• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.225-232
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• 1992

In order to develop an enzyme-linked immunosorbent assay(ELISA) for detecting aflatoxin $B_1(AFB_1)$, we produced and purified antibodies, thereafter established and evaluated methods of direct and indirect competitive ELISA. Anti-AFB, antisera, produced by immunizing rabbits with $AFB_1$-1-(0-carboxymethy1)oxime-bovine serum albumin conjugate ($AFB_1$-BSA), were removed of anti-BSA antibodies by quantitative precipitation reaction and further purified by ammonium sulfate precipitation and DEAE-Sephadex A-50 ion exchange chromatography. Purified IgG fractions were used as anti-$AFB_1$ antibodies. The antibodies, whose titer was deterrnined extremely high above $2 \times 10^6$, showed low cross-reactivity of 3~34% against $AFB_1$ analogues such as G2, B2, and GI. From the standard curves of direct and indirect competitive ELISA for AFBI, the detection ranges were found 0.2~20 and 1~10, 000 ng/ml(ppb) respectively. In their sensitivity, stability, simplicity, and rapidity, the direct method was more suitable than the indirect method for practical use.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.2
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• pp.105-112
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• 2005

The electrolytic reduction of uranium oxide in a LiCl-Li$_{2}$O molten salt system has been studied in a 10 g U$_{3}$O$_{8}$ /batch-scale experimental apparatus with an integrated cathode assembly at 650$^{\circ}C$. The integrated cathode assembly consists of an electric conductor, the uranium oxide to be reduced and the membrane for loading the uranium oxide. From the cyclic voltammograms for the LiCl-3 wt$\%$ Li$_{2}$O system and the U$_{3}$O$_{8}$-LiCl-3 wt$\%$ Li$_{2}$O system according to the materials of the membrane in the cathode assembly, the mechanisms of the predominant reduction reactions in the electrolytic reactor cell were to be understood; direct and indirect electrolytic reduction of uranium oxide. Direct and indirect electrolytic reductions have been performed with the integrated cathode assembly. Using the 325-mesh stainless steel screen the uranium oxide failed to be reduced to uranium metal by a direct and indirect electrolytic reduction because of a low current efficiency and with the porous magnesia membrane the uranium oxide was reduced successfully to uranium metal by an indirect electrolytic reduction because of a high current efficiency.

• Journal of the Korea Society of Computer and Information
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• v.28 no.10
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• pp.197-205
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• 2023

This study is to apply the Havruta teaching-learning method to college students' major classes and analyze the relationship between the effectiveness evaluation of communication skills and sub-factors using a structural equation model. As a result of the study, the communication ability score was different before and after Havruta teaching-learning, and it was found that after Havruta teaching-learning was higher than before Havruta teaching-learning. The path effect was found to be significant in all of the total, direct, and indirect effects among latent variables, except for the relationship between interpretation ability, role-playing ability, and goal-setting ability in the direct effect. In this study, it was found that the Havruta teaching-learning method not only improves creativity and thinking ability, but also improves self-directed learning ability. In addition, it was reconfirmed that it is a teaching-learning method that can develop social skills and communication skills as well as problem-solving skills while experiencing opinions different from one's own. As a result, research on a thorough student-centered teaching-learning method suitable for the Homo Machina era must be continued and its application in the educational field must be implemented.

• Journal of Venture Innovation
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• v.5 no.2
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• pp.85-99
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• 2022

Dryers becoming commercially available for experimental and industrial use are classified to general drying oven, hot-air dryer, vacuum dryer, freezing dryer, etc. and kinds of them are various from the function, size and volume, etc. But the moisture measurement is not applied although it is important factor for the quality control and the performance improvement of products, and then now is very passive because the weight is weighed arbitrarily after dry-end. Generally the method for measuring moisture is divided by a direct measurement method and a indirect measurement method, and the former such as the change of weight or volume on the front and rear of separation of moisture, etc. is mainly used. Relatively a indirect measurement is very limited to apply due to utilize measurement apparatuses using temperature conductivity and micro-wave etc. In this research, we easily designed the moisture measurement system using the open-source based Arduino, and monitored moisture fluctuations and weight profiles in the real-time without the effect of external environment. Concretely the temperature-humidity and load cell sensors were packaged into a drying oven and the various change values were measured, and their sensors capable to operate 60℃ and 80℃ were selected to suitable for the moisture sensitive materials and the food dry. And also the performance safety using the organic samples of banana, pear, sawdust could be secured because the changes of evaporation rate as the dry time and temperature, and the measurement values of load cell appeared stable response characteristics through repeated experiments. Hereafter we judge that the reliability can be improved increasingly through the expansion of temperature-humidity range and the comparative analysis with CFD(Computational Fluid Dynamics) program.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.98-105
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• 2018

