• 한국가스학회지
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• 제15권1호
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• pp.22-29
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• 2011

도심지 내 공사 현장 및 주변 지반에 매설된 지중 배관은 시공하중에 의한 진동에 노출이 되어있는 실정이다. 주기적으로 진동이 발생하는 매설된 배관의 지중 동적 거동 특성을 분석하기 위하여 기존 문헌 분석과 실증 실험의 결과를 토대로 수치해석을 수행하고 그 사용성을 검증하였다. 본 논문은 건설 장비중 하나인 덤프 트럭 하중의 매설 심도에 따른 배관의 거동을 분석하여 향후 지중 배관 관리기준 수립을 위한 기초 연구로서 수행되었다. 매설 심도 0.6, 1.2, 1.8m 차량 이동 속도 10km/h에 대하여 해석을 실시하였으며, 그 결과 매설 심도가 깊어질수록 진동속도 및 발생 응력이 작아지는 것을 확인할 수 있다.

• Membrane and Water Treatment
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• 제11권1호
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• pp.11-23
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• 2020

The effectiveness of in situ sediment capping as a technique for heavy metal risk mitigation in Hyeongsan River estuary, South Korea was studied. Sites in the estuary were found previously to show moderate to high levels of contamination of mercury, methylmercury and other heavy metals. A 400 m × 50 m section of the river was selected for a thin layer capping demonstration, where the total area was divided into 4 sections capped with different combinations of capping materials (zeolite, AC/zeolite, AC/sand, zeolite/sand). Pore water concentrations in the different sites were studied using diffusive gradient in thin film (DGT) probes. All capping amendments showed reduction in the pore water concentration of the different heavy metals with top 5 cm showing %reduction greater than 90% for some heavy metals. The relative maxima for the different metals were found to be translated to lower depths with addition of the caps. For two-layered cap with AC, order of placement should be considered since AC can easily be displaced due to its relatively low density. Investigation of methylmercury (MeHg) in the site showed that MeHg and %MeHg in pore water corresponds well with maxima for sulfide, Fe and Mn suggesting mercury methylation as probably coupled with sulfate, Fe and Mn reduction in sediments. Our results showed that thin-layer capping of active sorbents AC and zeolite, in combination with passive sand caps, are potential remediation strategy for sediments contaminated with heavy metals.

• Journal of Welding and Joining
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• 제31권5호
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• pp.47-53
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• 2013

We have investigated the traits of clad metals in hot-rolled clad steel plates, including the sensitization and mechanical properties of STS 316 steel plate and carbon steel (A516), under various specific circumstances regarding post heat treatment, multilayered welds, and thick or repeated welds for repair. For evaluations, sectioned weldments and external surfaces were investigated to reveal the degree of sensitization by micro vickers hardness, tensile, and etching tests the results were compared with those of EPR tests. The clad steel plates were butt-welded using FCAW and SAW with the time of heat treatment as the variable, a that was conducted at $625^{\circ}C$, for 80, 160, 320, 640, and 1280 min. Then, the change in corrosion resistance was evaluated in these specimens. With carbon steel (A516), as the heat treatment time increased, the annealing effect caused the tensile strength to decrease. The micro-hardness gradually increased and decreased after 640 min. The elongation and contraction of the area also increased gradually. The oxalic acid etch test and EPR test on STS316 and the clad metal showed STEP structure and no sensitization. From the test results on multi-layered and repair welds, it could be concluded that there is no effect on the corrosion resistance of clad metals. The purpose of this study was to suggest some considerations for developing on-site techniques to evaluate the sensitization of stainless steels.

• 한국해안·해양공학회논문집
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• 제24권4호
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• pp.247-256
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• 2012

본 연구는 다층지반으로 구성된 방조제의 침투변화에 따른 안정성을 검토하기 위하여 현장조사와 역해석 방법으로 투수계수와 침투수량을 결정하고, 제체의 변형량과 유실량 측정을 위하여 침투모형시험을 수행하여 가장 합리적인 수치해석 방법을 결정하였다. 검토결과 방조제는 다층지반구조물로 투수계수 차이에 의해 바닥보호공과 성토체 경계부에서 유실이 발생하고 이로 인해 방조제의 변형이 발생한다는 것을 예측할 수 있었다. 한편 침투모형 시험에 대한 수치해석결과 한계유속에 의한 방법은 실측치가 해석값보다 작게 나왔으나 그 경향이 유사하여 실제 단면에 적용 가능할 것으로 판단되었다.

