• Journal of the Korean Magnetics Society
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• v.18 no.3
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• pp.89-93
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• 2008

Ferrimagnetic Copper-Iron-Chromium Oxide $CuFe_{0.9}Cr_{1.1}O_4$ has been investigated over a temperature range from liquid nitrogen temperature upto $N{\acute{e}}el$ temperature using the Mossbauer technique. Its $N{\acute{e}}el$ temperature is found to be 355 K. Above the $N{\acute{e}}el$ temperature the quadrupole splitting is found to be 0.50 mm/s. On the other hand, all the electric quadrupole shift values are zero below the $N{\acute{e}}el$ temperature within experimental error. These seemingly contradictory phenomena have been explained by the model that the magnetic hyperfine field is randomly oriented with respect to the principal axes of the electric-field-gradient tensor.

• Resources Recycling
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• v.30 no.1
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• pp.53-59
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• 2021

Waste vinyl generated from household waste has been used as a solid refuse fuel (SRF) due to the presence of impurities such as soil, metal, and glass; however, the amount of SRF used has been decreasing owing to recent environmental problems, thereby necessitating the need for recycling. In this study, the mixed recycled raw material produced from household waste vinyl and polyethylene (PE) single recycled raw material produced from agricultural waste vinyl were examined. Raw material analysis revealed that waste vinyl was mainly composed of polyethylene, and approximately 2% of ash remained in the mixed recycled raw material, whereas no ash was found in the PE single recycled raw material. In addition, the analysis of tensile strength according to the mixing ratio of the two recycled raw materials revealed that the highest tensile strength was approximately 16 MPa under the heat treatment temperature of 200 ℃, compression pressure of 30 MPa, and a mixing ratio of 3:7 (mixed:PE single). In addition, the highest bending strength was approximately 39 MPa under the heat treatment temperature of 200 ℃, compression pressure of 30 MPa, and a mixing ratio of 3:7 (mixed:PE single). Therefore, the possibility of recycling waste vinyl was suggested by investigating the change in strength characteristics according to the mixing ratio of the recycled raw materials.

• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.5-16
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• 2003

The aggregate out of waste polyethylene was made in order to recycle waste polyethylene wasted in the country side. Many physical and mechanical experiments which include leaching test, specific gravity test, compaction test, LA abrasion test, large-scaled shear test, and permeability test were performed for the waste polyethylene aggregate. The thermal conductivity test, unfrozen water content test and frost heave test were also performed. The temperature distribution for both gravels and waste polyethylene aggregate, which were constructed in the frost heave layer in the field, was measured in winter season of continuous 2 years and compared.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2003.07a
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• pp.187-192
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• 2003

우리나라의 밭작물 재배 시 잡초발생의 억제, 토양온도 및 수분 유지, 수량증수 등의 목적으로 약 274천㏊가 비닐피복재배를 하고 있으나, 한국자원재생공사에 의하면 2000년도 폐비닐 발생량중 약 48%만이 회수되고 있어 폐비닐에 의해 농토와 주변환경의 오염이 심각한 지경에 이르고 있다. 또한 폐비닐의 수거작업은 인력에 의존하고 있어 많은 노력이 들기 때문에 환경오염을 줄이고 수거노력 절감을 위해 기계화가 절실히 요구되고 있다. (중략)

• Journal of the Korean Magnetics Society
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• v.17 no.1
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• pp.30-33
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• 2007

The $FeIn_2S_4$ exhibits an inverse spinel which Fe ions are occupied to the octahedral(B) site, while In ions are occupied to both the tetrahedral(A) and the octahedral(B) site. The $N\'{e}el$ temperature($T_N$) is determined to be 13 K. The effective moment of $FeIn_2S_4$ found to be $5.094{\mu}_B$ from the fit of Curie-Weiss inverse susceptibility for the temperature range over $T_N$, implying angular momentum contribution. The angular momentum contribution is shown in $M\"{o}ssbauer$ spectra for the antiferromagnetic ordering region($T{\leq}\;13K$), too. A weak $Fe^{2+}(B)-S^2-Fe^{2+}(B)$ interaction is responsible for a low $N\'{e}el$ temperature($T_N$) in $FeIn_2S_4$ system. The temperature dependence of electric quadrupole interaction is explained by z-axial crystalline field energy.

