• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.4
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• pp.314-321
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• 2000

A gap between a $Al_2O_3/Fe$ thermite and lower head vessel is formed in the lower-plenum arrested vessel attack(LAVA) experiment which is the 1st phase study of simulation of naturally arrested vessel attack in vessel(SONATA-IV). The gap measurement using a conventional ultrasonic method would be lack of a reliability due to the structure complexity and the metallurgical grain size change of the lower head HAZ occurred by a thermite $Al_2O_3/Fe$ melt or a $Al_2O_3$ melt at $2300^{\circ}C$. The grain echoes having false signals and lower S/N ratio signals are detected due to a multiple scattering, a mode conversion and an attenuation of a ultrasonic resulted from at the interface of increased grain size zone. In this test, the signals pattern was classified to understand the behavior of the ultrasonic in a multi-layer specimen of solid-liquid-solid of assuming that the thermite and the lower head vessel is immersed. The polarity threshold algorithm of frequency diversity gives us the enhancement about 6dB of the ratio S/N.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.3
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• pp.183-190
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• 2000

The purpose of this study is to evaluate the magnetic property change of the nuclear reactor vessel steel irradiated by fast neutrons using $M{\ddot{o}}ssbauer$ spectroscopy, and the effects of the defects produced by neutron irradiation on the changes using X-ray diffraction. The specimens, fabricated with the dimension of $23mm{\times}18mm{\times}70{\mu}m$, were irradiated by neutron fluence from $10^{12}n/cm^2\;to\;10^{18}n/cm^2$ at 343K. Throughout the experiments, it is understood that (1) the X-ray diffraction measurement shows that the change of crystal nature is started at the irradiation of $10^{16}n/cm^2$ and a crystal structure has been severely damaged at the irradiation over $10^{17}n/cm^2$, (2) the analysis of the $M{\ddot{o}}ssbauer$ spectra has shown that magnetic transition phenomena occur at the irradiation over $10^{17}n/cm^2$ and (3) both methods can be utilized as nondestructive test methods for the embrittlement evaluation of materials irradiated by fast neutrons.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.5
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• pp.436-441
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• 2009

A fiber optic sensor is prospective to be applied to structural health monitoring. Especially, a fiber Bragg grating(FBG) sensor is one of the most popular sensors for the structural health monitoring. The FBG sensor has several demodulation systems for tracking the shift of the Bragg wavelength. The dynamic bandwidth is dependent on the demodulation system. In this paper, the sensing mechanism is that the slope of the optical spectrum of FBG could be used as its sensitivity when the tunable laser shot the monochromatic laser wavelength at the highest slope point. In this technique, the high sensitivity is guaranteed even though the sensing range is limited. In an example of the application, the composite plate embedding a FBG sensor was manufactured by using an autoclave method and the above sensing mechanism was applied to the composite plate. Firstly, the natural frequencies of the plate were successfully measured by the FBG sensor during the impact hammer test. Secondly, a high-power speaker was used to force the plate to be vibrated at the specific frequency that was one of the natural frequencies. During the shaking, the FBG sensor measures the dynamic characteristics and ESPI was also used to measure the mode shape. From the two dynamic tests, the availability of the FBG sensor system and the ESPI was proven as a technique for measuring the dynamic characteristics of composite structure.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.1
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• pp.29-37
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• 2005

According to Confucianism, the world before Confucius focused on respecting the heaven which meant that everything could be done by the heaven. After the period of Confucianism, Joo-Ja asserted that everything could be done by nature. During the Chosun Dynasty, philosophers such as Seo Kyung-duck, Lee Hwang, and Lee Yi talked about four characters and seven passions of human being. They started to focus more on the inside of human nature. During the later period of the Chosun Dynasty, a philosopher by the name of Dongmugong Lee Jema analyzed that one's nature and feelings can change his or her external matter and the function of internal organs by purity or impurity of one's mind. Based on these analysis, Dongmugong discovered 'sasangin' which puts more emphasis on one's state of mind compared to the outside the world. Also, Dongmugong tried to figure out the connections between Confucianism and medical science. If you use change fire and stone theory which is difference between hado and nock-seo to expain four seven theory one's mind could be define as four natural characters and seven feelings. From four seven theory four is ying and seven is yang. This is the method of cure and understand the structure of human body. And also, four natural characters and seven feelings can be divided into heaven and earth. You can see Four natural characters is far more similar to heaven and seven feelings are similar to earth. According to four-seven theory hado is permanent and you can find out 'sasangin' is permanent also. Since seven feelings are influenced by sam-jae, you can analogize there are 21 different types in 'sasangin'. An underlying principle should there be 28 different types of sasangin instead of 21 different types of sasangin but one quater of sasangin is hidden according to samhyuniljang theory. All creations in the world are organized by unification of the great absolute and symmetry distinction of yingyang. With these facts identity of the heaven, earth and man which is named samjae generates symbols of independent sasang. And also, sasang generates relations between five element, six energy and the six family relation. From six family relation comes seven feelings of man which creates a category of the eight trigrams for divination and unification of nine palace. All these process are united.