• Applied Microscopy
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• 제22권2호
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• pp.66-74
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• 1992

In an attempt to produce transgenic amphibia, bacteriophage ${\lambda}-DNA$ was microinjected into fertilized eggs of Xenopus laevis, and the effect on early embryogenesis and the ultrastructural behavior of exogenous DNA were investigated. The effect of microinjected gene on embryonic development showed differences according to the concentration of injected DNA and the incubation temperature. Various concentrations of ${\lambda}-DNA$ were tested. Among those, microinjection of 1-2 ng DNA dissolved in 20 nl TE buffer was not shown to disturb normal embryonic development and was recorded the highest survivability to the late tadpole stage (Stage 43); however, injection of increased concentrations of DNA than above provoked irregular cleavages or abnormal appearances, which resulted in reduced survivability. When the injected embryos were incubated at low temperatures (e.g., $12^{\circ}C$), 54.5% of the embryos developed to Stage 43, whereas 42.4% survived when incubated at room temperature. The survivability showed also differences according to the injection site. 58.0% of the embryos developed to Stage 43 when microinjected into the vegetal pole, whereas 44.9% survived when microinjected into the animal pole. To understand the structural fate or behavior of injected DNA a combined light and electron microscopical study was applied. The nucleus-like structure was observed in the ${\lambda}$ DNA-injected embryos, which was quite a similar to the interphase nuclei of normal Xenopus laevis. The nucleus-like structure showed the typical double-layered nuclear membrane and nuclear complexes; however, it consisted of unusual structures such as furrows of nuclear envelope into the nucleoplasm.

• 한국지반공학회논문집
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• 제18권3호
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• pp.33-41
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• 2002

쏘일네일링 공법은 굴착이나 사면안정을 위해 가시설이나 영구용으로 국내에서 널리 이용되고 있다. 특히, 도심지 근접 굴착시 쏘일네일링 공법 적용시 고려사항은 벽체변위와 네일의 인장등 이다. 본 연구는 국내 여러 암반층을 포함하는 다층토 지반의 11개 쏘일네일링 현장에서 굴착단계별 네일의 인장력 거동을 계측자료와 역해석을 통하여 고찰하였다. 역해석 결과 네일의 최대인장력은 계측값의 50% 정도로 낮게 나타났고, 벽면에서 가상 파괴활동면까지의 거리를 주동영역거리라 할때 CLOUTERRE 보고서와 Cartier & Gigan이 각각 제안한 최종굴착 깊이(H$_{f}$ )의 0.3$H_f$,0.5$H_f$,에 비해 계측결과는 크게 나타났으며, 역해석은 이들이 제안한 범위내에 포함되었다.

• Journal of Periodontal and Implant Science
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• 제50권3호
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• pp.197-206
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• 2020

Purpose: The aim of this study was to determine the impact of different compressive forces on deproteinized bovine bone mineral (DBBM) particles covered by native bilayer collagen membrane (NBCM) during alveolar ridge preservation (ARP) in the molar area, and to identify any histomorphometric and clinical differences according to the compressive force applied. Methods: Sockets were filled with DBBM after tooth extraction, and different compressive forces (30 N and 5 N, respectively) were applied to the graft material in the test (30 N) and control (5 N) groups. The DBBM in both groups was covered with NBCM in a double-layered fashion. A crossed horizontal mattress suture (hidden X) was then made. A core biopsy was performed using a trephine bur without flap elevation at the implant placement site for histomorphometric evaluations after 4 months. The change of the marginal bone level was measured using radiography. Results: Twelve patients completed the study. The histomorphometric analysis demonstrated that the mean ratios of the areas of new bone, residual graft material, and soft tissue and the implant stability quotient did not differ significantly between the groups (P>0.05). However, the mean size of the residual graft material showed a significant intergroup difference (P<0.05). Conclusions: The application of 2 compressive forces (5 N, 30 N) on particulate DBBM grafts during open-healing ARP in the posterior area led to comparable new bone formation, implant feasibility and peri-implant bone level.

