• Journal of Welding and Joining
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• 제14권2호
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• pp.65-70
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• 1996

Detonation velocity of domestic expolsives was measured using the Dautriche method. The variables employed in this study were the thickness of explosive and the amount of salt added in the ammonium nitrate(AN) explosive. As the results of this study, it was shown that the detonation velocity increases with an increase of explosive thickness but decreases with an increase of salt content. It was further demonstrated that the detonation velocity decreases rather rapidly when the salt content increases over 20 percent. In addition, the accuracy of Dautriche method was evaluated as a preliminary study and its result showed that this method is quite reliable with an experimental error of less than 10 pct.

• 한국수산과학회지
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• 제15권2호
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• pp.147-153
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• 1982

우리나라에서 시판되고 있는 젓갈류 및 채소류의 질산염 및 아질산염함량을 조사한 결과는 다음과 같다. 젓갈류에 있어서 절신염의 함량은 $0.74\sim13.81\;ppm$으로서 종류에 따라 차이가 많았다. 아질산염 함량은 자리돔젓, 새우젓, 꼴뚜기젓, 멸치젓 및 명란젓에서는 소량 검출되었고 갈치젓과 창란젓에서는 검출되지 않았다. 한편, 채소류에 있어서 엽채류의 질신염 함량은 근채류, 과채류에 비해 그 함량이 많았고 특히 상치는$1,320\sim1,412\;ppm$, 배추는 1,572.5 ppm으로서 가장 높았고 부추, 파 및 들깨잎등은 $5\sim219\;ppm$으로서 함량이 낮았다. 과채류의 질산염함량은 가지가 $109.1\sim373.1\;ppm$으로서 다소 높았으나 마늘, 고추 및 토마토에서는 각각 35.1 ppm, 4.09 ppm 및 $4.2\sim7.1\;ppm$으로서 채소류중 그 함량이 낮았다. 아질산염함량은 양배추3.8ppm, 상치 $2.5\sim2.9\;ppm$으로서 비교적 높았으나 배추, 고추, 들깨잎, 마늘 및 우엉에서는 검출되지 않았다. 채소류의 부위별 질산염함량은 배추가 속부분이 210ppm, 겉부분이 682ppm으로서 녹색이 진한 겉부분에 그 함량이 많았으며 미나리는 줄기부분이, 파는 잎부분이 질산염함량이 많았는데 채소류의 증류에 따라 다소 차이가 있었다. 질산염함량은 4일간 저장중 큰 변화는 없었으며, 저온저장과 정온저장한 것을 비교해 보면 상치, 호박 및 시금치등은 저온에서 저장한 것이 높았으며가지, 파등은 상온저장한 것이 함량이 높았다. 본 연구는 부산수산대학 부설 수산식품연구소 1981등도 사업의 일부임.

• 한국대기환경학회지
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• 제33권1호
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• pp.64-74
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• 2017

In this study, we have analyzed relationship between the measured Water Soluble Organic Carbon (WSOC) concentrations and the estimated aerosol water content of $PM_{10}$ (particulate matter with an aerodynamic diameter of less than or equal to $10{\mu}m$) for the period between September 2006 and August 2007 at Seoul, Korea. Water content of $PM_{10}$ was estimated by using a gas/particle equilibrium model, Simulating composition of Atmospheric Particles at Equilibrium 2 (SCAPE2). The WSOC concentrations showed low correlation with Elemental Carbon (EC), but Water Insoluble Organic Carbon (WISOC) were highly correlated with EC. It seemed that hydrophilic groups were produced by secondary formation rather than primary formation. As with the previous studies, WSOC showed good correlation with secondary ions ($NO_3{^-}$, $SO_4{^{2-}}$, $NH_4{^+}$), especially WSOC was highly correlated with $NO_3{^-}$ that is a secondary ion formed by photochemical oxidation from more local sources than $SO_4{^{2-}}$. No apparent correlation between the measured WSOC and estimated water content was observed. However, WSOC showed good correlation with estimated water content when it was assumed that relative humidity was higher than the deliquescence relative humidity of the system. In conclusion, WSOC is correlated with water content by hygroscopic ions and it is expected that nitrate play an important role among the water content and WSOC.

