• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.278-281
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• 2001

A fixed bed biofilm reactor filled with ceramic media were used to remove nitrogen by selective nitrification (ammonium to nitrite). The effects of experimental conditions (nitrogen load, dissolved oxygen, nitrite ratio, C/N ratio) on denitrification were investigated. The reactor showed more than 80% average T-N removal efficiencies at T-N loading in the range of $1.1{\sim}3.3$ kg $T-N/m^3{\cdot}d$ C/N at the C/N ratio of 1. T-N removal efficiencies increased as nitrite ratio.

• 한국방사선학회논문지
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• 제10권2호
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• pp.73-79
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• 2016

본 데이터 분석은 췌장의 묘출을 위한 2D T1 FFE 과 3D T1 THRIVE 기법을 비교하고자 하였다. 1.5 T에서 검사한 총 85명(남자 45명, 여자 40 명, 연령범위 38-80세, 평균연령 58세)의 데이터를 PACS 네트워크(network)로 분석을 하였다. 평균 2D T1 FFE(SNR: $46.42{\pm}0.67$, CNR: $28.16{\pm}0.50$)보다 3D T1 THRIVE(SNR: $53.84{\pm}1.20$, CNR: $35.48{\pm}0.70$)값이 의미 있게 높은 값을 보여주었고(p<0.05), 영상의 질적인면(2D T1 FFE: $2.2{\pm}0.05$, 3D T1 THRIVE: $2.63 {\pm}0.14$)에서도 2D T1 FFE 기법에 비해 3D T1 THRIVE 기법이 모두 우위의 값을 얻게 되었다(p<0.05). 그러나 3D T1 THRIVE 기법이 높은 값을 얻었지만 영상의 질을 감소시키는 몇 가지 인공물이 발생하였다. 결론적으로 1.5 T MRI 기기를 이용한 3D T1 THRIVE 기법이 SNR, CNR, 영상의 질적 측면에서 증가된 결과를 얻었다.

• Steel and Composite Structures
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• 제16권6호
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• pp.611-637
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• 2014

A single plate shear connection, or shear tab, is a very popular shear connection due to its merit in ease of construction and material economy. However, problems in understanding the connection behavior, both in terms of strength and ductility, have been well-documented. Suggestions or design model for single plate connections in AISC Design Manual have been altered several times, with the latest edition settling down to giving designers pre-calculated design strength tables if the connection details agree with given configurations. Results from many full-scale tests and finite element models in the past suggest that shear strength of a bolt group in single plate shear connections might be affected by yield strength of plate material; therefore, this research was aimed to investigate and clarify effects of plate yield strength and thickness on shear strength of the bolt group in the connections, including the validity of using a plate thickness/bolt diameter ratio ($t_p/d_b$) in design, by using finite element models. More than 20 models have been created by using ABAQUS program with 19.0- and 22.2-mm A325N bolts and A36 and Gr.50 plates with various thicknesses. Results demonstrated that increase of plate thickness or plate yield strength, with the $t_p/d_b$ ratio remained intact, could significantly reduce shear strength of the bolt group in the connection as much as 15 percent. Results also confirmed that the $t_p/d_b$ ratio is a valid indicator to be used for guaranteeing strength sufficiency. Because the actual ratio recommended by AISC Design Manual is $t_p/d_b$ + 1.6 (mm) for connections with a number of bolts less than six and plate yield strength in construction is normally higher than the nominal value used in design, it is proposed that shear strength of a bolt group in single plate connections with a number of bolts equal or greater than seven be reduced by 15 percent and the $t_p/d_b$ ratio be limited to 0.500.

• 산업기술연구
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• 제22권A호
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• pp.185-192
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• 2002

The performance of old and the new concrete construction depends upon bond strength between old and the new concrete. Current adhesive and strength measurement method ignores the effect of stress concentration from shape of specimens. Therefore, this research calculates stress concentration coefficient as the ratio of drilling depth to drilling diameter($h_s/D$), the ratio of overlay thickness to drilling diameter($h_0/D$), the ratio of steel disk thickness to drilling diameter(t/D), the ratio of overlay elastic modulus to substrate modulus($E_1/E_0$), the distance from core to corner border(L_$_{corner}$) and the distance between cores(L_$_{coic}$) vary. The finite element method is adapted to analysis The results from 'the F.E.M analysis are as follows. The stress concentration effects can be minimized when the ratio of drilling depth to drilling diameter($h_s/D$) is 0.20~0.25, the elastic modulus ratio($E_1/E_0$) is 06~1.0, and the ratio of steel disk thickness to drilling diameter(t/D) is 3.0. The overlay thickness, the distance from specimens to corner border(L_$_{corner}$), the distance between cores(L_$_{coic}$) almost do not affect to the stress concentration.