• Childhood Kidney Diseases
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• v.3 no.2
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• pp.109-116
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• 1999

Purpose: Insulin-like growth factor(IGF)-I and -II are peptide growth factor whose activity is modulated by interaction with the family of six IGF-binding proteins(IGFBPs). IGF-I is detected in rat kidney and has metabolic and growth effects. This study was designed to examine temporal expression of IGFBPs in kidney during renal development and postischemic regeneration in rat. Method: The expression of IGFBPs in kidney during renal development from 15th day of gestation to adult life by using Northern blot analysis. We also examined the renal IGF-IGFBP axis in uremic rat by using Northern blot and immunohistochemistry. Results: The mRNA of IGFBP-1 and -3 were not or barely detected in fetal stages. However, the mRNA level of IGFBP-1 and -3 were increased gradually from day 7 after birth to adult. In contrast, the mRNA of IGFBP-2 and -5 were highly expressed in fetal stages and maintained almost same levels until day 7 (IGFBP-2) or day 30 (IGFBP-5) after birth, then their levels decreased markedly. The mRNA of IGFBP-4 were expressed moderately in fetal kidney and increased gradually after birth. Interestingly, the mRNA of IGFBP-1 and-4 were induced up to 3-5 fold during maximum regeneration period and were recovered to normal levels after acute ischemic injury. In contrast, the mRNA level of IGFBP-3 and-IGFBPrP-1 were decreased slightly at 1 day after ischemic injury, then recovered to normal level during maximum regeneration period. Conclusion: There were differential expressions of IGFBPs in kidney that can modulate IGF action on developing, differentiating, maintaining, and regenerating renal structure and function.

• International Commerce and Information Review
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• v.13 no.3
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• pp.377-401
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• 2011

Under the WTO system, direct export support system that provides financial and tax related support is altogether prohibited. This presented an obstacle in strengthening competitiveness of Korean export business and in increasing exports continuously. One of the methods used to solve this problem was to actively leverage export insurance. In Korea, export insurance services have been conducted by the Korea Trade Insurance Corporation (k-sure) to promote export. Korea has been among the world's active users of the export insurance system. Given this situation, this paper examines the effectiveness of the Korea export insurance system in the promotion of export. In particular, this study analyzed about discriminating effects of the export insurance on the export of big and small-medium business. In order to analyze, We introduce a Export Supply Function model. In this paper, We construct two model. The one is about big business, the other is small-medium business. For empirical analysis, unit-root test was conducted to understand the safety of time series. The results show that all variables are not I(0) time series. Instead, they are I(1) time series. To this, cointegration verification was conducted based on the use of Johansen verification method to define the existence (or non-existence) of long-term balance relationship among variables. The results come out as follows. The export insurance of big business has a stronger effect on export than that of small-medium business. The cause of these results is due to the distinct structure of Korea industries. In view of the fact that the insurance can make the risk decreased. We can say that the export insurance affects the export of a high-risk country.

• Journal of Korean Association for Spatial Structures
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• v.2 no.1 s.3
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• pp.85-92
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• 2002

Two way grid single-layer domes are of great advantage in fabrication and construction because of the simple fact that they have only four members at each junction. But, from a point of view of mechanics, the rectangular latticed pattern gives rise to a nonuniform rigidity-distribution in the circumferential direction. If the equivalent rigidity is considered in the axial direction of members, the in-plane equivalent shearing rigidity depends only on the in-plane bending rigidity of members and its value is very small in comparison to that of the in-plane equivalent stretching rigidity. It has a tendency to decrease buckling -strength of dome considerably by external force. But it is possible to increase buckling strength by the use of roofing covering materials connected to framework. In a case like this, shearing rigidity of roofing material increases buckling strength of the overall structure and can be designed economically from the viewpoint of practice. Therefore, the purpose of this paper, in Lamella dome and rectangular latticed dome that are a set of 2-way grid dome, is to clarify the effects of roofing covering materials for increasing of buckling strength of overall dome. Analysis method is based on FEM dealing with the geometrically nonlinear deflection problems. The conclusion were given as follows: 1. In case of Lamella domes which have nearly equal rigidity in the direction of circumference, the rigidity of roofing covering materials does not have a great influence on buckling-strength, but in rectangular latticed domes that has a clear periodicity of rigidity, the value of its buckling strength has a tendency to increase considerably with increasing rigidity of roofing covering materials 2. In case of rectangular latticed domes, as rise-span-ratio increases, models which is subjected to pressure -type-uniform loading than vertical-type-uniform loading are higher in the aspects of the increasing rate of buckling- strength according to the rate of shear reinforcement rigidity, but in case of Lamella dome, the condition of loading and rise-span-ratio do not have a great influence on the increasing rate of buckling strength according to the rate of shear reinforcement rigidity.

