• Bulletin of the Korean Chemical Society
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• 제11권4호
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• pp.343-347
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• 1990

A thermal decomposition of the tert-butoxy radical has been studied in the gas phase over the pressure range of 1-200 torr at $413_{\circ}K$ using di-tert-butyl peroxide + trimethylsilane mixtures. The relative rate constants were obtained by studying the competitive reactions between tert-butoxy radical decomposition 4(t-BuO·→ CH_3COCH_3 + CH_3·)$ and hydrogen abstraction reaction from trimethylsilane $(t-BuO·+ HSi(CH_3)_3 → t-BuOH + Si(CH_3)_3)·).$ The conventional RRKM calculations were carried out to compare the observed fall-off behavior of the decomposition rate constant $({\kappa}_d)$ with the theoretical predictions using reasonable values of input parameters. In all cases the calculated half-rate pressure $(P_{1/2})$ were significantly higher than those observed. The failure of RRKM to reproduce the fall-off behavior led us to suggest that not all of vibrational modes contribute to excitation (leading to decomposition) on the same time scale.

• 한국정밀공학회지
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• 제20권1호
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• pp.196-204
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• 2003

Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions such as seismic loading are required to provide appropriate safety assessment to these mechanical structures. The split Hopkinson Pressure Bar (SHPB) technique with a special experimental apparatus can be used to obtain the material behavior under high strain rate loading conditions. In this paper, dynamic deformation behaviors of the aluminum alloys such as A12024-T4, A16061-T6, and A17075-T6 under both high strain rate compressive and tensile loading conditions are determined using the SHPB technique.

• 대한후두음성언어의학회지
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• 제12권1호
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• pp.55-60
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• 2001

Background and Objectives : Syllable Maximum Repetition Rate(MRR) is ability to repeat rapidly the articulators and is assessed for oromechanism function as one of the MPT. MRR is measured by rate(counts/sec), also simultaneously considered accuracy and consistency. The objective of the present was to examine stimuli effects and age and sex differences for MRR. Materials and Method : This study was participated 60 normal males and females(1 : 1) who were divided into two groups young(<40 years old) and old($\geq$40 years old). Stimuli were $/{P^=}a/,/{t^=}a/,/{k^=}a/,/{P^h}a/,/{t^h}a/,/{k^h}a/,/{P^=}{at^=}{ak^=}a/$ for, manner(tense and aspirated) of articulation, $/{p^h}{at^h}{ak^h}a/,/{t^h}{ap^h}{ak^h}a/$ for the effect of the order of syllable, glide /u-i/ for coordination of lip and tongue, interrupted vowel /i/ for laryngeal function. Results : There were little differences in two age groups and sex and manner of articulation for MRR tasks. The fastest average MRR of the single syllable included in this study was $/{t^=}a/$. significant differences existed between MRR for ${p^h}{at^h}{ak^h}a/ and /{t^h}{ap^h}{ak^h}a/$, which suggested that MRR was affected by the order of the syllables. MRR for interrupted vowel /i/ was about 2 counts/sec slower than average rate of 1 syllables. Conclusion : From these results, the order of the syllables was a crucial variable in MRR. rather than age or sex. There were no difference age, sex and manner of rate. The interrupted vowel repetition rate was slightly slow used and can provide basic information to assess the speech mechanism and can be useful to develop effective stimuli to differentiate the disordered group from normal.

• Parasites, Hosts and Diseases
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• 제35권3호
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• pp.155-164
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• 1997

