• 한국해양공학회지
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• 제15권3호
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• pp.29-29
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• 2001

The experimental studies for the artificial reef (AFR) subsidence characteristics in the unsteady flow field and in the unsteady flow-wave field were carried out. The difference of scour/subsidence characteristics between in the steady flow field and in the unsteady flow field wad discussed and also the long-term subsidence characteristics in the unsteady flow field were investigated. AFR subsidence characteristics was discussed with Keulegan - Carpenter number(KC), Reynolds number (Re),. Shields number (Sn) and dimensionless time (t/Tt). And the difference of subsidence characteristics between in the unsteady flow and in the unsteady flow-wave field was discussed.

• 한국해양공학회지
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• 제15권3호
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• pp.28-34
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• 2001

The experimental studies for the artificial reef (AFR) subsidence characteristics in the unsteady flow field and in the unsteady flow-wave field were carried out. The difference of scou $r_sidence characteristics between in the steady flow field and in the unsteady flow field wad discussed and also the long-term subsidence characteristics in the unsteady flow field were investigated. AFR subsidence characteristics was discussed with Keulegan - Carpenter number(KC), Reynolds number (Re),. Shields number (Sn) and dimensionless time (t/Tt). And the difference of subsidence characteristics between in the unsteady flow and in the unsteady flow-wave field was discussed.ed.

• Journal of Korean Neurosurgical Society
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• 제59권4호
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• pp.385-391
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• 2016

Objective : The purpose of this study was to evaluate long-term follow-up radiologic/clinical outcomes of patients who underwent anterior cervical discectomy and inter-body fusion (ACDF) with stand-alone cages (SAC) in a single academic institution. Methods : Total 99 patients who underwent ACDF with SAC between February 2004 and December 2012 were evaluated retrospectively. A total of 131 segments were enrolled in this study. Basic demographic information, radiographic [segmental subsidence rate, fusion rate, C2-7 global angle, and segmental angle changes)/clinical outcomes (by Odom's criteria and visual analog score (VAS)] and complications were evaluated to determine the long-term outcomes. Results : The majority were males (55 vs. 44) with average age of 53.2. Mean follow-up period was 62.9 months. The segmental subsidence rate was 53.4% and fusion rate was 73.3%. In the subsidence group, anterior intervertebral height (AIH) had more tendency of subsiding than middle or posterior intervertebral height (p=0.01). The segmental angle led kyphotic change related to the subsidence of the AIH. Adjacent segmental disease was occurred in 18 (18.2%) patients. Total 6 (6%) reoperations were performed at the index level. There was no statistical significance between clinical and radiological outcomes. But, overall long-term clinical outcome by Odom's criteria was unsatisfactory (64.64%). The neck and arm VAS score were increased by over time. Conclusion : Long-term outcomes of ACDF with SAC group were acceptable but not satisfactory. For optimal decision making, more additional comparative long-term outcome data is needed between ACDF with SAC and ACDF with plating.

• Journal of Korean Neurosurgical Society
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• 제52권2호
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• pp.107-113
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• 2012

Objective : Various procedures have been introduced for anterior interbody fusion in degenerative cervical disc disease including plate systems with autologous iliac bone, carbon cages, and cylindrical cages. However, except for plate systems, the long-term results of other methods have not been established. In the present study, we evaluated radiologic findings for cylindrical cervical cages over long-term follow up periods. Methods : During 4 year period, radiologic findings of 138 patients who underwent anterior cervical fusion with cylindrical cage were evaluated at 6, 12, 24, and 36 postoperative months using plain radiographs. We investigated subsidence, osteophyte formation (anterior and posterior margin), cage direction change, kyphotic angle, and bone fusion on each radiograph. Results : Among the 138 patients, a minimum of 36 month follow-up was achieved in 99 patients (mean follow-up : 38.61 months) with 115 levels. Mean disc height was 7.32 mm for preoperative evaluations, 9.00 for immediate postoperative evaluations, and 4.87 more than 36 months after surgery. Osteophytes were observed in 107 levels (93%) of the anterior portion and 48 levels (41%) of the posterior margin. The mean kyphotic angle was $9.87^{\circ}$ in 35 levels showing cage directional change. There were several significant findings : 1) related subsidence [T-score (p=0.039) and anterior osteophyte (p=0.009)], 2) accompanying posterior osteophyte and outcome (p=0.05). Conclusion : Cage subsidence and osteophyte formation were radiologically observed in most cases. Low T-scores may have led to subsidence and kyphosis during bone fusion although severe neurologic aggravation was not found, and therefore cylindrical cages should be used in selected cases.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권10호
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• pp.3554-3570
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• 2021