Cracks in RC members occurred as a result of material and structural factors. The crack width and a crack location are very difficult to examine. A direct crack control method and indirect crack control method to control a crack are presented in the KHBDC (LSD) and KSCDC (2012). In the KSCDC text, cracks are controlled by steel spacing indirectly under a service load. On the other hand, in the KSCDC appendix, cracks are controlled by a crack width directly under a sustained load. In particular, the loading state considered is different. On the other hand, cracks are controlled under a combination of service load and an effective elastic modulus is used in KHBDC. Therefore, in this study, an effective elastic modulus that can reflect the ratio of the sustained load and live load was applied, and a maximum steel spacing was calculated through a design crack width. A variable interpretation was carried out, and a rational crack control method was assessed. As a result, a steel spacing through the design crack width in the KSCDC was smaller than that from the design crack width in the KHBDC, which leads to a conservative design. In addition, the maximum steel spacing suggested in this study has a consistency eliminating the difference between direct crack control and indirect crack control.

• Journal of Korean Association for Spatial Structures
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• v.10 no.1
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• pp.127-134
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• 2010

The dynamic instability for snapping phenomena has been studied by many researchers. Few paper deal with the dynamic bucking under the load with periodic characteristics, and the behavior under periodic excitation is expected the different behavior against STEP excitation. We investigate the fundamental mechanisms of dynamic instability when shallow EP(Elliptic Paraboliodal) shell of two degree of freedom are subjected to sinusoidal excitation with direct snapping and indirect snapping. By using Newmark-$\beta$ method, we can get the nonlinear response, and characteristics of the dynamic instability through the running response spectrum by FFT(fast Fourier Transform) and attractors are compared in the phase plane. Dynamic buckling loads are strongly influenced by the relationships between the natural frequency of structures and the dominant frequency of incident excitations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.120-129
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• 2023

Hanger cable tension is a major response that can determine the integrity and safety of suspension bridges. In general, the vibration method is used to estimate hanger cable tension on operational suspension bridges. It measures natural frequencies from hanger cables and indirectly estimates tension using the geometry conditions of the hanger cables. This study estimated the hanger cable tension of the Palyeong Bridge using a vision-based system. The vision-based system used digital camcorders and tripods considering the convenience and economic efficiency of measurement. Measuring the natural frequencies for high-order modes required for the vibration method is difficult because the hanger cable response measured using the vision-based system is displacement-based. Therefore, this study proposed a back analysis technique for estimating tension using the natural frequencies of low-order modes. Optimization for the back analysis technique was performed by defining the difference between the natural frequencies of hanger cables measured in the field and those calculated using finite element analysis as the objective function. The direct search method that does not require the partial derivatives of the objective function was applied as the optimization method. The reliability and accuracy of the back analysis technique were verified by comparing the tension calculated using the method with that estimated using the vibration method. Tension was accurately estimated using the natural frequencies of low-order modes by applying the back analysis technique.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.2
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• pp.171-178
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• 2014

After the expiration of operating license of a plant, all infrastructures within the plant must be safely dismantled to the point that it no longer requires measures for radiation protection. Despite the fact that Kori 1 and Wolsong 1 are close to the expiration of their operating license, sufficient technologies for radiological characterization, decontamination and dismantling is still under development. The purpose of this study is to develop one of methods for radiological inventory assessment on measuring object by using direct measure of large component with In-Situ measurement technique. Radiological inventory was assessed by analyzing nuclide using portable gamma spectroscopy without dismantling reactor head, and the result of direct measurement was supplemented by performing indirect measurement. Radiochemical analysis were performed on surface contamination samples as well. During the study, radiological inventory of reactor vessel calculated expanding the result. Based on the result and the radioactivity variation of each radionuclides time frame for decommissioning can be decided. Thus, it is expected that during the decommissioning of plants, the result of this study will contribute to the reduction of radiation exposure to workers.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.159.2-159.2
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• 2014