경북지역에 있어서 간흡충 감염상의 변화를 1993년 5월부터 1995년 4월가지 주민을 대상으로 간흡충 항윈피내반응과 충란검사를 할과 아울러 제2중간숙주인 담수어에서의 본 충 피낭유충 기생 상을 조사하였다. 주민들에 있어서 간흡충 감염률은 7 .7%로 비교적 높았으며. 남성에서 11.3% 여성에서 4.1%로 유의적 차를 인정할 수 있었다. Catalytic model의 특이형을 적용하였던 바. 관측치로부터 얻어진 이론곡선은 남성에서 y = 0.4776($1{\;}-{\;}e^{-0.0375t}$). 여성에서 y = 0.2085($1{\;}-{\;}e^{-0.0138t}$)이었다. Muench의 two-stage catalytic model로 연령별 감염률을 추정하여 y = 0.025($1{\;}-{\;}e^{-0.047t}{\;}-{\;}e^{-0.0235t}$). 즉, 매년 간흡충 감염자는 주민 1.000명에 대괘 4.7명의 비율로 산출되며 감염자 1,000명 중 23.5명의 비율로 음성으로 전환되고 있음을 알 수 있었다 간흡충 감염자에 있어서 EPG의 cumulative percentage와 Bliss의 probittable를 이용하여 회귀방정식을 계산하였던 바. 남자에서 y : 0.929 + 1.506 logx. 여자에서 y : 0.473 + 1.767 logx이었다. 채집된 9과 25종의 어류 중 7종에서 간흡충 피낭유충을 검출할 수 있었으며. 평균 감염량이 참붕어에서는 58.1개로 가장 많았고, 다음은 10.2개인 몰개였으며 납지리 및 두우쟁이에서는 각각 3.6 및 7.0개이었다. 이상의성적으로 미루어 보아 경북 지역의 간흡충증은 수십년전에 비해 적게 유행되고 있으며 계속 감소하고 있음을 확인하였다.

• 한국가금학회지
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• 제10권2호
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• pp.91-96
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• 1983

본시험은 산란노계의 인공수정에 있어서의 적정주정간격을 구명하기 위하여 실시하였다. 580일령 백색레그혼 수탉 20수, 530일령 갈색실용산란계암탉 120수를 공시하였으며, 시험기간중의 평균산란율은 61.6%이었고 공시란은 2,283개이었다. 주정간격 T$_1$ 2일, T$_2$, 4일, T$_3$ 6일의 3개 처리구를 설정하여 혼합정액을 1회 0.03$m\ell$씩 주입하였다. 6일마다 알을 수집, 부화 5일만에 투시검란하였던 바 시험결과를 요약하면 다음과 같다. 전시험기간중의 주정간격별 평균수정율은 T$_1$(2 일) 87.5%, T$_2$(4 일) 81.1%, T$_3$(6 일)65.1%로서 T$_1$과 T$_3$, T$_2$와 T$_3$ 사이에 5% 수준의 유의차가 인정되었다. 주정후의 일별수정율의 평균은 각구 모두 주정 후 제2일이 가장 높아서 T$_1$, 90.7%, T$_2$, 84.0%, T$_3$, 71.7%이었으며, 그 이후는 점진적으로 조금씩 떨어지는 경향을 보였다. 본시험결과를 종합컨대 노산란계에 있어서의 적정주정간격은 2일이라 하겠으며, 전반적으로 주정회수를 거듭함에 따라 수정율이 점증하였는데 2일간격 주정의 경우 최고수준의 수정율(98.2%)에 도달하는 주정회수는 6회차 이었다.

• 대한소아치과학회지
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• 제8권1호
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• pp.15-19
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• 1981

As a pilot survey of Water Fluoridation in Chungju, Fluoride content in the water of that city was examined, and 1563 K primary school children aged from 7 to 13 were surveyed on their oral hygiene status. The results were as followings: 1. Fluoride content...0.1 ppm. 2. dmf rate...80.04 % DMF rate...45.17 % 3. dmf t rate/index...28.29 % / 2.18 dmf s rate/index...14.14 % / 5.44 4. DMF T rate/index...6.62 % / 1.07 DMF S rate/index...1.87 % / 1.51.

• 대한가정학회지
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• 제23권1호
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• pp.11-17
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• 1985

This paper aims to examine the variety of the absorption of cotton, T/C and hemp fabrics seperately seperaterly sized by rice, wheat, potato, corn flour and pp.V.A.. Experimental variables occurring in the concentration of sizing agents, the water content of unsized fabrics and an iron temperature show the following results, 1. When fabrics sized, the rate of absorption increases according to the order of rice, corn, pp.V.A., potato, wheat flour for cotton fabrics, of rice, corn, pp.V.A., wheat, potato flour for hemp fabrics and of the rice, pp.V.A., potato, corn, wheat flour for T/C fabrics : rice flour shows an absorption rate highest among all the others mentioned above. 2. To a certain extent, the stronger the concentration of sizing agents, the higher the rate of absorption. 3. The higher fabrics density, the higher absorption rate. 4. The structure and hydrophilic property of the sized fabrics affect the rate of absorption. 5. The fabrics with water content of 20% before sizing it shows the rate of absorption highest. 6. An iron temperature after sizing fabrics shows the rate of absorption highest at the properest at the properest one : $180^{\circ}C$ for cotton, $150^{\circ}C$ for T/C and $200^{\circ}C$ for hemp fabrics.

