최근 연달아 경주와 포항에서 발생한 지진 이후 국내에서는 지진파와 구조물 내진성능에 대한 사항을 새로운 문제로 인식하고 있다. 향후 매우 큰 지진이 발생할 가능성이 높아 내진보강 성능이 미흡한 석탄 화력발전소에 대한 내진 신뢰성 향상이 요구되고 있다. 본 연구에서는 화력발전소 보일러 구조물의 지진 시 거동을 파악하고자 축소모형을 통한 진동대 실험을 수행하였으며, 실험결과 보일러는 Pendulum 거동을 나타내어 구조물과 다른 주기거동을 보이는 것으로 나타났다.

본 연구는 구조물의 내진보강을 위하여 사용되는 제진장치의 일종인 마찰댐퍼의 개발에 관한 것으로 기존의 마찰댐퍼의 마찰재로 적용되고 있는 고무, 금속 등의 재료를 초고분자 복합재로로 대체하여 작은 진동 및 큰 진동에도 대응할 수 있는 속도의존형 마찰댐퍼를 개발하였다. 이를 실험적으로 검증하기 위하여 5, 25, 50, 100, 150mm/sec의 속도변화에 따른 마찰댐퍼의 마찰력과 마찰계수의 변화를 관찰하였다. 실험결과 속도변화에 따라 마찰댐퍼의 성능과 마찰계수가 변화하는 것을 확인할 수 있었다.

최근 프리캐스트 PSC 거더 형식의 교량이 널리 시공되고 있으며, 거더의 경간과 운송제한을 극복하기 위하여 분절거더의 시공이 증가하고 있다. 분절 공법을 적용한 세그먼트 간의 접합면에는 불연속면이 존재할 수 있으므로 교량의 건전성에 있어 접합부의 일체거동이 매우 중요하다. 분절 접합부는 접합부의 형태, 전단키 유무, 구속력의 크기에 따라 거동차이를 보이기 때문에 이러한 영향인자를 변수로 한 접합부 거동 연구가 필요하다. 본 연구에서는 프리캐스트 PSC 거더교의 접합부 거동을 평가하기 위하여 전단키의 형상, 구속력 도입여부를 변수로 한 전단키 유한요소해석과 축소모형시험을 실시하고, 그 결과를 비교하여 전단키와 구속력 효과를 평가하였으며, 접합부에 1/2~1/3의 돌출높이비를 갖는 전단키를 설치하고 콘크리트 강도의 1/2 수준의 구속력을 도입하는 것이 분절 접합부 거동향상에 효과적이라는 것을 확인하였다. 또한, 분절 공법으로 시공된 실제 프리캐스트 PSC 거더 교량의 재하시험을 실시하고 접합부 세그먼트 간의 처짐차이를 측정하여 분절부 거동을 평가하는 방법을 제안하였다.

In this research, the measurement of vibration for stay-cable installed in cable stayed bridge was carried out by using wireless accelerometer. The vibration measurement data can be used for the evaluation of safety and serviceability of cable stayed bridge. The acquired data was analyzed for the evaluation of maximum vibration, tension force and fatigue. To verify the reliability of data, the additional measurements with total station and video camera. The data from three different measurement methods showed similarity within 15 % gap.

In the cable wall system, the cable tension force can be changed by the various reasons. After 10 years from the construction of cable wall system in Hamad Medical City Womens Hospital of Qatar, an average of about 16% of the tension force was decreased. Since the tension loss can affect the structural capacity and stability, the re-tightening was carried out up to about 90% of the design tension. Also, the annual regular inspection including the measurement of cable tension is proposed as the maintenance plan.

The statistical data from WIM has been used only for traffic management and fatigue evaluation of structures. In this study, the algorithm using ESAL for assessment of pavement condition is proposed. To verify the algorithm, WIM system using PVDF sensor was installed on the pavement of bridge deck, also the automatic assessment software was developed. For the reliability verification of the alogorithm, further comparative study based on the long-term data is needed.

Thermal power generation was a very important power source in Korea. Therefore improvement of seismic reliability of the thermal power plants is required, because occurrence of very large earthquakes is expected in Korea. Especially, after the earthquake in Gyeong-ju and Po-hang, seismic waves are recognized as a new problem in Korea. In this study, numerical analysis was carried out in order to investigate behavior of the boiler structure in the thermal power plant under earthquakes. The effect of the developed hybrid damper is analytically confirmed.

Coal-fired thermal power generation was a very important power source in Korea. Therefore improvement of seismic reliability of the coal-fired thermal power plants is required, because occurrence of very large earthquakes is expected in Korea. Boilers of coal-fired power plants are usually suspended from the upper end of support structures in order to allow thermal expansion of the boilers, so boilers easily sway during earthquakes. In order to suppress the vibration, stoppers made of steel are generally installed between boilers and their support structures. Although stoppers made of steel are effective for vibration suppression, further countermeasure for earthquakes having long duration and many after shocks is required. This study has developed a hybrid damper for vibration and seismic control of coal-fired power plant boiler. The hybrid damper consists of an oil damper and a friction damper connected in series.