With the rapid development of the Chinese water project, the safety monitoring of dams is urgently needed. Many drawbacks exist in dams, such as high monitoring costs, a limited equipment service life, long-term monitoring difficulties. MEMS sensors have the advantages of low cost, high precision, easy installation, and simplicity, so they have broad application prospects in engineering measurements. This paper designs intelligent monitoring based on the collaborative measurement of dual MEMS sensors. The system first determines the endpoint coordinates of the sensor array by the coordinate transformation relationship in the monitoring system and then obtains the dam settlement according to the endpoint coordinates. Next, this paper proposes a dual-MEMS sensor collaborative measurement algorithm that builds a mathematical model of the dual-sensor measurement. The monitoring system realizes mutual compensation between sensor measurement data by calculating the motion constraint matrix between the two sensors. Compared with the single-sensor measurement, the dual-sensor measurement algorithm is more accurate and can improve the reliability of long-term monitoring data. Finally, the experimental results show that the dam subsidence monitoring system proposed in this paper fully meets the engineering monitoring accuracy needs, and the dual-sensor collaborative measurement system is more stable than the single-sensor monitoring system.

• Journal of Korean Neurosurgical Society
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• 제44권6호
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• pp.370-374
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• 2008

Objective : Aim of study was to find a proper method for assessing subsidence using a radiologic measurement following anterior cervical discectomy and fusion (ACDF) with stand-alone polyetheretherketone (PEEK), $Solis^{TM}$ cage. Methods : Forty-two patients who underwent ACDF with $Solis^{TM}$ cage were selected. With a minimum follow-up of 6 months, the retrospective investigation was conducted for 37 levels in 32 patients. Mean follow-up period was 18.9 months. Total intervertebral height (TIH) of two fused vertebral bodies was measured on digital radiographs with built-in software. Degree of subsidence (${\Delta}TIH$) was reflected by the difference between the immediate postoperative and follow-up TIH. Change of postoperative disc space height (CT-MR ${\Delta}TIH$) was reflected by the difference between TIH of the preoperative mid-sagittal 2D CT and that of the preoperative mid-sagittal T1-weighted MRI. Results : Compared to preoperative findings, postoperative disc height was increased in all cases and subsidence was observed only in 3 cases. For comparison of subsidence and non-subsidence group, TIH and CT-MR ${\Delta}TIH$ of each group were analyzed. There was no statistically significant difference in TIH and CT-MR ${\Delta}TIH$ between each group at 4 and 8 weeks, but a difference was observed at the last follow-up TIH (p=0.0497). Conclusion : ACDF with $Solis^{TM}$ cage was associated with relatively good radiologic long-term results. Fusion was achieved in 94.5% and subsidence occurred in 8.1% by the radiologic assessment. Statistical analysis reveals that the subsidence seen later than 8 weeks after surgery and the development of subsidence does not correlate statistically with the change of the postoperative disc space height.

