• 산업기술연구
• /
• 제20권A호
• /
• pp.123-129
• /
• 2000

As materials on the river bed have been changing through erosion, transportation and accumulation, so does the waterway's section. So many bridges have nowadays been constructed to the same direction as water flows. However further researches are still needed on the scours of succession row piers and multiple row piers. Analyzing them through hydraulic stimulation experiments, this study deals with the scour character with the change of diameters in row piers which have been built in the identical direction of water flow and also the part-scour character change in multiple row piers.

• Wind and Structures
• /
• 제29권2호
• /
• pp.99-110
• /
• 2019

This paper provides a simple numerical method to determine the optimal parameters of tuned mass damper (TMD) and viscoelastic dampers (VEDs) in frame structure for wind vibration control considering the soil-structure interation (SSI) effect in frequency domain. Firstly, the numerical model of frame structure equipped with TMD and VEDs considering SSI effect is established in frequency domain. Then, the genetic algorithm (GA) is applied to obtain the optimal parameters of VEDs and TMD. The optimization process is demonstrated by a 20-storey frame structure supported by pile group for different soil conditions. Two wind resistant systems are considered in the analysis, the Structure-TMD system and the Structure-TMD-VEDs system. The example proves that this method can quickly determine the optimal parameters of energy dissipation devices compared with the traditional finite element method, thus is practically valuable.

• 대한치과기공학회지
• /
• 제42권1호
• /
• pp.9-16
• /
• 2020

Purpose: The purpose of this study was to compare the marginal and internal fit of lithium disilicate ceramic inlay produced by heat pressing that inlay pattern made by subtractive manufacturing and additive manufacturing method. Methods: A mandibular lower first molar that mesial occlusal cavity (MO cavity) die was prepared. After fabricating an epoxy resin model using a silicone impression material, epoxy resin die was scanned with a dental model scanner to design an MO cavity inlay. The designed STL pile was used to fabricate wax patterns and resin patterns, and then lithium disilicate ceramic inlays were fabricated using hot-press method. For the measurement of the marginal and internal gap of the lithium disilicate, silicone replica method was applied, and gap was measured through an optical microscope (x 80). Data were tested for significant differences using the Mann-Whitney Utest. Results: The marginal fit was 103.56±9.92㎛ in the MIL-IN group and 81.57±9.33㎛ in the SLA-IN group, with a significant difference found between the two groups (p<0.05). The internal fit was 120.99±17.52㎛ in the MIL-IN group and 99.18±6.65㎛ in the SLA-IN group, with a significant difference found between the two groups (p<0.05). Conclusion: It is clinically more appropriate to apply the additive manufacturing than subtractive manufacturing method in producing lithium disilicate inlay using CAD/CAM system.

• 설비공학논문집
• /
• 제25권1호
• /
• pp.28-36
• /
• 2013

The aim of this study is to evaluate the performance of the GHP system with 45 cast-in-place energy piles(CEP) for a commercial building. In order to demonstrate the feasibility of a sustainable performance of the system, transient simulations were conducted over 1-year and 20-year periods, respectively. The 1-year simulation results showed that the maximum and minimum temperatures of brine returning from the CEPs were $23.91^{\circ}C$ and $6.66^{\circ}C$, which were in a range of design target temperatures. In addition, after 20 years' operation, these returning temperatures decreased to $21.24^{\circ}C$ and $3.68^{\circ}C$, and finally reached to stable state. Annual average extraction heat of cast-in-place energy piles was 94.3 MWh and injection heat was 65.7 MWh from the 20 years of simulation results. Finally, it is expected this GHP system can operate with average heating SPF of more than 3.45 for long-term.

