• Journal of the Korean Institute of Oriental Medical Informatics
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• v.13 no.1
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• pp.14-25
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• 2007

기공시유구역사전통적문화(氣功是悠久歷史傳統的文化), 해탈생로병사고통적수련법(解脫生老病死苦痛的修練法), 거병건신(祛病健身), 심신단련(心身鍛鍊), 수명장수적양생법(壽命長壽的養生法). "기공"("氣功") 취시행기공부(就是行氣功夫), 이수련수행(以修練修行), 예방정신화육체질병(豫防精神和肉體疾病), 건강신체(健康身體), 연년익수(延年益壽), 기공적수련방법(氣功的修練方法), 유수형태(有數形態), 육체화정신적건강(肉體和精神的健康), 시의료기공(是醫療氣功), 의료기공시검토점(醫療氣功是檢討點), 통과고대의서적정리(通過古代醫書的定理). 의료기공시다개형태변화(醫療氣功是多個形態變化), 불교전파화일기(佛敎傳播和一起), 불가기공취재일개문파불가수련활동중형성(佛家氣功就在一個門派佛家修練活動中形成). 불가기공시(佛家氣功是), 수행자소추구적(修行者所追究的), 유지건강육체적기공법(維持健康肉體的氣功法). 의료기공적모습화구도적모습(醫療氣功的模襲和求道的模襲), 시혼합형태(是混合形態). 현재(現在) 불가기공지원류(佛家氣功之原流) 가이설시소림역근경(可以說是少林易筋經). 저본논고취시이의료기공적관점래접근소림역근경(這本論考就是以醫療氣功的觀點來接近少林易筋經).

• Journal of the Korean GEO-environmental Society
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• v.13 no.11
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• pp.61-68
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• 2012

Most widely methods for reinforcement of soil utilized in Korea are anchor method, soil nail method and micro pile method. These methods are classified by the intended use of the structure to be constructed, but the reinforcement of the ground is accomplished contains in common the process of grouting work after inserting the reinforcements. Domestically, gravity grouting has been used mostly so far, but there has always been the risk of insufficient restoration of the loose ground area from the drill holes because the grouting is conducted only by gravity. On the other hand, pressure reinjection grouting may enhance the grouting quality by solving the problem of the existing grouting method considerably since it additionally reinjects grouting through pre-installed tube a certain time after the first grouting. Accordingly, this study evaluated the pullout characteristics by the grouting methods by performing model test on decomposed granite soil, and investigated the support increasing characteristics of reinforcements depending on the curing time, reinjection pressure, and uplift force variation of the pressure reinjection grouting. The result of this research shows that the pressure reinjection grouting demonstrated 1.1~1.3 times of performance of the gravity grouting, and suggests some analysis on optimal water content, reinjection pressure and curing time of the pressure reinjection grouting.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.440-447
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• 2020

Masonry structures are used as bearing walls in small buildings, but they are generally considered non-bearing walls. They are used as partition walls that divide the interior spaces of the frame structures of buildings. In addition, wetting techniques that use mortar as an adhesive between blocks or bricks in construction are vulnerable to climatic conditions, especially cracks in mortar, which can cause conduction collapse of the walls in seismic loading. The purpose of this research was to propose a dry concrete block construction method that complements the weak axial shear stiffness and improves the weakness of the wet construction method as well as to investigate its structural behavior. In this study, the material properties of concrete blocks were examined, and the seismic performance of the proposed dry assembly structure was verified by structural behavior tests on horizontal cyclic loads. First, in these study results, concrete blocks can be applied to the dry block construction method instead of wet construction methods because they secure more than C-type blocks in KS regulations. Second, the structural performance of the wall against a horizontal cyclic load indicates that the resisting force of the assembly block wall is increased by increasing the horizontal length of the wall, forming several diagonal cracks. Finally, the proposed dry block wall structure requires a seismic performance assessment considering that the ratio of the shape of the wall by height and length is considered a major influence variable on the structural behavior under a horizontal load.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.20-27
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• 2014