• 문화기술의 융합
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• 제6권3호
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• pp.393-399
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• 2020

본 연구에서는 터널 굴진 시 조우한 석회공동의 지하수 유출에 따른 지반침하 거동을 수치해석을 바탕으로 정량화하고 영향정도를 분석하였다. 현장에서 조사된 지하수위 및 지표면 침하량 등을 토대로 수치해석 기법을 적용하여 지질취약대 터널통과에 따른 지반침하거동의 특성을 분석하였다. 지하수 침투-응력연계해석결과, 수치해석결과는 실제 지반침하거동을 잘 반영하는 것으로 분석되었다. 연구결과, 지질취약대인 석회암 공동구간의 터널 굴착에 따른 지반 침하는 급격한 지하수위 하강이 주요 원인인 것으로 분석되었다. 수치해석결과, 지하수위 강하에 의한 토사층 체적감소로 인해 지하수 유출된 이후의 장기적인 아스팔트 지표면 장기 누적침하량은 76~118mm인 것으로 분석되었으며 침하량은 토사층 깊이가 깊을수록 증가하는 양상을 나타냈다.

• 한국지반환경공학회 논문집
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• 제13권4호
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• pp.77-91
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• 2012

최근 우리나라는 국토의 고도 이용과 지역 간의 균형발전을 도모하기 위한 목적으로 택지 및 단지, 도로, 항만 및 공항 등의 건설이 증가하고 있는 추세이다. 현재도 많은 공사들이 연약한 지반에서 실시되고 있다. 이로 인해 건설현장에서 지반의 장기침하, 파괴, 부등침하, 국지적인 구조물 손상 등의 공학적인 문제들이 지속적으로 보고되고 있다. 특히, 연약지반이 비교적 두껍게 발달한 서 남해안 지역과 내륙지역의 연약지반 위에 축조되는 각종 구조물, 도로 등의 경우 필연적으로 하중에 의한 지반의 장기침하가 발생하게 된다. 따라서, 본 연구에서는 기존의 장기침하량 예측기법들인 쌍곡선법, 호시노법, $\sqrt{S}$법, 아사오카법 등의 지역별 적정 분석기법을 검토하는 한편, 일반화된 산정식의 도출을 통한 새로운 예측기법에 대한 연구를 수행하여 토질특성 및 시공조건에 대한 상관관계를 분석하고 장기적인 침하특성과의 연관계수를 도출하였다. 수식의 검증을 위해 16개 지역의 계측자료와 수치해석 결과를 비교 및 분석을 실시하였다.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2008년도 춘계 학술발표회 논문집
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• pp.70-73
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• 2008

연약지반의 깊이차, 연약대 및 경사면 등에 따른 지반침하의 영향에 의해 석탑구조물은 기울어짐, 변형과 균열현상 등이 발생함으로써 석탑구조물의 장기적인 보존에 문제점이 발생되고 있다. 하지만 국내의 경우 연약지반 특성을 고려한 상부 석탑구조물의 거동에 대한 연구는 미비한 실정이다. 따라서 본 연구는 연약지반 특성에 따른 역학적 분석을 통해 연약지반의 깊이차와 기울어짐 발생에 따른 영향을 고려하여 석탑구조물에 끼치는 구조적인 영향을 파악하고, 개별요소해석기법을 통해 연약지반 특성에 따른 석탑구조물의 구조모델링 및 구조해석을 수행하고자 한다.

• Journal of Microbiology and Biotechnology
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• 제30권6호
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• pp.848-855
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• 2020

Land subsidence induced by underground coal mining leads to severe ecological and environmental problems. Arbuscular mycorrhizal fungi (AMF) have the potential to improve plant growth and soil properties. We aimed to assess the effects of AMF on the growth and soil properties of sea buckthorn under field conditions at different reclamation times. Inoculation with AMF significantly promoted the survival rate of sea buckthorn over a 50-month period, while also increasing plant height after 14, 26, and 50 months. Crown width after 14 months and ground diameter after 50 months of inoculation treatment were significantly higher than in the uninoculated treatment. AMF inoculation significantly improved plant mycorrhizal colonization rate and promoted an increase in mycelial density in the rhizosphere soil. The pH and electrical conductivity of rhizosphere soil also increased after inoculation. Moreover, after 26 and 50 months the soil organic matter in the inoculation treatment was significantly higher than in the control. The number of inoculated soil rhizosphere microorganisms, as well as acid phosphatase activity, also increased. AMF inoculation may play an active role in promoting plant growth and improving soil quality in the long term and is conducive to the rapid ecological restoration of damaged mining areas.