• 대한방사선기술학회지:방사선기술과학
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• 제41권2호
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• pp.103-107
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• 2018

In MR, the iodine CT contrast medium reduces the T1 and T2 relaxation times of the substance, resulting in a change in signal intensity. This study aimed to measure the relaxation rate of MR contrast medium with or without diluting CT contrast medium and analyzed the effect of CT contrast medium. Undiluted Gadoteridol solution was diluted with saline to prepare MR contrast medium phantoms with various levels of Gadoteridol concentrations. Moreover, undiluted Iomeprol was mixed with the prepared MR contrast medium phantoms at 1:1 ratio to make MR contrast medium phantoms with containing CT contrast medium for the experiment. T1 and T2 mappings were conducted to quantitatively evaluate the relaxation time and relaxation rate of these phantoms. The results showed that the T1 and T2 relaxation time and relaxation rate of MR contrast medium diluted with CT contrast medium were significantly (p<0.05) shorter than those of MR contrast medium not diluted with CT contrast medium. The results of this study imply that, when MR contrast medium shall be used after injecting CT contrast medium, CT contrast medium should be discharged enough. Moreover, it would be desirable to conduct CT test after taking MRI test in order to reduce the effects of CT contrast medium on MR contrast medium.

• 한국환경보건학회지
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• 제35권1호
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• pp.64-70
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• 2009

The aims of this study is to examine the effects of the changes in HRT(Hydraulic Retention Time) and media charge in a water-mill, among other operation factors, on the nitrogen and phosphorus removal in order to use up-flow anaerobic reactors, anoxic reactors and water-mill aerobic reactors for sewage treatment. The extension of HRT improved the nitrogen removal efficiency, however the removal pattern was constant regardless of HRT. The removal of phosphorus was constant (80%-90%) regardless of the change in HRT. The removal rate with change in influx load varied such that at the OLR (Organic Load Rate) of 1-3 kg/d, the T-N removal efficiency was 80.7%-88.9% and the T-P removal efficiency was 82.9%-89.3% while at the NLR (Nitrogen Loading Rate) of 0.108-0.156 kg/d the removal efficiencies were 80.7-88.9% (T-N) and 82.9-89.3% (T-P). The analyses of the nitrogen and phosphorous removal characteristics with the C/N and C/P ratio showed that the mean T-N removal rate was 88% at the C/N ratio of 1.2-2.6, and that the mean T-P removal rate was 86% at the C/P ratio of 7.2-14.1. Also, the analysis of nitrogen and phosphorous removal characteristics were analyzed in relation to media charge. The comparison between with and without media charge in the water-mill showed that while the nitrogen removal efficiencies were 86-94% and 85-89% respectively, the difference of phosphorous removal efficiencies were between the two conditions was not significant, thus it suggested that the media charge has less effect on the removal efficiency of phosphorous compared to that of nitrogen.

• 한국수산과학회지
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• 제14권4호
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• pp.253-259
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• 1981

어획대상 자원에 있어서 감소계수를 z, 완전가입 년령을 a, 최고년령을 b라 할 때 체장조성과 성장곡선식을 이용해서 감소계수 z를 구하는 수학적 모형을 설정하여 고등어와 전갱이의 생잔율을 추도한 결과를 요약하면 다음과 같다. 1. 평균년령을 $U_t$라 하면 a, b, z 및 $U_t$의 관계식은 $$U_t=\frac{a-b ex p[-z(b-a)]}{1-ex p[-z(b-a)]}+\frac{1}{z}$$이다. 2. 성장곡선식을 사용하여 체장조성표의 각 체장계급에 해당하는 년령을 추정하고 전계급에 걸친 평균년령을 계산하였다. 3. $U_t$값을 a, b, z 및 $U_t$와의 관계식에 대입하여 감소계수 z값을 구하고 생잔율 exp(-z) 값을 구하였다. 4. 한국 연안 (제1해구)산 고등어와 전갱이의 감소계수, 생잔율 및 생잔율의 $95\%$ 신뢰구간을 계산한 결과는 고등어가 0.87909, 0.41516, 0.35966-0.47264 전갱이가 2.22327, 0.10825, 0.06897-0.14974이었다.