• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.673-676
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• 2008

Recent trends show an increased usage of 'colored concrete', a inorganic pigmented concrete mix, especially in small to large scale buildings. However, due to lack of regulations, current usage of colored concrete indicates a lack of consideration for safety factors and aesthetic aspects. Sometimes color pigmentation used in paints are inappropriately used in concrete, and in many cases the addition of coloring material is done without proper research into how structural characteristics of resulting concrete may have been affected. To resolve these issues, some construction sites apply ASTM or ACI regulations. However, such regulations incorporate elements that cannot be applied in Korea, which makes their domestic application impractical. In this paper, the primary aim is to determine to what extent the basic material characteristics of concrete is affected by the variety and quantity of different color pigments, and in so doing establish a foundation for future reference in case of construction projects involving the use of colored concrete.

• Fire Science and Engineering
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• v.33 no.4
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• pp.140-151
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• 2019

It is to assess the indoor air quality of the chemical hazardous materials exposed to the fire after firefighters returned to the fire scene. The research subject randomly selected four fire stations located in Seoul, Korea. Two fire stations were set up as control groups after the return of the firefighting activities at the actual fire scene, and two other fire stations were set up as control groups to measure the air quality of the room at normal levels regardless of the action. We conducted 24-hour monitoring for all fire accidents that occurred in Seoul Metropolitan using fire safety map computer system. Also, indoor air quality was measured immediately after homecoming if the experiment group was to be dispatched due to an accident of intermediate or larger scale. 11 hazardous substance items such as fine dust, formaldehyde, volatile organic compounds, PAH, VCM, acidity, asbestos, CO₂, NO₂, O₃ were measured according to the process test method. Three of 11 types of harmful substances exceeded domestic and foreign standards, and one of them was found to be close to foreign standards. In particular, total volatile organic compounds, carbon dioxide and sulfuric acids were 2.5 times, 2.2 times and 1.1 times higher than the standard. Also, for formaldehyde and sulfuric acid, it was measured higher in the control group than in the case group. This findings could be used in policies to improve indoor air quality in the fire station of the Seoul Metropolitan Government.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.148-156
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• 2022

Although most domestic concrete structures are simultaneously exposed to freeze-thaw and chloride environments, concrete durability in the field is evaluated by each single action, and the evaluation of chloride-caused damage of concrete requires additional indoor experimental analysis of chloride contents by coring samples from structures in the field. However, in Korea, policies to strengthen facility maintenance, such as 「Special Act on the Safety Control and Maintenance of Establishments」 and 「Framework Act on Sustainable Infrastructure Management」, have been established and implemented since 2018 and facilities subject to safety inspection management by the government and local governments increases, the effective simplification technology for the inspection and diagnosis of concrete structure is needed. Therefore, this study attempted to evaluate the possibility of determining the acceleration chloride penetration of freeze-thaw damaged concrete by using the surface rebound value. For this purpose, concrete specimens already having freeze-thaw damage by exposure to the freeze-thaw acceleration environment were immersed in chloride water. After that, the acceleration relationship of chloride penetration according to freeze-thaw damage was analyzed using the amount of chloride contents in concrete.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.86-86
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• 2011