• E2M - 전기 전자와 첨단 소재
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• 제10권2호
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• pp.141-149
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• 1997

L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ powders were prepared by both GNP(Glycine-Nitrate Process) and solid state reaction method in various of calcination temperature(800-1000.deg. C) and time in air. Also, L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ cathode contacts on YSZ(Yttria-Stabilized Zirconia) substrate were prepared by screen printing and sintering method as a function of sintering temperature(1100-1450.deg. C) in air. Sintering behaviors have been investigated by SEM(Scanning Electron Microscope) and porosity measurement. Compositional and structural characterization were carried out by X-ray diffractometer and ICP AES(Inductively Coupled Plasma-Atomic Emission Spectrometry) analysis. Electrical characterization was carried out by the electrical conductivity with linear 4 point probe method. As the calcination period increased in solid state reaction method, L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ phase increased. Although L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ single phase was obtained only for 48hrs at 1000.deg. C, in GNP method it was easy to get single and ultra-fine L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ powders with submicron particle size at 650.deg. C for 30min. The particle size and thickness of L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ cathode contact by solid state reaction method did not change during the heat treatment, while those by GNP method showed good sintering characteristics because initial powder size fabricated from GNP method is smaller than that fabricated from solid state reaction method. Based on enthalpy change from thermodynamic data and ICP-AES analysis, it was suggested to make cathode contact in composition of (L $a_{0.7}$S $r_{0.3}$)$_{0.91}$ Mn $O_{3}$ which have little second phase (L $a_{2}$Z $r_{2}$ $O_{7}$) for high efficient solid oxide fuel cells applications. As (L $a_{0.7}$S $r_{0.3}$)$_{0.91}$Mn $O_{3}$ cathode contact on YSZ substrate was sintering at 1250.deg. C the temperature that liquid phase sintering did not occur. It was possible to obtain proper cathode contacts with electrical conductivity of 150(S/cm) and porosity content of 30-40%.m) and porosity content of 30-40%.

• 생물환경조절학회지
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• 제4권2호
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• pp.144-151
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• 1995

본 실험은 겨울철 파의 양액재배시 배양액 온도를 13, 18, 23$^{\circ}C$로 처리하여 잎파의 생육 및 품질에 미치는 영향을 살펴보고자 수행하였다. 13-23$^{\circ}C$ 범위 내에서 배양액 온도가 증가할수록 생체중도 증가하였다. 초장도 13$^{\circ}C$보다 18, 23$^{\circ}C$ 처리구에서 더 길었으며, 지상부, 지하부 건물율은 18$^{\circ}C$ 처리구에서 가장 무거웠다. 식물체내 K의 함량은 18$^{\circ}C$ 처리구에서 가장 높았으며, Ca, Mg의 함량은 23$^{\circ}C$보다 13, 18$^{\circ}C$ 처리구에서 더 높았다. 비타민 C의 함량은 배양액 온도가 증가할수록 감소하였으나, 유의성은 인정되지 않았다. Pyruvic acid 함량은 13, 18$^{\circ}C$ 처리구에서 높았으며, nitrate의 함량은 반대로 23$^{\circ}C$ 처리구보다 13, 18$^{\circ}C$ 처리구에서 낮았다. 따라서 파의 생육과 품질을 고려한다면, 겨울철 파의 양액 재배시 적절한 배양액 온도는 18$^{\circ}C$ 내외로 생각된다.

• 한국축산시설환경학회지
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• 제3권1호
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• pp.13-18
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• 1997

This study was conducted to investigate the physicochemical changes during the aerobic composting of swine manure mixed with bulking agent, sawdust(v/v, 1:1), in a full-scale composting plant using rectangular escalator-aginated bed composting system. Physical and chemical properties were analyzed on the samples which were collected at 5, 15, and 25 day of composting, curing and final step. The results of this study were summarized as follows; 1. Moisture and K2O content, and pH of final step were higher than those of 5th day of composting (p＜0.05). 2. Ammonium nitrogen, total organic corbon and organic matter content, and electrical conductivity(EC) were significantly decreased (p＜0.05) but nitrate nitrogen, ash and P2O5 content increased(p＜0.05) throughout the aerobic composting process. 3. Total organic carbon per total nitrogen(C/N) and total organic matter per total nitrogen(OM/N) ratio were significantly decreased throughout the aerobic composting process(p＜0.05). 4. Physical and chemical properties of swine manure were varied by aerobic fermentation using rectangular escalor-aginated bed composting system.

