• Archives of Pharmacal Research
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• 제11권3호
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• pp.225-229
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• 1988

A ginseng protein fraction which has been reported to have radiation protective effect was purified from Korean ginseng and its effects on relative survival and chromosome aberration were studied in UV irradiated CHO-K1 cells. When the protein fraction $(100\;{\mu}g/ml)$ was added to the cells before UV irradiation at 4\;J/$m^2$,, the survival rates were increased to 53.8% from 40.6% in control. Addition of the protein $(100\;{\mu}g/ml)$ after UV irradiation at 4 and $8\;J/m^2$ raised the rates to 85.4 and 24.0% from 79.2 and 11.5% in control, respectively. When the ginseng protein $(800\;{\mu}g/ml)$ was added to the cells exposed to UV light at 10, 20, $30\;J/m^2$, the frequencies of chromosome aberration (CA) were reduced significantly to almost same level regardless of the UV dose increment and there was no significant difference between pre- and post-treatment. When the concentration of ginseng protein was increased from 200 to $800\;{\mu}g/ml$, at UV dose of 10, 20, $30\;J/m^2$ each, the CA frequencies were decreased consistently as the dose of ginseng protein increased, at all UV doses tested. Similar effects were observed in both cases of pre- and post-treatment. The data suggest that the protein may reduce cell damage caused by UV light, especially damage to DNA molecule, or play a role in repair processes of damaged DNA, to increase cell survival and reduce chromosome aberrations.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.337-345
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• 2002

The equilibrium structures for the ground and transition states of $C_7H_7^+$ isomers have been investigated using sophisticated ab initio quantum mechanical techniques with various basis sets. The structures of tropyrium and benzyl cations have been fully optimized at the DZP CCSD(T) levels of theory. And the structures of o-, m-and p-tolyl cations are optimized fully up to the DZ CCSD(T) levels of theory. The geometries for the transition states between three isomers of tolyl cations have been optimized up to DZP CISD level of theory. The SCF harmonic vibrational frequencies for tropylium, benzyl, and three isomers of tolyl cations are all real numbers, which confirm the potential minima and each unique imaginary vibrational frequencies for TS1 and TS2 confirm the true transition states. The relative energy of the benzyl cation with respect to the tropyrium cation is predicted to be 28.5 kJ/mol and is in good agreement with the previous theoretical predictions. The 0 K heats of formation, ${\Delta}H^{\circ}_{f0}$, have been predicted to be 890, 1095, 1101, and 1110 kJ/mol for tropylium, ortho-, meta-, and para-tolyl cations by taking the experimental value of 919 kJ/mol for the benzyl cation as the base level. The relative stability between tolyl cations is in the order of ortho

• 대한수의학회지
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• 제32권3호
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• pp.281-293
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• 1992

Classification of the cycle of seminiferous epithelia into 12 stages by the morphological changes in acrosomal system and evaluation of the relative frequency of stages and the cell association were histologically performed in the mature Korean native Jin-do dogs. The results were summarized as follows; 1. The minimum number of type A spermatogonia averaged 1.01 at stages I, while maximum number averaged 2.47 at stages XII. Some type A spermatogonia divided at stage XII to produce the type intermediate(IN) spermatogonia at the following stage I. The type IN spermatogonia divided at stage IV to produce the type B spermatogonia at stage V. 2. The type B spermatogonia divided at stage VI to produce the preleptotene primary spermatocytes at stage VII. The secondary spermatocytes observed at stage XII. The secondary spermatocytes observed at stage XII divided to give rise to the round spermatids at the following stage I. The numbers of the first spermatocytes and spermatids were almost constant, respectively, through all the cycles of seminiferous epithelium. 3. The acrosomal vesicle was invaginated to occupy one third to half of spermatid nucleus at the cap phase, which was different from that of rodent and ruminant spermatid nuclei. 4. The relative frequencies of stages I to XII of seminiferous epithelia cycle were 10.34, 4.84, 5.03, 8.22, 10.86, 6.63, 6.42, 18.88, 10.17, 6.18, 7.62% and 4.81%, respectively.

