• Proceedings of the Korean Environmental Health Society Conference
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• 2001.11a
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• pp.42-48
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• 2001

A kinetic model was presented to estimate the uptake/release rate constants and thereafter, bioconcentration factor, $k_1$, $k_2$ and BCF (bioconcentration factor), for the uptake of PH by plankton were obtained. Implies that PH(petroleum hydrocarbon) caused no significant influence on the uptake of $N-NO_3$, but significant influence on that of $P-PO_4$. In addition, the application of kinetic model for the bioconcentration of volatile organic toxic compound by organism suggests that the uptake of PH by plankton was an important process for the environmental capacity of PH.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.196-199
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• 1996

In this paper, aging characteristics of outdoor silicone rubber insulator resulting from the acid rain have been investigated with regards to nitrate ion ($NO_3$). For this purpose, silicone rubber was aged by immersing into the nitric solutions with different level ph during 1500 hours and various tests(tracking, contact angle, $tan{\delta}$, breakdown voltage, SEM, EDS, FT-IR) were performed. It was observed that the degradation was increased to ph 2.5 slightly and highly at ph 1.5. And thus, it could be expected that there is certain critical point between ph 1.5 and 2.5, which leads to throught degradation.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.172-172
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• 2000

진공상태에서 diamond stylus로 MgO 표면을 마모시킬 때 발생되는 photon, electron과 마찰력을 시간의 함수로 동시에 측정하였다. 전자 방출(EE)은 Channeltron electron multiplier로 , 광자 에너지는 Photomultiplier tube를 사용하여 측정하였는데 180~600nm 영역의 photon을 검출하였다. 광자 방출(PhE,) 실험은 공기중에서도 할 수 있으나 전자방출은 1$\times$10-4pa 이하의 진공에서 실험하여 얻었다. 본 실험을 통하여 결정과 diamond stylus 사이에서 일어나는 마모 현상은 millisecond로 관찰하여 표면 변화에 대한 상관관계를 조사하였다. 열처리 한것과 열처리 하지 않은 시료를 비교한 결과 3개의 signal(마찰력, PhE, EE)을 시간에 따라 분석하면 stick-slip-like 현상을 볼 수 있었다. 이것으로 보아 stick은 변형에 의해 생기고 ms 후에 벽개 현상이 발생됨을 볼 수 있다. 방출과 마찰력은 표면조건, load, stylus velocity에 따라 변하였다. luminescence는 주로 변형에 의해 생겼으며, 전자 방출은 벽개(fracture)에 의해 발생됨을 알 수 있었다. 시료의 처리과정과 load 속도에 따른 Photon, electron의 방출은 시료의 표면 상태에 따라 좌우되었다. 마찰력, PhE, EE의 시간에 따른 분석에서 PhE는 변형 과정에 민감하며, EE는 stylus velocity에 의존하였다. 이러한 방출 현상은 세라믹의 급격한 벽개 과정을 이해하는데 많은 도움을 주었다.

• Journal of Technology Innovation
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• v.7 no.1
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• pp.124-150
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• 1999

This study examines the personal characteristics, organizational attitudes, technical performances, and reward preferences of R&D professionals with Ph.D. degree in large private companies in Korea. Based on survey data from 887 professionals in nine different R&D organizations, the following results are found; 1) R&D professionals with Ph.D. degree exhibit higher autonomy preference, need for achievement, self-efficacy, technical career orientation, and performance proficiency than other R&D professionals; 2) As their organizational tenure increases, performance proficiency and transfer career orientation increases but their socialized level of organizational goals and values does not change; 3) They produce more technical publications and exhibit more positive organizational attitude than other R&D professionals; 4) They are more likely to prefer job content, professional, and job security rewards. These empirical findings suggest several theoretical and practical implications for the management of R&D professionals with Ph.D. degree in the large Korean firms.