In the construction site, various earth retaining systems are developed and applied to maintain stability of excavated area and structures. Among the methods, the underground continuous wall and the column-type diaphragm wall methods are especially used in construction site nearby buildings or roads. However, these methods have some disadvantages such as the difficulty of quality control and long curing time because these methods need to cast fresh concrete at the construction site. In addition, these methods are usually applied to the site for the temporary purpose. In this paper, we suggest precast hollow prestressed concrete pile for continuous pile wall system. To investigate the structural behavior of suggested pile, which is the main member of the suggested system, tests pertaining to the structural behavior and prestressing force applied in the pile are conducted. From the test results, it was found that the prestressing force measured is sufficient compared with the value obtained by the design equation and the cracking moment measured is 34% higher than the design value. In addition to the above, this precast hollow prestressed concrete pile has an additional safety margin that the maximum moment is 59.2% higher than the cracking moment which is one of the serviceability limits for the design of the system.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.480-480
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• 2018

전 세계적으로 자연 친화, 하천생태계 보전, 친수하천 등을 조성하기 위한 대대적인 하천 정비사업이 활발히 진행 중에 있다. 최근 홍수로 인한 제방 붕괴에 대응하기 위한 제방의 안정화 및 개선을 위한 방법으로 기존의 시멘트와 같은 혼합물질을 사용하지 않고 환경 친화적이고 지속 가능한 대안에 대한 수요가 증가되고 있는 추세이며 현재 노후화 된 불안정 제방에 대한 보강대책을 수립해나가는 과정으로써 친환경 신소재를 활용하여 제방을 보호하는 연구가 수행되고 있다. 제방사면에 적용되는 신소재는 바이오폴리머를 활용한 재료로써 공동연구기관 카이스트에서 개발된 환경 친화적인 물질로 미생물에 의해 유도된 고인장 및 인체 무해성 등의 특성을 갖고 있으며 경제적 타당성인 측면에서 시멘트와 비교 분석 되어야 하고 실제 현장에서의 적용 가능성, 신뢰성 및 내구성 검토 등 성능을 보장하기 위한 지속적인 연구가 필요한 상황이다. 이에 본 안동하천실험센터에서는 중규모 제방을 직접 제작하여 수리모형실험을 통한 친환경 신소재 활용 제방의 안정성 및 성능 평가를 실시하였다. 수리실험 조건은 카이스트에서 제시된 레시피를 기반으로 먼저 분말형태의 바이이폴리머를 물과 희석하여 만들어진 바이오폴리머 용액을 흙과 혼합한 뒤 제방표면에 직접 미장작업을 수행하여 실험조건에 따라 일정한 두께(1cm, 3cm, 5cm)로 피복하였다. 이후 월류 붕괴 실험이 가능한 3 - 5일 정도의 양생기간을 거쳐 실험을 진행하였다. 실험결과는 다수의 고프로(GoPro) 및 비디오 카메라 등 다양한 영상장치를 이용하여 픽셀기반의 영상분석기법을 활용한 시간 흐름에 따른 제방 사면에서의 붕괴규모를 산정하여 신소재의 피복 두께에 따른 제체의 붕괴 거동 및 안정성을 평가하였으며, 또한 제방 파괴부에서의 흐름 상황 및 유속이 붕괴 발달에 미치는 영향을 분석하기 위하여 PIV 분석을 실시하였다. 이번 연구의 최종목표는 지속적인 예비실험을 수행하여 월류 및 침투, 파이핑 등 파괴 인자 별 신소재의 성능 개선 및 개발된 새로운 공법에 대한 효과 검토를 통한 최적안을 도출함으로써 향후 실규모 실험실증을 통한 신소재 시공 및 공법에 대한 현장적용 가능성 검증을 거쳐 최종적으로 신소재 제방 공법 설계 기술, 신소재 및 공법 표준안, 제방공법 안정성 평가 가이드라인 등을 제시하고자 하며, 이러한 실험데이터를 축적함으로써 실제 제방 붕괴 시 비상대처계획 수립에 필요한 기초자료로 활용이 가능할 것으로 사료된다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.1-4
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• 2007