• Journal of the Korean Magnetics Society
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• v.22 no.1
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• pp.15-18
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• 2012

The olivine structured $LiFe_{0.9}Mn_{0.1}PO_4$ material was prepared by solid state method, and was analyzed by x-ray diffractometer (XRD), superconducting quantum interference devices (SQUID) and Mossbauer spectroscopy. The crystal structure of $LiFe_{0.9}Mn_{0.1}PO_4$ was determined to be orthorhombic (space group: Pnma) by Rietveld refinement method. The value of N$\acute{e}$el temperature ($T_N$) for $LiFe_{0.9}Mn_{0.1}PO_4$ was determined 50 K. The temperature dependence of the magnetization curves showed magnetic phase transition from paramagnetic to antiferromagnetic at $T_N$ by SQUID measurement. M$\ddot{o}$ssbauer spectra of $LiFe_{0.9}Mn_{0.1}PO_4$ showed 2 absorption lines at temperatures above $T_N$ and showed asymmetric 8 absorption lines at temperatures below $T_N$. These spectra occurred due to the magnetic dipole and electric quardrupole interaction caused by strong crystalline field at asymmetric $FeO_6$ octahedral sites.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.382-384
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• 2002

본 논문에서는 논리학에서 전통적으로 다루어 온 패턴인 삼단논증의 결론을 DNA 컴퓨팅을 이용해 증명해 내는 방법을 제시한다. 연역 장치로 진리나무 방법의 하나(resolution refutation)를 사용하기 위해서, 삼단논증의 전제들과 결론의 부정을 예화시킨 후 CNF 형태로 바꾸어 준다. 그리고 이것을 이중 가닥의 DNA 분자로 디자인한 후, 해소 반응을 통해 모순, 즉 닐(nil)을 발견하게 되면, 증명은 완료된다.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.1
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• pp.76-84
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• 2013

In this study, thermal weight loss, non-isothermally experiment, chemical composition analysis, calorific value, activation energy (E) were investigated to analysis the kinetic study of RDF, wood pellets, waste wood, waste textile and waste vinyl. When the chemical composition of solidification fuel was compared, the moisture content of RDF was less than the wood pellet and when the kinetic study was compared, the combustion reaction rate of the waste vinyl was higher than any other solidification fuels. However when the combustion efficiency was compared by the activation energy, the RDF had the higher efficiency than other wastes. RDF can be found that the reaction takes place between $320{\sim}720^{\circ}C$ depending on the heating rate.

• Resources Recycling
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• v.17 no.3
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• pp.10-20
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• 2008

In order to study the behaviors of inorganic fillers in recycling of the waste agricultural plastic films, the washed PE fluffs from Shihwa and Jungeup Plant belonging to ENVICO were used respectively. First of all, the test pellets were manufactured by adding of inorganic fillers suchlike calcium carbonate and calpet by certain portions to PE fluffs and then the tested sheets were formed. The mechanical and thermal properties of the samples were measured and compared with others. The items measured were tensile, flexural, Izod impact, HDT, MFT, and so on. Morphologies were also investigated for various samples using the SEM. Finally, optimum ratios between recycled PE and inorganic additives were found out for the best products in physical condition as well as in economic point of view.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1459-1460
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• 2011

자성유체에 60Hz의 교류자기장을 인가할 때 발생되는 냉각효과를 해석하기 위해 유한요소법을 결합하였다. 열원으로는 전류가 코일에 흐를 때 생성되는 줄열과 닐운동과 브라운운동으로 야기되는 전력손실에 의한 발열이 있다. 교류자기장은 주파수가 낮기 때문에 줄열이 주요한 열원이 된다. 그러므로 코일에서 자성유체로 일어나는 열전달과 자연대류현상은 코일의 표면에서 일어난다. 자연대류현상을 해석하기 위해서는 자성유체의 부력밀도를 고려해야 한다. 부가적으로 자계의 세기와 온도에 관한 함수인 자화와 자기체적력밀도로 인해 자기대류현상과 같은 강제대류가 일어난다. 이러한 두 가지 대류현상으로 인해 교류자기장을 인가한 자성유체에서 냉각효과가 일어난다. 자기체적력밀도는 유한요소법으로 보간된 가상공극개념을 이용하여 켈빈전자기력밀도를 이끌어 낸 후 이를 수치적으로 이용하여 구하였다. 랑제방함수는 켈빈전자기력밀도와 전력손실을 계산하는데 필요한 비선형 자화율을 고려하기 위해 사용하였다.