• Bulletin of the Korean Chemical Society
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• v.20 no.4
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• pp.427-430
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• 1999

The Grignard coupling reaction of bis(chloromethyl)diorganosilanes [(ClCH2)2SiR1R2: R1 = R2 = Me, la; R1 = Me, R2 = Ph, lb; R1 = R2 = Ph, lc] with diorganodichlorosilanes [(Cl2SiR3R4: R3 = R4 = Me, 2a; R3 = Me, R4 = Ph, 2b; R3 = R4 = Ph, 2c] at THE reflux temperature gave the intermolecular C-Si coupling product of 1,1,3,3-tetraorgano-1,3-disilacyclobutanes 3a-f in poor to moderate yields ranging from 7% to 50% along with polydiorganosilapropanes. The cyclization reaction of la-c with methyl-substituted dichlorosilanes 2a, b gave 1,3-disilacyclobutanes 3a-c, e, d in moderate yields (42-50%), while the same reaction with dichlorodiphenylsilane (2c) to 1,3-disilacyclobutanes 3d, f resulted in low yield (7-18%) probably due to the steric hindrance of two-phenyl groups on the silicon of 2c.

• Bulletin of the Korean Chemical Society
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• v.13 no.4
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• pp.429-440
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• 1992

The second order ab initio effective valence shall Hamiltonian ($H^v$) which is based on quasidegenerate many-body perturbation theory is applied to the SiH, PH, and their positive ions. A singie Hv computation for the neutral molecule is used for a whole set of valence states of a molecule and its ion simultaneously. The low-lying valence state potential energy curves of SiH, PH and their positive ions are computed. And various spectroscopic constants of the low-lying bound valence states are determined from the potential energy curves. The $H^v$ results are found to be in good agreement with other theoretical and experimental data.

• Bulletin of the Korean Chemical Society
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• v.17 no.6
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• pp.532-535
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• 1996

The bulk photopolymerization of methacrylic acid (MA) with secondary silanes such as PhMeSiH2 and Ph2SiH2 gave poly(MA)s possessing the secondary silyl moiety presumably as an end group. It was found that while the polymerization yields and intrinsic viscosities decreased, the TGA residue yields and the relative intensities of SiH IR stretching bands increased with increasing mole ratio of the secondary silane over MA. The sterically less bulky silane PhMeSiH2 produced poly(MA)s with somewhat higher molecular weights and with similar TGA residue yields compared with the sterically bulkier silane Ph2SiH2. The secondary silanes seem to significantly influence on the photopolymerization of MA as both chain initiation and chain transfer agents.

• Journal of Cardiovascular Imaging
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• v.26 no.4
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• pp.189-200
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• 2018

Pulmonary hypertension (PH) is defined as resting mean pulmonary artery pressure ${\geq}25mmHg$ and is caused by multiple etiologies including heart, lung or other systemic diseases. Evaluation of right ventricular (RV) function in PH is very important to plan treatment and determine prognosis. However, quantification of volume and function of the RV remains difficult due to complicated RV geometry. A number of imaging tools has been utilized to diagnose PH and assess RV function. Each imaging technique including conventional echocardiography, three-dimensional echocardiography, strain echocardiography, computed tomography and cardiac magnetic resonance imaging has-advantages and limitations and can provide unique information. In this article, we provide a comprehensive review of the utility, advantages and shortcomings of the multimodality imaging used to evaluate patients with PH.

• International journal of advanced smart convergence
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• v.11 no.2
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• pp.30-37
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• 2022

Because fine dust (PM10) has a close effect on the environment, fine dust generated in the climate and living environment has a bad effect on the human body. In this study, the LSTM model was applied to predict and analyze the effect of fine dust on Gwangju Metropolitan City in Korea. This paper uses prediction values of input variables selected through correlation analysis to confirm fine dust prediction performance. In this paper, data from the Gwangju Metropolitan City area were collected to measure fine dust. The collection period is one year's worth of data was used from january to December of 2021, and the test data was conducted using three-month data from January to March of 2022. As a result of this study, in the as a result of predicting fine dust (PH10) and ultrafine dust (PH2.5) using the LSTM model, the RMSE was 4.61 and the test result value was as low as 4.37. This reason is judged to be the result of the contents of the one-year sample.

• Proceedings of the KWS Conference
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• 1996.10a
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• pp.89-91
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• 1996