간접띠간격(indirect bandgap)을 갖는 층상형 반도체 $MoS_2$는 두께가 줄어들어 단일층이 되면 층간 상호작용의 변화로 인해 ~1.8 eV의 직접띠간격(direct bandgap)을 갖게 된다. 이러한 초박형 $MoS_2$의 발광 특성을 활용하기 위해서는 원자 크기 수준에서 두께와 물성을 조절할 수 있는 화학적 표면개질법에 대한 이해가 필요하다. 최근 아르곤(Ar) 플라즈마를 이용한 $MoS_2$의 층상(layer-by-layer) 식각과 표면제어에 관한 연구결과가 보고되었으나 자세한 반응 메커니즘은 알려져 있지 않다. 본 연구에서는 산소 플라즈마에 의한 단일층 및 복층 $MoS_2$의 산화반응을 원자힘 현미경(AFM), 광전자 분광법(XPS), 라만 및 광발광 분광법을 통해 관찰하고 반응 메커니즘을 이해하고자 한다. 플라즈마로 생성된 산소라디칼과의 반응시간이 증가함에 따라 $E{^1}_{2g}$와 $A_{1g}$-진동모드에서 기인하는 라만 신호, 그리고 A와 B-엑시톤에서 유래하는 광발광의 세기가 감소함을 확인하였다. XPS와 AFM을 통해 반응이 진행됨에 따라 $MoS_2$의 상층이 $MoO_3$로 산화되면서 나노입자로 응집되어 표면형태가 변화하는 것을 확인하였다. 이 결과는 플라즈마 산화반응을 이용하여 $MoS_2$ 표면에 구조적 결함(defect)과 층상 식각을 유발하고 광발광 특성 제어를 위해 전자구조를 조절할 수 있다는 가능성을 보여준다.

• 한국벤처창업학회:학술대회논문집
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• 2017.04a
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• pp.62-62
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• 2017

최근 인공지능 시대 및 제 4차 산업 혁명 시대의 도래로 제품 간, 제품과 서비스 간, 서비스 간 산업이 다양한 형태로 진화 중이며, 이종기술 산업 간의 융 복합화로 새로운 제3의 신산업이 등장하고 있다. 또한 소위 말하는 O2O(Online to Offline)는 이미 운송, 금융(핀테크), 자동차(카테크), 숙박, 음식, 의료(헬스케어테크) 등 많은 산업 분야에 진출, 기존 전통 산업과 충돌, 인허가에 어려움을 겪고 있으며 이러한 O2O는 IOT(사물인터넷)로 급속도로 가속화 되고 있다. 이렇듯 4차 산업 혁명에 따른 신산업의 탄생은 산업의 경계를 붕괴하고 있음에도 산업별로 구분된 제도, 규제, 지원정책 등은 여전히 신산업 창업의 장애가 되고 있다. 이에, 본 연구에서는 국내 벤처특별법, 창업지원법, 1인 창조기업법 내 투자 지원 업종과 미국을 비롯한 해외 창업 관련법 내 창업 지원 제한 업종과의 비교 분석, 몇 가지 중요한 시사점을 도출했다. 먼저, 우리나라가 선진국에 비해 지나치게 투자 제한 업종이 많음을 확인했다. 또한 선진국은 미풍양속을 해치는 업종, 투기적 사업 등 사회통념상 문제가 되는 사행성 업종을 제외하고는 대다수의 업종이 정책 지원 대상이다. 업종과 더불어 투자 행위로 투자 심사를 해 신산업 투자에 매우 탄력적으로 운영할 수 있게 설계되어 있다. 심지어 미국의 경우, 적극적 창업 투자를 위해 업종 및 투자 행위에 대한 심의를 중소기업청이 직접 수행한다. 특히, 우리나라의 중소기업창업투자회사제도는 미국의 중소기업투자회사(SBIC) 제도와 유사한 반면 투자 제한 업종 뿐 아니라 제도 운영 특히, 창업투자회사에 대한 관리 측면에서 매우 큰 차이가 있음을 보여주고 있다. 우리나라 중기청은 간접관리를 하는 반면, 미국은 중기청 내에서 직접 관리를 하고 있다. 따라서 본 연구에서는 우리나라 창업 벤처 투자 제한을 미국을 비롯한 기타 외국의 사례에서와 같이 사회통념상 불가피한 업종과 더불어 투자 행위로 정의하길 제안한다.