• 대한치과기공학회지
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• 제39권1호
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• pp.43-52
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• 2017

Purpose: Physical and chemical properties of gold is most suitable to be restored of teeth to its original state. Recently zirconia was used instead of gold because of esthetical and intimacy of human body. Because of high strength and high abrasion resistance of zirconia, all zirconia artificial tooth lead to wear the original tooth of opposite site. To preserve this original tooth, zirconia artificial tooth covered with dental ceramic glass was used. When joining the zirconia core and dental ceramic glass, difference of their thermal expansion coefficient and wetting ability is generated the residual stress at interface lead to crack. In order to solve this problem, intermediate layer what is called zir-liner was imported to decrease the residual stress and increase the bonding strength. Methods: In this study, to identify the optimum conditions for manufacturing process, various methods to rough the surface of zirconia core were adopted, and vary the thickness of interlayer, and analyzed bond strength. Results: Bond strength of sanding specimens group showed higher than that of non-sanding specimens group, and once applied intermediate layer with sanding specimens showed highest bond strength with 28 MPa. SEM photomicrographs of zirconia cores fired at $1500^{\circ}C$ showed parallel straight lines in sanding and pockmarked surface in blasting surfaces as abrasion traces. Observation of the destruction section after shear test by SEM were carried out. Liner applied non-sanding group and non-liner applied sanding group all showed interfacial crack. Sandblasting group with non-liner showed remained dental ceramic glass on the surface of zirconia. Sandblasting group with once applied liner showed partially remained liner and dental ceramic glass on the surface of zirconia. XRD analysis revealed that sandblasting group showed higher monoclinic peaks than other specimens group and this result was due to the high collision energy for stress induced phase transformation. Conclusions: A study on the improvement of bonding strength between zirconia and dental ceramic glass steadily carried out for the future to practical use.

• 한국조경학회지
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• 제42권2호
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• pp.10-18
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• 2014

본 연구는 최근 문화경관을 바라보는 새로운 도구인 장소기억과 형용사를 이용하여 경관의 숨겨진 구조와 특징을 해석하고자 하였다. 이를 위하여 반표준화 인터뷰를 사용하였으며 생애사적인 관점에서 인터뷰를 진행하였다. 연구는 산업화 시기를 거쳐 탈산업화 시기를 경험하고 있는 한국의 대표적 근대 산업도시 장항을 대상으로 하였다. 연구 결과, 우리가 바라보고 있는 경관은 정지하거나 고정된 것이 아닌 시간의 흐름 속에서 역동적으로 변화해 왔으며, 장항의 경우 산업화, 한국전쟁과 탈산업화에 의해 크게 구분되었고 그 속에는 수많은 기억의 층위들이 존재하고 있었다. 소수자와 개인의 집단기억은 사라지고, 지역의 산업발전을 상징하는 이미지만이 드러나고 있었다. 특히 일부 경관 이미지는 왜곡되어 있었다. 본 연구에서는 장소에 관한의 계보를 통해 그 위치와 이유를 밝혀낼 수 있었다. 본 연구는 기억을 통한 경관 읽기의 가능성을 살펴보았으며 형용사를 사용하여 구체화하였다. 더불어 우리가 바라보고 있는 경관이 우리가 일반적으로 생각하는 것과 같은 모습의 경관인지를 한번 의심해 볼 필요가 있음을 이야기하고자 하였으며, 경관의 생산자인 설계자와 계획가로서 또 다른 왜곡된 기억을 재생산하고 있는 것은 아닌지 함께 고민해 보고자 하였다.

• Journal of Rhinology
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• 제25권2호
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• pp.123-129
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• 2018

Background and Objectives: Endoscopic repair of cerebrospinal fluid (CSF) leak can avoid morbidity of open approaches and has shown a favorable success rate. Free mucosal graft is a good method, and multi-layered repair is more favorable. The inferior turbinate has been commonly utilized for the free mucosal graft, but we newly designed it as a bone-periosteal-mucosal composite graft for multilayered reconstruction. Subjects and Method: Four subjects with a skull base defect were treated with this method. The inferior turbinate was partially resected including the conchal bone and was trimmed according to defect size. Both bony parts and periosteum were preserved on the basolateral side of the mucosa as a composite graft. The graft was applied to the defect site using an overlay technique. Results: All cases were successfully repaired without any complications. Three of them had a defect size greater than 10-12 mm, and the graft stably repaired the CSF leakage. Conclusion: Endoscopic repair of CSF leakage using inferior turbinate composite graft is a simple and easy method and would be favorable for defect sizes greater than 10 mm.