토목 기술의 발달로 장대교량이 증가함에 따라 교면 포장도 더 심각한 진동 및 충격, 기상조건에 노출되게 된다. 교면 포장은 차량의 주행의 편리성뿐 아니라 교량 구조물을 보호해야 하는 역할도 함께 수행하기 때문에 일반 토공부의 포장과 다른 성능을 필요로 한다. 교면 포장의 특수함을 감안하여 교면 포장의 품질을 평가하고, 설계와 적용시 반영 한다면 교량의 내구 연한 및 시공, 유지관리 비용을 절감 할 수 있을 것이다. 본 논문에서는 교면 포장에 요구되는 성능을 조사하고, 교면 포장 특히, 장대 교량 적용시 교면 포장의 성능 평가를 위한 평가 방법을 고찰하였다. 교면 포장의 가장 큰 구조적 특징은 교량의 진동과 휨에 의해 포장이 받게 되는 휨응력이다. 특히 교량의 장경간화에 따라 더 큰 진동과 변형을 경험하게 되는 교면 포장은 그에 따른 충분한 휨 추종성과 피로 저항성을 확보하여야 한다. 기존 토공부 포장에서는 실험이 간단한 원통형 공시체를 이용한 간접인장강도 모드의 실험으로 피로 성능을 평가하였으나, 교면 포장은 실제 거동 특성과 유사한 빔 피로 시험 모드가 보다 신뢰성이 높을 것으로 판단된다. 빔 피로시험 모드로는 3점, 4점, 5점 휨 피로 시험 모드가 있으며, 각각의 모드는 지지점의 개수, 재하점의 개수에 따라 다른 거동 특성을 평가 할 수 있다. 최근 개발된 5점 휨 시험의 경우 교량에서 발생하는 부(-)모멘트를 모사할 수 있어 보다 현실적인 검증이 가능할 것으로 예상된다. 이 외에도 실제 크기 모형을 이용하여 윤하중을 가하는 Full-scale 모델의 경우 비용과 시간이 많이 소요되는 단점이 있으나 가장 신뢰성이 높은 방법이라고 할 수 있다. 교면 포장은 교량구조부로 수분이 침투되는 것을 막아주는 역할을 하여야 하며, 특히 해상 교량의 경우의 염분과 겨울철 사용되는 제빙화학제는 콘크리트의 열화와 강구조물의 부식을 발생시키므로 교면 포장의 방수 성능 검토는 매우 중요한 역할을 한다. 일반 토공부 포장과 달리 교면 포장은 하부층이 대기에 노출되어 있기 때문에 겨울철에 더 낮은 온도로 포장체의 온도가 내려가게 되고, 온도가 떨어진 포장층은 스티프니스가 증감함에 따라 저온 균열의 발생확율이 높아지며, 휨추종성도 나빠질 가능성이 높다. 따라서 저온에서의 균열 저항성 및 스티프니스를 평가하는 것은 교면 포장 재료의 중요한 인자 중 하나이다. 포장과 포장 하부층의 접착은 포장층의 일체화된 거동을 할 수 있게 하기 때문에 내구성 향상에 중요하다. 특히 교량과 같이 진동과 변형이 많은 경우에 있어 포장 접착층의 성능은 포장과 교량 구조물의 파손에 더 큰 영향을 미치게 된다. 접착성능은 실내에서의 직접인장모드와 전단접착강도 시험 모드의 실험이 있으며, 현장에서 측정하는 Pull-off 실험 등이 있다. 최근에 교통량과 중차량의 증가와 더불어 교량이 장경간화 되어 가면서 평가방법과 기준을 과거보다 엄격하게 할 필요성이 있다. 하지만 현실은 교면포장에 대한 시방규정이 모호하기 때문에 본 논문에서 제시한 국내외의 다양한 평가방법을 통해 적절한 교면포장의 성능을 평가하고 교면포장의 거동특성에 대한 이해를 함으로써 보다 발전된 교량기술을 확보할 수 있을 것이다.

• Korean Journal of Heritage: History & Science
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• v.54 no.1
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• pp.206-219
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• 2021