• 대한화학회지
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• 제10권4호
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• pp.149-152
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• 1966

鹽素置換 anisol과 chloral hydrate를 縮合하면 D.D.T 類의 合成에서와 같이 bis compound의 化合物이 生成될 것이고 D.D.T 系統의 化合物처럼 殺蟲能이 있으리라고 豫測되므로 4-chloro anisol 과 chloral hydrate를 縮合하여 生成物의 構造를 檢討하였던 바 2,2 bis(2-methoxy-5-chlorophenyl) 1.1.1-trichloroethane임을 確認하였으며 反應條件과 「국화꼬마수염진딧물」 및 「귤응애」에 대한 殺충能을 檢討한 結果 前報文$^{(67)}$에서 發表한 바 있는 化合物들의 殺蟲能에 比하여 5培나 强한 殺蟲能을 가졌다는 事實을 알았다.

• Steel and Composite Structures
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• 제45권5호
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• pp.749-766
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• 2022

This paper investigates the seismic performance of exposed RCFST column-base joints, in which the high-strength steel bars (USD 685) are set through the column and reinforced concrete foundation without any base plate and anchor bolts. Three specimens with different axial force ratios (n = 0, 0.25, and 0.5) were tested under cyclic loadings. Finite element analysis (FEA) models were validated in the basic indexes and failure mode. The hysteresis behavior of the exposed RCFST column-base joints was studied by the parametrical analysis including six parameters: width of column (D), width-thickness ratio (D/t), axial force ratio (n), shear-span ratio (L/D), steel tube strength (f_y) and concrete strength (f_c). The bending moment of the exposed RCFST column-base joint increased with D, f_y and f_c. But the D/t and L/D play a little effect on the bending capacity of the new column-base joint. Finally, the calculation formula is proposed to assess the bending moment capacities, and the accuracy and stability of the formula are verified.

• 정보저장시스템학회논문집
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• 제3권2호
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• pp.54-58
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• 2007

Using metal/Si materials as a recording layer, we have achieved good results for a SR disc (super resolution disc). Mainly by controlling metal composition and the ratio of metal to Si of recording layer, signal qualities were greatly enhanced. At the mark length of 75nm, the best CNR (Carrier to Noise Ratio) was about 45dB. Write power was reduced down to about 6.5mW. LFN (Low Frequency Noise) could also be reduced down to 14dB. Single tone pattern jitters for every mark whose length is from 2T through 8T were achieved to be below 10%. The readout signal was stable sustaining CNR>40dB during about 15,000 times reading. The so-called "3T-problem" could be avoided.

• 한국수산과학회지
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• 제8권1호
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• pp.7-10
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• 1975

제주도 고등어 자망어업의 주어기인 1974년 5월 28일부터 8월 31일까지 서귀포와 비양도근해어장에서 고등어 자망어구의 이망율에 관한 시험조업결과는 다음과 같다. 1. $X^2$ t 검정에 의하면 고등어 nylon-monofilament 자망 B형이 nylon-multifilament 자망 A형보다 이망성능이 우위하고 나망율비는 $m_A:m_B=1:1.8$이다. 2. 망목 75mm인 nylon-monofilament 자망 C형, D형이 망목 85mm인 nylon-monofilament 자망 E형 F형 보다 이망성능이 우위하고 이망율비는 $m_E{\cdot}F:m_C{\cdot}D=1:2.8$이다. 3. 망계 굵기가 120tex와 75tex이고 망목이 75m 및 85mm인 C, D, E, F, 형에서는 상호간의 우위는 모두 확인할 수 없었다.

• 한국전기전자재료학회논문지
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• 제14권9호
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• pp.720-725
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• 2001

In this study, Pb(La,Ce)Ti $O_3$ ceramics were manufactured for 20 MHz resonator application. Electromechanical coupling factor( $k_{t}$, $k_{t3}$, mechanical quality factor( $Q_{mt}$ , $Q_{mt3}$ and dydnamic range (D.R) of thickness vibration mode were measured as the variations of $\ell$/t(length/thickness) ratio of ceramic substrates. Mechanical quality factor( $Q_{mt3}$) and dynamic range of third overtone thickness vibration mode showed the highest value of 2,773 and 52.22dB at specimen S4($\ell$/t=12), respectively. The excellent temperature stability of resonant frequency suitable for resonator application was shown, regardless of thermal shock.k.ock.k.

• 대한기계학회논문집B
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• 제35권12호
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• pp.1309-1316
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• 2011

본 논문에서는 올리고-dT 자성입자와 측면방향 자기영동 기술을 기반으로 하는 초고속 RNA 추출칩을 소개한다. 센자성 와이어에 유도된 고구배자장에 의해 RNA가 결합된 올리고-dT 자성입자를 분리함으로써 용해된 혈액으로부터 고속으로 RNA를 추출하였다. 유속이 20 ml/h까지 자성입자를 80% 이상의 효율로 분리할 수 있었으며, 분리시간은 총 1분 이내였다. 추출된 시료로부터 단백질에 대한 RNA 흡광비율(absorbance ratio of RNA to protein: A260/A280)이 1.7 이상임을 확인하였고, 따라서 추출된 RNA가 매우 순수함을 보였다. 추출된 RNA를 사용하여 cDNA 합성과 PCR을 수행하였으며, 이로부터 개발된 초고속 RNA 추출칩이 적은 양의 시료만으로 간편하며 빠르고 정교한 RT-PCR을 수행하는데 실용적임을 확인하였다.