• Acta Via Serica
• /
• 제8권2호
• /
• pp.1-24
• /
• 2023

The art of carpet weaving is the most habitual form of traditional art in Azerbaijan, it reflects a rich inner world and occupies a special place in the history of a national culture's development. The Azerbaijani carpet has always stood out for its plots, ornaments, compositions, and high quality and the Azerbaijani people, faithful to their spiritual values, have protected and developed it throughout the centuries. In this article, several Ganja-Gazakh-type carpets from the Azerbaijan National Carpet Museum collection and their artistic and technical characteristics are discussed. Specimens of material, sacred language, and ornamentation are considered. The deepest meaning is embodied in tamga in particular. Tamga is a unique phenomenon serving as an amulet, lineage sign, and self-identification of Turkic peoples. The Gazakh carpets of the Ganja-Gazakh type cover the Gazakh region of Azerbaijan, the Borchali region of Georgia, and the Goycha Lake region of Armenia. Karapapakh Azerbaijani Turks have inhabited these areas since ancient times. Tarakama (nomads) are often equated with the name Karapapakh (black hat). One of the densely populated regions of Tarakama is Gazakh. Gazakh, Garagoyunlu, Salahli, Shikhli, Kamarli, Damirchilar, Gaymagli, Goycali, Daghkasaman, Oysuzlu, Gachagan, and pile carpets with different compositions are woven in the Gazakh carpet weaving center. Large, simple in form, step-shaped or hook-like medallions, horn-shaped patterns, animal images, and stamps with symbols of ancient Turkic tribes characterize the Gazakh carpet weaving group.

• 한국지반환경공학회 논문집
• /
• 제8권3호
• /
• pp.19-25
• /
• 2007

쇄석말뚝은 느슨한 사질토지반이나 점토지반에 치환법에 의해 다져진 자갈이나 쇄석을 연약한 지반에 삽입하여 개량하는 공법이다. 쇄석말뚝 공법은 흙과 말뚝 접촉면에서 압밀거동이 다양한 인자에 의해 영향을 받게 되어 정량적인 해석에 많은 어려움이 있다. 본 연구에서는 재하시험을 통해 선단지지 군말뚝의 거동에 대한 다양한 인자의 영향을 조사하였다. 궁극적으로 연약지반의 개량 특성과 설계인자의 영향력을 PR값을 사용하여 평가하였다. 실험결과와 계산된 PR 값으로부터 쇄석말뚝의 침하거동이 근입비나 매트의 설치여부 보다는 말뚝의 직경이나 복합지반의 치환율에 의해 영향을 받고 있음을 알 수 있다.

• 한국지반공학회논문집
• /
• 제17권2호
• /
• pp.85-93
• /
• 2001

본 논문에서는 연약지반에 시공된 교대말뚝기초에 인접하여 성토하중이 재하될 때 발생하는 측방유동의 발생메커니즘을 규명하기 위해 3차원 유한요소해석을 수행하였다. 본 수치해석에서는 점성토 지반과 점성토-사질토 지반 그리고 사질토-점성토 지반에 선단지지된 강관말뚝에 대하여 성토하중 크기(q=20, 75, 100kPa)와 말뚝두부조건(변위구송, 회전구속) 그리고 말뚝중심간격(s=2.5d, 5.0d, 7.0d, 단독말뚝)에 따라 측방유동압의 분포형태와 크기를 분석하였다. 그 결과 측방유동압의 분포형태는 교대말뚝기초의 수평변위와 유사한 형태로 나타났으며 측방유동압의 크기는 배면 성토하중의 크기에 대한 비로써 결정할 수 있었다. 그리고 점성토 지반과 점성토-사질토 지반의 경우, 측방유동압의 분포형태와 크기는 말뚝두부조건에 가장 큰 영향을 받는 반면 사질토-점성토 지반의 경우에는 말뚝두부조건보다는 토층조건에 가장 큰 영향을 받는 것으로 분석되었다. 본 연구결과를 토대로 연약지반에 시공된 교대말뚝기초의 측방유동에 대한 설계 및 해석시 지침자료로서 측방유동압의 분포형태와 크기를 추천.제안한다.

