한 동적해석을 실시하였다 이때 기하학적으로 축대칭인 구조물의 특성을 최대한으로 이용할 수 있도록 쉘을 링요소로 모델링하였으며 기하학적 비선형관계식에 의하여 동적 모형식을 유도하였다 프로그램을 통하여 해석한 결과를 프리스트레스하중 하에서 고유진동수에 대한 정해와 비교한 결과 20개 이내의 링요소로 모델링한 경우에서도 정해와 근접한 해를 얻을수 있었으며 내부유체가 있는 경우에 대한 고유진동수를 문헌과 비교한 결과 근접한 해를 얻을 수 있었다 내부유체의 높이의 증가에 따라 고유진동수는 현저히 감소하였으며 Wave Number가 적을수록 감소폭이 크게 나타났다. 지진하중에 대한 반경방향의 처짐을 해석한 결과 동일한 크기의 프리스트레스하중이 작용될 때 자오방향의 프리스트레스하중이 작용될 경우가 다소 큰 처짐값을 나타내었다.

• 한국결정성장학회지
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• 제1권2호
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• pp.23-33
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• 1991

Mn-Zn Ferrite는 단결정을 성장하기 위하여 용융하는 동안 불균질 용융과 ZnO휘발의 고유특성을 갖는 재료이다. 그 결과로, 결정성장축을 따라 양이온의 분포가 불균일 하게 된고 또한 기존의 Bridgman법에서는 도가니내에서 용융대가 장시간 유지됨으로써 백금입자가 결정안으로 침입하게된다. 이들은 훼라이트의 자기적 성질을 저하시키는 성질을 갖고 있다. 그러나 새로운 성장법에서는 이러한 단점들을 극복하고 양질의 단결정을 얻기 위하여 결정성장 인자들의 관계를 고찰하였으며 그 인자들은 다음과 같다 : 도가니내의 melt 높이, melt의 표면장력과 밀도, 계면에서의 melt거동, 도가니와 고액계면의 형상, 원료공급속도, 결정성장속도. 아울러, 성장된 결정의 조성을 분석하였을 때 초기조성과 비교하여 $\textrm{Fe}_2\textrm{O}_3$ 1.5 mol%, MnO, Zn 2.0 mol% 이내로 조성 변동은 각각 억제되었고 성장결정면 (110)에서 화확적인 etching 법을 이용하여 광학현미경을 통해 결정내부등을 관찰하였으며, 자기적 특성등을 측정하였다.