• 한국공작기계학회논문집
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• 제11권1호
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• pp.52-60
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• 2002

The purpose of this research is to study the vibration and acoustic pressure radiation from a thin isotropic flat plate stiffened by a rectangular array of beams, and excited by a time harmonic point force. These constructions on aircraft and ship structures are often subjected to fiequency dependent pressure fluctuations and forces. Forces from the these excitations induce structural vibrations in a wide range of fiequencies, which may cause such things as acoustic fatigue and internal cabin noise in the aircraft. It is thus important that the response characteristics and vibration modes of such periodic structures be horn. From this theoretical model, the sound pressure levels(SPL) in a semi-infinite fluid(water) bounded by the plate with the variation in the locations of an external time harmonic point farce on the plate can be calculated efficiently using three numerical tools such as the Gauss-jordan method the LU decomposition method md the IMSL numerical package.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1073-1077
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• 2001

The objective of this paper is to apply an experimental method based on the principle of reciprocity to measuring the structural intensity. Since only one accelerometer is used in this method it has the advantages of shortening measurement time. reducing accelerometer phase error. overcoming the limitation that the situation should be stationary during the experiment. It has been used to measure the vibration intensity of an infinite beam (beam with damped ends) and a semi-infinite beam (beam with simply supported and damped ends). Results showed that the experiment method based on the principle of reciprocity can be effectively used to measure the structural intensity.

• 공업화학
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• 제10권5호
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• pp.672-676
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• 1999

흡착을 이용한 분리공정에서 가장 기본적인 것은 흡착평형식이다. 본 연구에서는 용출곡선법과 frontal analysis(FA)을 사용하여 용출곡선에서 직접 흡착평형식을 구하였다. 역상 액체 크로마토그래피(RP-HPLC)에서 시료는 5'-GMP이고 buffer로서 sodium phosphate를 물에 첨가하여 이동상으로 사용하였다. 이 실험조건에서는 시료의 양이 증가함에 따라서 체류시간이 감소하고 피크의 앞부분이 매우 경사가 심한 Langmuir 흡착평형식이 되었다. 용출곡선을 이용한 방법을 이용하여 Langmuir 흡착평형식의 매개변수를 최적화하여 구하였고 FA 방법을 이용하여 고정상의 농도를 용출곡선으로부터 측정하고 회귀분석에 의하여 흡착평형식을 측정하였다. FA 방법에 비해서 용출곡선법은 시료의 양이 적게 소모되고 실험 횟수도 1-2번 정도로 간편하였다. 이동상에 포함된 sodium phosphate의 농도에 따라서 Langmuir 흡착평형식의 매개변수에 미치는 영향을 고찰하였다.

• 한국잠사곤충학회지
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• 제33권1호
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• pp.32-36
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• 1991

해충의 미생물적 방제를 위하여 Bacillus thuringiensis 살충제 개발에 관한 기초자료를 얻고자 3종의 B. thuringiensis var. kurstaki, dendrolimus, aizawai를 이용하여 배지내에서 생장특성을 조사하고 이들의 내독소단백질의 분리를 위해 Renograffin 불연속중층법을 이용한 새로운 분리법을 시도하였다. 1. 각공시균주의 생장곡선을 조사한 결과는 3균주 모두 접종후 3시간 이내에 exponential phase에 이르렀고, 7-8시간 정도에서 stationary phase에 이르렀다. 2. 배지내 pH변화는 exdponential phase때 원래 배지에서 1.4정도 저하하였다가 sporulation의 개시에 따라 회복되기 시작하여 후기에 거의 평형상태를 나타내서 균주간에 차이가 없는 것으로 확인되었다. 3. Renograffin 불연속중층법을 이용한 새로운 B. thuringiensis 내독소단백질 분리법은 50$m\ell$ 원심분리관에 10$m\ell$의 시료를 중층, fixed angel rotor를 이용하여 27,000g에서 1시간 원심했을 경우 99.0% 순도와 5.8%의 회수율을 나타내어 지금까지 보고된 방법들보다 더욱 효율적인 것으로 확인되었다.

• Archives of Pharmacal Research
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• 제24권5호
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• pp.407-411
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• 2001

Reversed-phase high performance liquid chromatographic method was applied for the determination of eleutheroside B and E in the various Acanthopanax species collected In Korea. The stationary phase used was Zorbax 300 SB $C_{18}$ and a mobile phase program was used, which started at 6% acetonitrile for 2 min, and then a linear gradient was operated for the next 18 min to 17% acetonitrile at a flow rate of 1.0 ml/min. The column effluent was monitored at UV 210 nm. Identification was carried out by comparing the retention time and the LC/MS spectrum of each peak corresponding to eleutheroside B and E from sample with those of standards. In general, the contents of eleutheroside B and 1 in stems were higher than those In roots. Acanthopanax species could be classified into two groups based upon the contents of eleutheroside B and E: one group contains no or very little eleutheroside B and another contains both eleutheroside B and E.