• 한국전산구조공학회논문집
• /
• 제32권3호
• /
• pp.155-164
• /
• 2019

이 연구에서는 기초의 종류에 따라 지반-구조물 상호작용(SSI) 효과가 LNG 저장탱크의 지진응답해석에 미치는 효과를 분석하였다. 이를 위하여 직경 71m인 LNG 탱크와 기반암 위 점토지반의 깊이가 30m인 지반조건을 고려하였다. 그리고 기초형식으로 네 가지(얕은 기초, 말뚝지지 전면기초, 말뚝기초(지표면 접촉식, 부유식)를 고려하였다. 지반의 비선형성은 자유장 지반에 대하여 등가선형화기법으로 고려되었다. 또한, 말뚝기초의 시공과정에서 발생하는 동다짐 효과에 대해서도 분석하였다. SSI 해석을 위하여 진동수영역 해석프로그램인 KIESSI-3D를 이용하였다. 지반-구조물 상호작용 해석을 통해 LNG 저장탱크의 외조 벽체 쉘의 응력과 내조탱크의 밑면전단력 및 전도모멘트를 구하였다. 해석결과로부터 다음과 같은 결론을 얻을 수 있었다: (1) 고정 기초해석에 의한 외조와 내조탱크의 지진응답이 SSI 효과로 인한 지진응답보다 매우 컸다. (2) SSI의 효과가 내조탱크와 외조탱크의 동적응답에 미치는 영향은 기초의 형식에 따라 다르게 나타난다. (3) 말뚝지지 전면기초에서 동다짐 효과에 의한 구조물 응답의 변화는 약 10%로서 무시할 수 없을 정도로 큰 것으로 나타났다.

• Geomechanics and Engineering
• /
• 제5권1호
• /
• pp.17-36
• /
• 2013

Settlement of the piled raft can be estimated even after years of completing the construction of any structure over the foundation. This study is devoted to carry out numerical analysis by the finite element method of the consolidation settlement of piled rafts over clayey soils and detecting the dissipation of excess pore water pressure and its effect on bearing capacity of piled raft foundations. The ABAQUS computer program is used as a finite element tool and the soil is represented by the modified Drucker-Prager/cap model. Five different configurations of pile groups are simulated in the finite element analysis. It was found that the settlement beneath the piled raft foundation resulted from the dissipation of excess pore water pressure considerably affects the final settlement of the foundation, and enough attention should be paid to settlement variation with time. The settlement behavior of unpiled raft shows bowl shaped settlement profile with maximum at the center. The degree of curvature of the raft under vertical load increases with the decrease of the raft thickness. For the same vertical load, the differential settlement of raft of ($10{\times}10m$) size decreases by more than 90% when the raft thickness increased from 0.75 m to 1.5 m. The average load carried by piles depends on the number of piles in the group. The groups of ($2{\times}1$, $3{\times}1$, $2{\times}2$, $3{\times}2$, and $3{\times}3$) piles were found to carry about 24%, 32%, 42%, 58%, and 79% of the total vertical load. The distribution of load between piles becomes more uniform with the increase of raft thickness.

• 한국지반공학회논문집
• /
• 제27권4호
• /
• pp.33-41
• /
• 2011

서 김해평야에 위치하는 연장 2km의 철도제방은 정규압밀점토인 연약지반 상에 건설되었다. 연직 배수재를 타입하고 단계시공으로 1단계의 시공을 한 직후에 제방은 종방향 균열이 생겨 원호활동의 징조가 나타났다. 이 단계에서 piled raft로 설계변경하고 제방을 완공하였다. 여러 측점에 다양한 계측기를 설치하여 제방 시공 중 piled raft의 거동을 관찰하였다. 이 결과를 정리하여 piled raft 기초의 안전성을 분석한 결과를 이 논문에 기술하였다. 말뚝 무리가 마찰말뚝으로 작용할 때에는 piled raft 기초는 정규압밀점토에서도 안전하고 경제적인 설계가 될 수 있다는 것을 계측결과로 부터 알게 되었다.