The warming of the climate is increasing the damage caused by termites to wooden buildings, cultural properties and houses. A group removal system can be installed around the building to detect and remove termite damage; however, if the site is not visited regularly, every one to two months, you cannot observe whether termites have spread within, and it is difficult to take prompt effective action. In addition, since the system is installed and operated in an exposed state for a long period of time, it may be ineffective or damaged, resulting in a loss of function. Furthermore if the system is installed near a cultural site, it may affect the aesthetic environment of the site. In this study, we created a detection system that uses wood, cellulose, magnets, and magnetic sensors to determine whether termites have entered the area. The data was then transferred to a low power LoRa Network which displayed the results without the necessity of visiting the site. The wood was made in the shape of a pile, and holes were made from the top to the bottom to make it easier for termites to enter and produce a cellulose sample. The cellulose sample was made in a cylindrical shape with a magnet wrapped in cellulose and inserted into the top of a hole in the wood. Then, the upper part of the wood pile was covered with a stopper to prevent foreign matter from entering. It also served to block external factors such as light and rainfall, and to create an environment where termites could add cellulose samples. When the cellulose was added by the termites, a space was created around the magnet, causing the magnet to either fall or tilt. The magnetic sensor inside the stopper was fixed on the top of the cellulose sample and measured the change in the distance between the magnet and the sensor according to the movement of the magnet. In outdoor experiments, 11 cellulose samples were inserted into the wood detection system and the termite inflow was confirmed through the movement of the magnet without visiting the site within 5 to 17 days. When making further improvements to the function and operation of the system it in the future, it is possible to confirm that termites have invaded without visiting the site. Then it is also possible to reduce damage and fruiting due to product exposure, and which would improve the condition and appearance of cultural properties.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.553-558
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• 2012

Airborne chlorides are transported to inland by sea wind to be attached to seashore concrete structure surface then penetrated into concrete structure members. Since the surface attached chloride amount are dependent on the amount of airborne chlorides, the prediction of distribution of airborne chlorides is important information in preventing chloride corrosion problems in seashore concrete structures. The prediction of surface chloride amount from airborne chlorides environment is extremely difficult than concrete directly in contact with seawater. In addition, their penetrating tendency is different from that of concrete immersed in seawater. In this study, properties of surface and penetrated chlorides under airborne chlorides environment are investigated. Concrete specimens were manufactured and exposed to marine environment for 3 years. The specimens were analyzed at the time durations of 1, 2, and 3 years to check surface chloride amount to penetrated chloride depth. The results revealed that there were certain differences according to surface roughness of concrete and with and without washing effect due to rainfalls. The evaluation results showed that penetrated chlorides depend on amount of airborne chlorides and duration of exposure. In addition, a notable tendency of having deeper chloride penetration and higher chloride content in concrete members under long-term exposure was observed.

• Proceedings of the ESK Conference
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• 1996.10a
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• pp.56-56
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• 1996

인간의 사고 기능과 학습기능이 '뇌'를 바탕으로 이루어진다고 할 때, 뇌의 긴장을 풀어 원래의 건강하고 창조적인 이완 상태에서의 학습 상태가 유효하게 된다. 즉, 뇌파가 " $\alpha$" 상태 가 되었을 때 긴장된 신체의 각 부분이 충분히 이완되고 두뇌는 맑고 건강한 상태를 유지하여 활발하고 창조적인 상태가 된다. 뇌파의 측정 및 분석된 기존 연구에 의하면, 인간의 심리상태와 신체 상태, 행동 패턴에도 직, 간접적인 영향을 주어 뇌파의 조절이 인간 잠재능력 개발의 첩경이라는 결과가 보고되어진다. 이러한 관점에서 본 연구에서는 뇌의 특성을 고려하여 뇌를 이완시킴으로써 학생들의 학습능력을 향상시키 기 위한 새로운 접근 방법을 시도한다. 뇌파 조절이 가해지는 환경하에 학습 효율의 변화 정도를 정성적( 심리적, 학습적, 신체적) 및 정량적(영어 단어 암기력 TEST, 뇌파 특정 등)으로 평가 및 분석을 통해 뇌파 조절 효과가 학생들의 학습 효율을 더욱 향상 시킬 수 있는 지의 타당성을 검증하고 그 결과를 바탕으로 새로운 학습 방법을 모색하고자 한다. 한편, 본 연구에서는 실험 대상을 본 대학 임의의 2학년 학생 13 명 을 대상으로 하고 실험기간은 약 4개월에 걸쳐 실험 하였다. 뇌파 측정은 13명중 임의의 학생 7명을 선정 하여 각 40분씩 측정 분석하였다. 또한 영어 단어 암기력 TEST를 실시하여 그 결과를 뇌파 조절 전,후로 나누어 비교 분석하였다. 정성적 분석으로서 종합 설문지를 이용한 15 개 항목의 5점 척도를 사용하여 분석하였으며 가가 통계 이론을 이용하여 검증하였다. 뇌파 측정은 수행 전후 비교 결과 " .alpha. " 노출 비율이 수행 전보다 수행 후가 다소 높은 비유로 나타났으며, 특히 영어 단어 암기력은 평균적으로 크게 상승되는 것으로 나타났다. 정성적 분석 결과에서는 많은 심리적 변화 상태가 나타나고 있지만 전체적으로 마음의 안정감, 몸의 긴장 이완에 따른 건강 상태 유지, 수업 집중도 향상 등이 나타났다. 위와 같은 종합 적 분석 결과에 따라, 본 연구는 제조 현장의 생산성 향상 및 품질 향상과 연계하여 작업자의 작업 집중도 향상, 작업자의 육체적, 심리적 변화에 따른 생산성 및 품질 향상 변화 정도 등의 산업공학(인간공학) 제 분야의 여러 측면에서 연구 및 적용이 가능하리라 사료된다.