• 약학회지
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• 제43권3호
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• pp.300-305
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• 1999

A sensitive and efficient assay method was applied to determine the level of glutamic acid (GA) and ${\gamma}-aminobutyric$ acid (GABA) in frontal cortex and hippocampus of rat administrated with ethanol and drugs. The compounds were derivatized with ο-phthalaldehyde (OPA) and 2-mercaptoethanof for precolunm analysis. The condition for the simultaneous determination of GA, GABA and $\beta-aminobutyric$ acid (BABA) by high performance liquid chromatography with electrochemical detection was reverse phase $C_{18}$ column as stationary phase, 0.1 M phosphate buffer containing 0.1 mM $Na_4EDTA$ : methanol = 55:45 (v+v) pH 3.8 as mobile phase and 0.7V electrode voltage. The stability of reaction product of GA, GABA and BABA with OPA could be increased by adding the same volume of polyethylene glycol 400 to reaction mixture. The GABA level in frotal cortex of rat was significantly decreased by the administration of picrotoxin and diazepam, but it was significantly increased by the administration of red ginseng total saponin, N-methyl-D-glucamine and (-)-deprenyl.

• 대한화학회지
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• 제34권1호
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• pp.76-84
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• 1990

키랄이동상 첨가법으로 단실아미노산의 광학이성질체들을 분리했다. 두 가지의 xylenyl-L-proline 이성질체를 합성하고 이것을 구리(Ⅱ)킬레이트로 만들어 이동상에 첨가하여 단실아미노산의 광학 이성질체를 분리했다. 이 아미노산에 대한 용리거동은 benzyl-L-proline의 구리착물을 사용했을 때와 유사했다. 이동상에서 유기용매의 조성, 완충용액의 농도 및 pH에 대한 효과도 조사 검토했다. 분리메카니즘은 리간드 교환반응의 시스-트란스 효과의 삼성분착물과 정지상간의 소수성 상호작용으로 설명할 수 있었다.

• Archives of Pharmacal Research
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• 제27권10호
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• pp.1009-1015
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• 2004

Quantitative Structure-Resolution Relationship (QSRR) using the Comparative Molecular Field Analysis (CoMFA) software was applied to predict the chromatographic behaviors of chiral drugs with an amine moiety on the chiral cellobiohydrolase (CBH) columns. As a result of the Quantitative CoMFA-Resolution Relationship study, using the partial least square method, prediction of the behavior of drugs with amine moiety upon chiral separation became possible from their three dimensional molecular structures. When a mixed mobile phase of 10 mM aqueous phosphate buffer (pH 7.0) - isopropanol (95 : 5) was employed, the best Quantitative CoMFA-Resolution Relationship, derived from the study, provided a cross-validated $q^2$ = 0.933, a normal $r^2$ = 0.995, while the best Quantitative CoMFA-Separation Factor Relationship, also derived from the study, yielded a cross-validated $q^2$ = 0.939, a normal $r^2$ = 0.991. When all of these results are considered, this QSRR-CoMFA analysis appears to be a very useful tool for the preliminary prediction on the chromatographic behaviors of drugs with an amine moiety inside chiral CBH columns.

• Natural Product Sciences
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• 제15권3호
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• pp.144-150
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• 2009

Gradient centrifugal partition chromatography (GCPC) method was developed and applied to isolate 3,5-dimethoxyphenanthrene-2,7-diol (DMP) and batatasin-I (BA-I) from the dichloromethane soluble extract of Dioscorea opposita. In this method, the lower phase of n-hexane-methanol-water system (HMW, 10 : 9 : 1, v/v) was used as a mobile phase A (MpA) and water was used as a mobile phase B (MpB). This gradient CPC method is comparable to that of reversed-phase HPLC method in that the stationary upper-phase of HMW (10 : 9 : 1 v/v) works as if it were reversed-phase silica gel due to its hydrophobic property, while the lower phase (MpA) and water (MpB) functioned as hydrophilic mobile phases. The initial condition of the mobile phase was 20% MpA/80% MpB and maintained for 150 min to obtain DMP (1.2 mg), and then MpA was increased up to 50% to elute BA-I (1.7 mg). The purities of DMP and BA-I were 94.1% and 98.3% with the recovery yields of 83% and 86%, respectively. Similar results were obtained by linear-gradient CPC. The CPC peak fractions were identified by comparing their retention time to those of authentic samples of DMP and BA-I and their spectroscopic data ($^1$H NMR and $^{13}$C NMR) to those of literature values.

• 대한기계학회논문집
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• 제12권2호
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• pp.193-199
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• 1988

본 연구의 목적은 SCPA방법을 이용한 비선형 2자유도 비감쇠계의 해석을 통하여 응답곡선을 구하고, 그 응답곡선의 분기현상을 규명함에 있다. 결과의 비교를 위하여 4차의 Runge-Kutta방법을 이용한 수치실험을 수행하였다.