• Journal of Ecology and Environment
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• 제33권2호
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• pp.133-139
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• 2010

Atmospheric $CO_2$ concentrations have increased exponentially over the last century and, if continued, are expected to have significant effects on plants and soil. In this study, we investigated the effects of elevated $CO_2$ on the growth of Pinus densiflora seedling and microbial activity in soil. Three-year-old pine seedlings were exposed to ambient as well as elevated levels of $CO_2$ (380 and 760 ppmv, respectively). Growth rates and C:N ratios of the pine seedlings were also determined. Dissolved organic carbon content, phenolic compound content, and microbial activity were measured in bulk soil and rhizosphere soil. The results show that elevated $CO_2$ significantly increased the root dry weight of pine seedling. In addition, overall N content decreased, which increased the C:N ratio in pine needles. Elevated $CO_2$ decreased soil moisture, nitrate concentration, and the concentration of soil phenolic compounds. In contrast, soil enzymatic activities were increased in rhizosphere soil, including ${\beta}$-glucosidase, N-acetylglucosaminidase and phosphatase enzyme activities. In conclusion, elevated $CO_2$ concentrations caused distinct changes in soil chemistry and microbiology.

• 한국초지조사료학회지
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• 제8권3호
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• pp.152-157
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• 1988

The effect of gypsum application was tested on dry matter yield, sulfur uptaken, composition of Ritrogen compound and sulhr compound and sulfur balance in mixed pasture. Total dry matter yields and sulfur uptake by grasses increased with the increasing of gypsum application rates. The ratios between total nitrogen and total sulfur in masses decreased with the increase of sulfur uptake at 2nd and 3rd cutting times. Cysteine content was little affected by gypsum while methionine content slightly increased an 4.0, 6.0 kg3 per 10a levels at 2nd and 3rd cutting times. The uptake of nitrate nitrogen decreased with gypsum application and dry matter digestibility increased about 1.1 to 3.3%. The soil pHs after experiment become high in surface and subsoil till 6.0 kg.S per 10a, but low at 10.0 kg.S per 10a. The content of sulfur in surface soil was 19.9 ppm after experiment, but very high in subsoi1,ranging from 94 to 143 ppm.S. Sulfur leached from the surface soil by 0.69, 2.39, and 6.24 kg.S per 10a in the plots of 4.0, 6.0, and 10.0 kg.S per 10a, respectively.

• Ecology and Resilient Infrastructure
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• 제2권3호
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• pp.247-254
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• 2015

Changes in land-use type can affect soil and water properties in stream ecosystems. This study examined the effects of different land-use types on biogeochemical properties and microbial activities of a stream. We collected water and sediment samples in a stream at three different sites surrounded by varying land-use types; a forest, a radish field and a rice paddy. Nitrogen contents, such as nitrate, nitrite and total nitrogen in the stream water body, showed significant differences among the sampling sites. The highest nitrogen values were recorded at the site surrounded by cropland, as fertilizer runoff impacted the stream. Soil organic matter content in the sediment showed significant differences among sites, with the highest content exhibited at the forest mouth site. These differences might be due to the organic matter in surrounding terrestrial ecosystems. Microbial activities determined by extracellular enzyme activities showed similar values throughout all sites in the water body; however, the activities in the sediments exhibited the highest values near the forest site and mirrored the soil organic matter content values. From these results, we conclude that different land-use types are important factors affecting water and sediment properties in stream ecosystems.

• 한국연초학회지
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• 제16권1호
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• pp.43-52
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• 1994

To investigate the factors of the improvement of cultivation methods according to the plant type, three Burley tobacco cultivars were done. Experiments on the variability of plant type and factors representing the productivity and quality of the cultivar were subsequently carried out in relation to different fertilizer levels. Results are summarized as below. Use of more fertilizer resulted in higher plant height and longer leaf length but smaller mean leaf inclination(MLI). The horizontal leaf area distribution became greater in parts distal to the stem and the vertical leaf area distribution became greater in lower half than in upper half as the amount of fertilizer applied was increased. Br. 49 was the largest but Br. 21 and NTN 77 were similar with respect to both CGR and NAR. The yield was greater in larger MLI cultivars. These three characteristics became greater when the tobacco were heavier in the cultivars of larger MLI and increased with higher amount of fertilizer. Harvest index became greater as the amount of fertilizer decreased but not significantly differ among the cultivars. Total nitrogen content and nitrate - form nitrogen content were greater, more amount of fertilizer, and larger MLI cultivar plots. Total nitrogen content was higher in upper leaves. The filling power of tobacco leaves decreased but combustibility of leaves showed not significant trend as fertilizer application level increased.