Recently many investigations have been conducted to evaluate and analyze the seismic response of structures equipped different types of damper. Viscous dampers are known as effective energy dissipation devices improving structural response to earthquakes. The damping force developed by the viscous damper depends on internal structural system and the physical properties of the fluid used in the device. This study has developed a viscous damper for vibration and seismic control of structures. In order to verify the performance of a viscous damper, experimental tests were performed.

Friction dampers are categorized as displacement-dependent energy dissipation devices, because their damper force is independent from frequency and velocity. They have found large practical application in seismic retrofitting of existing structures due to their low cost and simple installation. A typical friction damper consists of series of steel plates tighten together with high durability steel bolts in order to achieve more reliable friction through the interfaces. This study developed a multi-friction damper by laminating friction materials. In order to verify the performance of the multi-friction dampers, experimental tests were performed.

In thermal power plant, steam is made by boiler. As it rotates turbine, electric power is generated. Thermal power plant has a high-rise structure that has a boiler and other equipment. Thermal expansion of the boiler is large because combustion temperature is high. The boiler vibrates easily because it is suspended from the top of the support structure in order not to restrict deformation by thermal expansion. Thus, the boiler structure supported by the hanger is very vulnerable to earthquakes. In this study, numerical analysis was carried out in order to investigate behavior of the boiler structure in the thermal power plant under earthquakes.

In this study, the damping ratio was estimated using the developed automatic calculation software based on the field measurement data of vibration of stay cable in cable-stayed bridge. For the field measurement, two accelerometers were used for obtaining of dynamic behavior of 1st, 2nd and 3rd mode. The damping ratio after installation of the damper was calculated as higher than the requirement values, also it was confirmed that the damping effect was improved with the range of 19~92%.

In this study, prototype DAU with LoRa wireless communication module is designed and manufactured. Also, the customized software is developed for the automatic data transmission to end-user from ThingPlug server of SK telecom LoRa network. For verification of the developed wireless monitoring system, DAU was installed on bridge construction site. The reliability of data and operational stability was evaluated by comparison with data from conventional monitoring system.

Limonium tetragonum is a halophyte grown naturally in the coastal region in South Korea. This study was conducted to investigate the effects of salt concentrations on seed germination, seedling growth, and antioxidant capacity of L. tetragonum. Seeds were collected from naturally grown plants of L. tetragonum and those at full maturity were used in this experiment. All experiments were performed at 0%, 0.5%, 1.0%, or 2.0% of salt concentrations. Seed germination rate was highest as 86% at 20℃ and followed as higher in order of 25℃, 30℃ and 15℃. The germination rate was about 80% at 0% or 0.5% of salt concentration, but it was very low at the salt concentrations higher than 1%. Growth of L. tetragonum seedlings showed no difference in Hoagland solution containing NaCl in the range of 0% to 1.0% and seedlings survived at 2.0% of NaCl concentration. As the salt concentration increased, the content of Na+ in the shoot increased, but that of K+, Ca++, or Mg++ decreased. The antioxidant activity and the content of total polyphenol and total flavonoid in the shoot were similar at 0% and 0.5% of NaCl and were highest at 2.0% of NaCl concentration. In conclusion, performance of seed germination and plant growth of L. tetragonum was highest at 0% and 0.5% of NaCl concentration, and showed no difference in antioxidant activity, total polyphenol contents, and total flavonoid contents at the same salt concentrations.

This research was carried out to investigate the germination and seedling growth characteristics of the halophyte Suaeda asparagoides under various salt concentrations, temperatures, and the presence or absence of light S. asparagoides has a non-endospermic dicotyledonous seed structure that is go stone-shaped with a dark brown color and covered by a star-shaped perianth. Germination within the temperature range 5~40°C varied from 8% to 65%. The highest germination occurred at 15°C. In seeds exposed to salt concentrations in the range 0~400 mM, the highest germination occurred at 0 mM, and the germination progressively decreased as the salt concentration increased. When the perianth of the seed was removed, the germination increased significantly. In the presence or absence of light, germination under white light was 5~20% higher than that under darkness, which varied according to salt concentrations in the range 0~300 mM. The plant growth of S. asparagoides, evaluated by plant height, branch number, root length, fresh weight, and dry weight, was higher in the concentration range 50~100 mM, and it decreased in the other concentrations. In conclusion, the seeds of S. asparagoides showed higher germination in fresh water at low temperature of approximately 15°C under light when the perianth was removed, and the plant growth was higher at salt concentrations of 50~100 mM.