This study investigated the applicability of insulation curing method with double layer bubble sheets to the man concrete subjected to cold weather. Temperature history of the mass concrete indicated that the highest temperature of center section was exhibited at $34^{\circ}C$ while the that of surface section was $25^{\circ}C$. Difference between center and surface was shown to be less $10^{\circ}C$ when the temperature of center section was peak section, and thereby associated temperature cracking index was calculated 1.5, and occurrence probability of temperature cracking was 5%, so there was no temperature cracking caused by internal restraint. No temperature crack was observed by naked eye. It was clear that early frost demage and temperature cracking could be restrained due to reducing temperature difference between inner part and outside in the case double bubble sheets applied to insulation curing method in cold weather. The maturity of mass concrete is higher than outside about $72\sim89^{\circ}$ DD, so it was demonstrated to prevent early frost demage and ensure strength excellently. Insulation curing method with double bubble sheets was more economic than heating curing method.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.95-103
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• 2012

Precast concrete method is known to have advantages of minimizing works in the construction, controlling concrete quality easily and saving construction period due to only fabrication work in the construction field, but it needs to apply steam curing to accelerate early concrete strength. In the meanwhile, the oil cost for steam curing has been continuously increased because of political instability in the middle East and international economic shaky. Thus, this study addresses the development of precast/ prestressed concrete which has over 14MPa at 1 day age and specified concrete strength of 40MPa at low temperature, not applying steam curing. Tests were carried out in terms of material characteristics in fresh concrete and compressive strength using 3 types of cement such as Type I, Type III and rapid hardening compound cement. As results of tests, it is found that cements for rapid hardening had disadvantages with respect to slump, slump loss, and air content, but showed higher compressive strength than specified one, especially the highest value when using rapid hardening compound.

• Journal of the Korea Institute of Building Construction
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• v.10 no.5
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• pp.121-128
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• 2010

The present research examined heat insulation performance according to change of various laid construction conditions of double bubble sheet being used as material for heat insulation & curing construction of cold weather concrete, and its results are as follows. First, the change in a laid period of bubble sheet within 4 hours and the change in water content inside bubble sheet overall showed similar temperature history and maturity without a big difference in terms of the temperature history of concrete according to construction factors, but it could be confirmed that when a structure was thin or several bubble sheets are laid, requisites unfavorable for initial curing of concrete can occur if a lagger distance between sheets is generated. In terms of the compressive strength of concrete core specimens, it appeared that the initial compressive strength is declined when conditions unfavorable for concrete curing such as delay of a laid period of bubble sheets, induction of large distance between sheets, increase of water content inside bubble sheets and thinness of a structure of placing concrete, etc. were applied, but it appeared that as its age passes, the difference becomes small.

• Journal of the Korean GEO-environmental Society
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• v.17 no.10
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• pp.73-81
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• 2016

In the construction on low strength and high compressible soft ground, the many problems have been occurred in recent construction project. therefore, the soil improvement have been developed to obtain high strength in relatively short period of curing time. Based on the laboratory tests using undisturbed marine clay, the effect of improvement on soft ground was estimated. Deep mixing method by cement have been virtually used for decades to improve the mechanical properties of soft ground. However, previous researches set the focus on the short term strength the about 10% of cement treated clay. In this paper, cement and Natural Soil Stabilizer (NSS) were used as the stabilizing agent to obtain trafficability and mechanical strength of the soft clay. Based on the several laboratory tests, optimum condition was proposed to ensure the mechanical strength and compressibility as the foundation soil using cement and NSS mixed soil. Finally, research data was proposed about the applicability of NSS as the stabilizing agent to soft clay to increase the mechanical strength of soil.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.6
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• pp.811-823
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• 2019

Slip form method is applied to many cases of a shaft these days because it is safer, more economical and faster than cast-in-place method. Slip-up height of the method is approximately 2.5 to 4.0 m/day. If the temperature of concrete is outside the range of 10 to 30℃, the effects of changes in strength or elastic characteristics are significant. Therefore, it is difficult for slip-up speed to be higher than 3 m/day during winter construction. In addition, concrete has heat caused by hydration, which causes temperature cracking of hardened concrete. Therefore, temperature control of concrete curing is necessary for the continuous slip-up of slip form. In this study, the rebound hardness, time of ultrasonic waves propagation, heat of hydration, and external temperature are measured by developing heating panels and test devices for the continuous slip-up. Based on this, heating slip form is manufactured; this was applied to "Kimpo sites" and "Sinwol sites". The compared slip-up speed samples were 1.9 m/day or 0.200 m/hr on average at Gimpo sites (08:00~17:30) and 2.0 m/day or 0.210 m/hr at Sinwol sites.