• Korean Journal of Environmental Agriculture
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• v.27 no.3
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• pp.231-238
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• 2008

This study proposed the method of phosphate recovery from municipal wastewater by using ferrous iron waste, generated from the mechanical process in the steel industry. In the analysis of XRD, ferrous iron waste was composed of $Fe_3O_4$ (magnetite), practically with $Fe^{2+}$ and $Fe^{3+}$. It had inverse spinel structure. In order to identify the adsorption characteristic of phosphate on ferrous iron waste, isotherm adsorption test was designed. Experimental results were well analyzed by Freundlich and Langmuir isotherm theories. Empirical constants of all isotherms applied increased with alkalinity in the samples, ranging from 1.2 to 235 $CaCO_3/L$. In the regeneration test, empirical constants of Langmuir isotherm, i.e., $q_{max}$ (maximum adsorption capacity) and b (energy of adsorption) decreased as the frequency of regeneration was increased. Experiment was further performed to evaluate the performance of the treatment scheme of chemical precipitation by ferrous iron waste followed by biological aerated filter (BAF). The overall removal efficiency in the system increased up to 80% and 90% for total phosphate (TP) and soluble phosphate (SP), respectively, and the corresponding effluent concentrations were detected below 2 mg/L and 1 mg/L for TP and SP, respectively. However, short-circuit problem was still unsolved operational consideration in this system. The practical concept applied in this study will give potential benefits in achieving environmentally sound wastewater treatment as well as environmentally compatible waste disposal in terms of closed substance cycle waste management.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.41-41
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• 2008

In general, polyimides (PIs) are used in alignment layers in liquid crystal displays (LCDs). The rubbing alignment technique has been widely used to align the LC molecules on the PI layer. Although this method is suitable for mass production of LCDs because of its simple process and high productivity, it has certain limitations. A rubbed PI surface includes debris left by the cloth, and the generation of electrostatic charges during the rubbing induces local defects, streaks, and a grating-like wavy surface due to nonuniform microgrooves that degrade the display resolution of computer displays and digital television. Additional washing and drying to remove the debris, and overwriting for multi-domain formation to improve the electro-optical characteristics such as the wide viewing angle, reduce the cost-effectiveness of the process. Therefore, an alternative to non-rubbing techniques without changing the LC alignment layer (i.e, PI) is proposed. The surface of LC alignment layers as a function of the ion beam (IE) energy was modified. Various pretilt angles were created on the IB-irradiated PI surfaces. After IB irradiation, the Ar ions did not change the morphology of the PI surface, indicating that the pretilt angle was not due to microgrooves. To verify the compositional behavior for the LC alignment, the chemical bonding states of the ill-irradiated PI surfaces were analyzed in detail by XPS. The chemical structure analysis showed that ability of LCs to align was due to the preferential orientation of the carbon network, which was caused by the breaking of C=O double bonds in the imide ring, parallel to the incident 18 direction. The potential of non-rubbing technology for fabricating display devices was further conformed by achieving the superior electro-optical characteristics, compared to rubbed PI.

• Journal of Korean Neurosurgical Society
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• v.30 no.1
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• pp.47-53
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• 2001

Objective : This study was undertaken to evaluate operative results and prognosis according to preoperative clinical status and histopathological finding of spinal cord tumor. Methods : We analyzed of clinical feature, tumor location, histopathologic finding, operative results and prognosis in 55 patients with spinal cord tumor during last 10 years. Results : 1) The incidence of spinal cord tumors varies with the age of affected patients who are 2 to 75 years of age. Peak incidences were in the 5th & 7th decade of life, and the ratio of male to female was 1.2:1. 2) The most common histopathologic type was neurinoma(41.9%). 3) The tumors were located most frequently in the thoracic area(22 cases, 40.0%) and in the intradural extramedullary space(30 cases, 54.5%). 4) The most common initial clinical feature was pain in 20 cases(36.4%). For neurologic status on admission, 30 cases(54.5%) showed motor disturbance. 5) In radiologic studies, there were abnormal finding in 21 cases from plain X-rays among 37 cases. The entire 20 cases in when myelography was done showed subarachnoid blockade, either complete or incomplete. The magnetic resonance imaging, regard as the most accurate diagnostic method, revealed the exact location of the tumor and the relationship of the tumor with the adjacent anatomical structure. 6) The total removal was possible in 36 cases(65.5%), subtotal removal in 17 cases(30.9%) and biopsy in 2 cases (3.6%). Nineteen cases(90.5%) among 21 cases with preoperative radiculopathy group showed recovery or improvement, where as only 11 cases(36.7%) among 30 cases with preoperative motor weakness group showed recovery or improvement, with statistically significant difference(p<0.01). Pathologically, 26 cases(83.9%) among 31 cases of neurinoma and meningioma showed postoperative recovery or improved, but only 1 case(6.3%) among 16 cases of metastatic tumor, astrocytoma and ependymoma recovered. Postoperative complication noted in 5 cases(9.1%), and were noted postoperative hematoma, pneumonia, pulmonary edema and spinal cord infarction. Conclusion : Preoperative neurologic status and histopathologic finding are considered important factors of Postoperative outcome in patients with spinal cord tumor.