• 한국음향학회지
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• 제21권5호
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• pp.446-454
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• 2002

본 연구는 이동 표적체에서 주파수가 서로 다른 신호가 서로 다른 위치에서 발생할 때 도플러 주파수 편이량을 추정하여 이들의 상대적인 신호 발생 위치를 추적하는 도플러 스캐닝 기법에 관한 연구이다. 예를 들어 선박의 발전기와 프로펠러 등과 같은 탑재 기계장치들의 진동에 의해 야기되는 기계적 소음의 각 특징 주파수들의 도플러 주파수 편이는 최단근접거리 (CPA: Closest Point of Approach)에 따라 유일한 시간 정보를 갖고 각 소음원들의 위치에 관련되는 함수이다. 따라서 도플러 스캐닝 기법을 적용하면 이동 선박의 각 기계적 소음원들간의 공간적인 상대 위치 추정이 가능하다. 그러나 일반적으로 기계류 소음의 주파수는 저주파수대역이므로 도플러 주파수 편이량을 추정하기 위해서는 주파수 분해능이 높아야 하고 아울러 탑재장치의 공간분해능을 높이기 위해서는 동시에 시간 분해능이 높아야 한다. 따라서 상호 역비례 관계에 있는 이들 분해능을 동시에 높이기 위해 확장 칼만 필터 알고리즘을 적용하여 특징 신호들의 도플러 주파수 편이량을 추정하여 기계류의 상대적인 탑재 위치를 규명할 수 있음을 보인다. 먼저 수치모의 실험으로 그 가능성을 검증하고 자동차에 탑재된 스피커 음원을 사용한 실험 결과를 통해 그 성능을 확인하도록 한다.

• Wind and Structures
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• 제11권1호
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• pp.35-50
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• 2008

Wind and temperature have been shown to be the critical sources causing changes in the modal properties of large-scale bridges. While the individual effects of wind and temperature on modal variability have been widely studied, the investigation about the effects of multiple environmental factors on structural modal properties was scarcely reported. This paper addresses the modeling of the simultaneous effects of wind and temperature on the modal frequencies of an instrumented cable-stayed bridge. Making use of the long-term monitoring data from anemometers, temperature sensors and accelerometers, a neural network model is formulated to correlate the modal frequency of each vibration mode with wind speed and temperature simultaneously. Research efforts have been made on enhancing the prediction capability of the neural network model through optimal selection of the number of hidden nodes and an analysis of relative strength of effect (RSE) for input reconstruction. The generalization performance of the formulated model is verified with a set of new testing data that have not been used in formulating the model. It is shown that using the significant components of wind speeds and temperatures rather than the whole measurement components as input to neural network can enhance the prediction capability. For the fundamental mode of the bridge investigated, wind and temperature together apply an overall negative action on the modal frequency, and the change in wind condition contributes less to the modal variability than the change in temperature.

• 한국음향학회지
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• 제28권3호
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• pp.222-228
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• 2009

본 논문에서는 편종의 조율 방안을 모색하기 위하여 유물 편종과 현대 편종의 음향 스펙트럼을 비교분석하였다. 유물 편종은 세종대왕기념관에서 소장하고 있는 편종을, 현대 편종은 국립국악원에서 연주되는 편종을 사용하였다. 음향 스펙트럼과 TV 홀로그래피를 이용한 모드분석을 통해 현대 편종의 모드진동수와 모드형상을 파악하였다. 유물 편종의 경우는 음향 스펙트럼 분석만 하였다. 각각의 음고에 해당하는 현대 종과 유물 종의 기명진동수는 9.8 센트부터 203 센트까지 차이를 나타냈다. 유물 편종의 조율 상태가 양호하지 못한 점, 현대 국악에서 기준 황종음고를 서양의 C4로 정하는 경향 등을 그 차이의 원인으로 해석할 수 있다. 편종의 음색을 결정하는 고차 모드진동수의 기명진동수에 대한 상대적인 비율을 조사한 결과, (3,0)a와 (3,0)b모드를 제외한 모든 고차 모드진동수에서 유의미한 차이를 나타냈다. 이 차이는 통계적으로 유의미할 뿐만 아니라 최소가지진동수 이상이었다 이것은 유물 편종과 현대 편종 사이에 음색의 차이가 있음을 시사한다. 조율방안을 모색하기 위해서는 보다 많은 유물 편종에 대한 추가적인 음향 분석, 주물 분석 및 구조에 대한 연구가 필요하다.