스테로이드 호르몬인 glucocorticoid (GC)는 glucocorticoid receptor (GR)와 결합하여 염증 유전자 의 발현을 억제함으로써 강력한 항염 효과를 준다. 따라서 GR을 활성화하는 GC 제제들이 개발되어 피부염의 치료제로 사용되어 왔다. 그러나 이러한 GC 제제들은 피부 장벽 기능 저하, 진피층 두께 감소 등의 부작용을 유발하여 피부를 손상시키고 피부 노화를 유발한다. 특히 GC 성분은 11 beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1)에 의해 활성화되어 GR의 활성을 높이는 것으로 보고되어 있다. 이에 본 연구에서는 스테로이드 제제인 dexamethasone에 의해 증가된 11β-HSD1의 발현을 효과적으로 억제할 수 있는 천연 소재를 발굴하고자 하여, 초두구 추출물에서 유래한 alpinetin에서 유의한 효과가 있음을 확인하였 다. Alpinetin은 진피 섬유아세포에서 dexamethasone에 의해 발현이 증가한 11β-HSD1를 억제함과 동시에 GR의 활성 및 cortisol의 생성을 감소시켰다. 또한 사람 섬유아세포 및 3D skin model을 이용한 평가에서, alpinetin은 dexamethasone에 의한 콜라겐 감소와 진피층 두께 감소를 효과적으로 회복시켰다. 따라서, 본 연구 결과로부터 alpinetin은 11β-HSD1의 발현 증가에 의한 피부 스트레스 및 피부 노화를 효과적으로 예방 할 수 있을 것으로 사료되었다.

Steel is a common structural material that is used for bridges, buildings, railroad tracks, wind towers, offshore platforms, and many other applications. Steel naturally corrodes in different atmospheric environments, which results in costs for corrosion protection, prevention and maintenance. The corrosion on steel elements is identified by optical examination, which does not provide information on the material characteristics. Studies have shown that Raman spectroscopy can identify the corrosion products of steel and differentiate between iron oxides and hydroxides. The purpose of this experiment is to validate the use of Raman spectroscopy in accurately identifying corrosion material on steel without a protective coating.

Structural performance of cable-bridge has been evaluated based on the field load test and the measurement monitoring system of existing Nielsen arch bridge. The measured acceleration data was converted to the displacement of girder and the tension of cable in the process of numerical integration and maximum frequency detection algorithm..

마이셀을 이용한 가용화 제형은 화장품 산업에서 스킨 로션, 토너, 미스트 등 다양한 제형으로 이용되고 있다. 마이셀은 입자 자체가 매우 작기 때문에 효능 물질의 담지체 역할보다는 향을 가용화시키는 정도로 활용 되고 있다. 본 연구에서는 효능 물질인 β-sitosterol을 담지 할 수 있는 새로운 마이셀을 개발하기 위하여 투 명한 외관을 갖는 swollen micelle을 고려하였다. 특히, 효능 성분과의 용해도 계수를 고려하여 swollen micelle을 제조함으로써 난용성 효능 성분이 마이셀 내부에 안정하게 존재할 수 있는 새로운 방법을 개발하였다. 이렇게 만들어진 swollen micelle의 안정도는 동적광산란장치(dynamic light scattering, DLS)를 이용하여 확인하였고, 투명한 입자의 외관과 모양은 육안 관찰 및 cryo-TEM을 통해 확인하였다. 또한, DSC를 이용한 열분석을 통해 난용성 효능 성분인 β-sitosterol이 swollen micelle 내에서 안정하게 존재함을 확인하였다. 본 연구를 통해 용해도 계수를 고려한 swollen micelle은 난용성 효능 성분의 새로운 담지체로서 이용할 수 있 음을 확인하였다.

대다수의 흙막이 공사 계측현장에서 적용하고 있는 절대치 관리방법은 관리기준치와 계측결과를 절대 비교함으로서 공사현장의 안전성을 평가하는 기법이다. 따라서, 안전성 평가의 판단기준이 되는 관리기준치는 평가결과에 직접적으로 영향을 미치게 된다. 즉 아무리 최 적의 계측시스템이 적용된 현장이라고 하더라도 관리기준치가 타당하지 않으면, 공사현장의 안전성을 정확히 판단할 수 없으므로 관리기준치 의 선정은 매우 중요하다. 그러나 실질적으로 현장 기술자 등은 기존 절대치관리기준치에 대한 신뢰성이 매우 낮으며 관리기준치의 수정보완 의 필요성을 인식하고 있다. 이에 본 연구에서는 계측관리기준치의 수정보완 필요성에 대한 조사결과를 바탕으로 하여 흙막이 구조물의 거동 중 가장 기본이 되며 중요한 흙막이 벽체의 변위에 대한 계측결과를 토대로 확률론적 이론에 의해 관리기준치를 보다 적절하게 설정하여 적용 하는 연구를 수행하였다. 본 연구에서는 계측관리기법 중 시공 전에 설정된 관리기준치와 시공 시 측정된 설측치를 비교 검토하여 그 시점에서 공사의 안전성을 확인하는 방법인 절대치관리방법을 적용하여 관리기준치를 수정하였다.