• Journal of Korean Society of Steel Construction
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• v.17 no.1 s.74
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• pp.93-102
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• 2005

Manufacturing conventional column base plate requires much manpower and time. In this research, a new method for constructing column base plate is introduced to improve on conventional methods through the use ofcast steel that is available for adjusting base plate thickness and enlarging base plate stiffness. The main purposes include reducing welding work, enlarging base plate stiffness, and clarifying the stress flow. Also, construction convenience and improvement in quality can be expected. For developing this cast steel base plate, test specimens of conventional and cast steel base plates are made and tested to analyze strength and stiffness. Also, the efficiency for long-term use is checked by fatigue tests. From these comparative tests, cast steel base plates have the same strength and stiffness as conventional base plates.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.4
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• pp.226-234
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• 2002

A sediment exposure experiment was conducted to investigate the influence of acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) in sediments on the bioavailability and toxicity of Cd, Ni and Zn to a marine polychaetes Neanthes arenaceodentata. The test animals were exposed to contaminated sediments spiked by metal mixtures of Cd, Ni, Zn (0.5～15 $\mu$mol/g of total SEM) in low (～1 $\mu$mol/g), medium (～5 $\mu$mol/g) and high AVS series (～10 $\mu$mol/g) to determine bioaccumulation, mortality and individual growth rate in each treatment after 20 days. Cd and Zn bioaccumulation in test animals increased with increasing of overlying water (OW) concentration controlled by AVS. In contrast, Ni bioaccumulation increased with increase of SEM concentration. Mortalities and growth inhibitions of N. arenaceodentata observed in only treatments with ［SEM-AVS］>0, due to a high level of OW-Zn. With regard to the mortality, the 20-d LC5O value fur OW-Zn was 9.3(8.0$\pm$11.0) $\mu$M. The LOEC (Lowest Observed Effect Concentration) for Tissue-Zn was 7.8 $\mu$mol/g and the NOEC (No Observed Effect Concentration) was 6.2 $\mu$mol/g. Regarding the inhibition of individual growth rate, the LOEC fer Tissue-Zn was 5.9 $\mu$mol/g, and NOEC was 5.1 $\mu$mol/g. In this study, the toxicity of dissolved metals, especially for Zn, was overemphasized due to the reduced distribution coefficients (K$\_$d/s) of metals in the experimental sediments.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.359-360
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• 2009

This Study is performed Mock-up test accounting for height of placement to review behavior of mass concrete according to kinds of cement & form. First, we measured hydration heat and show a different hydration heat generation characteristics as compared with each other. And we measured mortar outflow, the strength of concrete core and standard specimens, concrete's ability to resist chloride ion penetration in order to durability estimation of concrete. This study was aims to improve quality of mass concrete under marine environment.