• 대한수의학회지
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• 제39권6호
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• pp.1038-1048
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• 1999

The regional distributions and relative frequencies of the gastrointestinal endocrine cells in the bean goose (Anser fabalis Latham) were investigated by immunohistochemical methods using bovine Sp-1/chromogranin (CG), serotonin, gastrin, cholecystokinin (CCK)-8, somatostatin and glucagon antisera. BCG-immunoreactive cells were widespread throughout the gastrointestinal tract (GIT) with moderated frequencies except for the gizzard and proventriculus which were a few frequencies. Serotonin-immunoreactive cells were detected throughout the GIT except for the proventriculus and gizzard. These cells were observed in the pylorus with rare frequencies but numerous cells were detected in the intestinal tract. Gastrin-immunoreactive cells were restricted to the gizzard, pylorus and duodenum. These cells were most predominant in the pylorus and a few or rare in the gizzard and duodenum, respectively. CCK-8-immunoreactive cells were observed from the gizzard to ileum. The highest frequencies of endocrine cells were observed in the duodenum. These cells were increased from the gizzard to duodenum but thereafter decreased. Somatostatin-immunoreactive cells were detected in the GIT except for the large intestine. In the proventriculus and pylorus, numerous immunoreactive cells were demonstrated but a few cells were present in the other regions. Glucagon cells were observed in the gizzard, pylorus, ileum, colon and rectum with a few or moderated numbers.

• Structural Monitoring and Maintenance
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• 제6권2호
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• pp.85-101
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• 2019

The effects of foundation scour depth and riverbed condition on the natural frequencies of a typical cross-river integral abutment bridge have been studied. The conventional operational modal analysis technique has been employed in order to extract the modal properties of the bridge and the results have been used in the Finite Element (FE) model updating procedure. Two tests have been carried out in two different levels of water and wet condition of the riverbed. In the first test, the riverbed was in dry condition for two subsequent years and the level of water was 10 meter lower than the natural riverbed. In the second test, the river was opened to water flow from the upstream dam and the level of water was 2 meter higher than the natural riverbed. The results of these two tests have also been used in order to find to what extend the presence of water flow in the river and saturation of the surrounding soil affect the bridge natural frequencies. Finally, the updated FE model of the bridge has been applied in a series of parametric analyses incorporating the effect of piles' relative scour depth on the bridge natural frequency of the first four vibration modes.

• 전기의세계
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• 제28권2호
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• pp.68-75
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• 1979

The penetration of an electro-magnetic wave through an aperture in a cylindrical structure with a center dielectric-rod is investgated. By using a standard mode matching procedure, the electrical and magnetic fields in a cavity are determined as a function of position inside the cavity and frequency of the incident field. For the given parameters, computed data are obtained and the results exhibited in form of amplitude curves of the nor malized field and energy densities of functions of position and frequency. Depending on the increase of the relative dielectric constant of center dielectric-rod, the resonance frequecies of the cavity vary as the cavity size decrease. The stored electro-magnetic energy varies very rapidly as a function of position inside the cavity and of the source frequency. Its peak value can be two orders of magnitude greater than the incident energy density. The frequencies where the peaks occur can be identified approximately as the resonance frequencies of the cavity.

• 한국소음진동공학회논문집
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• 제13권10호
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• pp.805-812
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• 2003

This paper presents a method to investigate the characteristics of a ball bearing and the dynamics of a HDD spindle system due to temperature variation. Finite element model is developed for the rotating and stationary parts of a HDD spindle system separately to determine their thermal deformations by using ANSYS, a finite element program. Then, the relative position of the rotating part with respect to the stationary part is determined by solving the equilibrium equation of the contact force between upper and lower ball bearings. The validity of the proposed method is verified by comparing the theoretical natural frequencies of a HDD spindle system with the experimental ones before and after temperature variation. It shows that the elevated temperature results in the increase of contact angle and the decrease of bearing deformation, contact force and bearing stiffness, which result in the decrease of the natural frequencies of a HDD spindle system.