• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 추계 학술발표회
• /
• pp.498-507
• /
• 2008

The mixture of bentonite powder and water is generally used to maintain the stability of excavation surface during the construction of vertical cutoff walls. The filter cake on the sidewall surface is the result of filtration of slurry into the adjacent soil formation. The filter cake is believed to have a very low hydraulic conductivity compared to that of the cutoff wall. This paper evaluates hydraulic conductivities of bentonite filter cakes set up with three types of bentonites under various pressure levels. A modified fluid loss test was employed in this experiment. Theory of filtration process was reviewed to explain the procedure in the present experiment. Hydraulic conductivity of the filter cakes with consideration of the filter medium resistance was evaluated. The results of the experiment with two calculation methods and discussion are presented to show the efficiency of the modified fluid loss test.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 추계 학술발표회
• /
• pp.1502-1511
• /
• 2008

The mixture of bentonite powder and water is generally used to maintain the stability of excavation surface during the construction of vertical cutoff walls. The filter cake on the sidewall surface is the result of filtration of slurry into the adjacent soil formation. The filter cake is believed to have a very low hydraulic conductivity compared to that of the cutoff wall. This paper evaluates hydraulic conductivities of bentonite filter cakes set up with three types of bentonites under various pressure levels. A modified fluid loss test was employed in this experiment. Theory of filtration process was reviewed to explain the procedure in the present experiment. Hydraulic conductivity of the filter cakes with consideration of the filter medium resistance was evaluated. The results of the experiment with two calculation methods and discussion are presented to show the efficiency of the modified fluid loss test.

• Molecules and Cells
• /
• 제44권8호
• /
• pp.591-601
• /
• 2021

Cilia are highly specialized organelles that extend from the cell membrane and function as cellular signaling hubs. Thus, cilia formation and the trafficking of signaling molecules into cilia are essential cellular processes. TULP3 and Tubby (TUB) are members of the tubby-like protein (TULP) family that regulate the ciliary trafficking of G-protein coupled receptors, but the functions of the remaining TULPs (i.e., TULP1 and TULP2) remain unclear. Herein, we explore whether these four structurally similar TULPs share a molecular function in ciliary protein trafficking. We found that TULP3 and TUB, but not TULP1 or TULP2, can rescue the defective cilia formation observed in TULP3-knockout (KO) hTERT RPE-1 cells. TULP3 and TUB also fully rescue the defective ciliary localization of ARL13B, INPP5E, and GPR161 in TULP3 KO RPE-1 cells, while TULP1 and TULP2 only mediate partial rescues. Furthermore, loss of TULP3 results in abnormal IFT140 localization, which can be fully rescued by TUB and partially rescued by TULP1 and TULP2. TUB's capacity for binding IFT-A is essential for its role in cilia formation and ciliary protein trafficking in RPE-1 cells, whereas its capacity for PIP₂ binding is required for proper cilia length and IFT140 localization. Finally, chimeric TULP1 containing the IFT-A binding domain of TULP3 fully rescues ciliary protein trafficking, but not cilia formation. Together, these two TULP domains play distinct roles in ciliary protein trafficking but are insufficient for cilia formation in RPE-1 cells. In addition, TULP1 and TULP2 play other unknown molecular roles that should be addressed in the future.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 추계학술대회 초록집
• /
• pp.86.2-86.2
• /
• 2010

In order to improve polymer electrolyte membrane fuel cell (PEMFC) durability, the durability of membrane electrode assemblies (MEA), in which the electrochemical reactions actually occur, is one of the vital issues. Many articles have dealt with catalyst layer degradation of the durability-related factors on MEAs in relation to loss of catalyst surface area caused by agglomeration, dissolution, migration, formation of metal complexes and oxides, and/or instability of the carbon support. Degradation of catalyst layer during long-term operation includes cracking or delamination of the layer which result either from change in the catalyst microstructure or loss of electronic or ionic contact with the active surface, can result in apparent activity loss in the catalyst layer. Membrane degradation of the durability-related factors on MEAs can be caused by mechanical or thermal stress resulting in formation of pinholes and tears and/or by chemical attack of hydrogen peroxide radicals formed during the electrochemical reactions. All of these effects, the mechanical damage of membrane and degradation of catalyst layers are more facilitated by uneven stress or improper MEA fabrication process. In order to improve the PEMFC durability, therefore, it is most important to minimize the uneven stress or improper MEA fabrication process in the course of the fabrication of MEA. We analyzed the effects of the MEA fabrication condition on the PEMFC durability with MEA produced using CCM (catalyst coated membrane) method. This paper also investigated the effects of MEA fabrication condition on the PEMFC durability by adding additional treatment process, hot pressing and pressing, on the MEA produced using CCM method.

• 대한한방내과학회지
• /
• 제43권6호
• /
• pp.1134-1148
• /
• 2022

Purpose: We evaluated whether Spatholobus suberectus extract (SSE) can be used as a means of preventing and treating osteoporosis by measuring its effect on osteoclast differentiation, gene expression, and bone resorption. Methods: SSE was used to examine the effect on RAW 264.7 cells stimulated with RANKL to induce bone resorption. The inhibitory effect of TRAP formation and the expression of the bone resorption factors TRAP, cathepsin K, and MMP-9 during differentiation were measured. The effects on the differentiation-related factors NFATc and TRAIL and on the expression of OC-STAMP, DC-STAMP, ATP6v0d2, MITF, c-Fos, and inflammation-related factors were also evaluated. The effect on bone resorption was evaluated by culturing RANKL-treated osteoclasts on artificial bone fragments and observing the resulting resorption traces. The effect on bone damage in experimental animals was also measured. Results: SSE inhibited the differentiation of RANKL-stimulated osteoclasts into osteoclasts and suppressed the expression of cathepsin K, TRAP, MMP-9, NFATc1, TRAIL, MITF, OC-STAMP, DC-STAMP, ATP6v0d2, and c-Fos genes. Bone pore formation due to osteoclast action was also inhibited, and LPS-induced bone loss was suppressed in animal experiments. Conclusions: SSE could be useful for the prevention or treatment of osteoporosis by inhibiting osteoclast differentiation and bone resorption and suppressing bone loss induced in experimental animals. However, studies of larger populations are required.

• Journal of Periodontal and Implant Science
• /
• 제44권1호
• /
• pp.39-47
• /
• 2014

Purpose: Peri-implantitis, a clinical term describing the inflammatory process that affects the soft and hard tissues around an osseointegrated implant, may lead to peri-implant pocket formation and loss of supporting bone. However, this imprecise definition has resulted in a wide variation of the reported prevalence; ${\geq}10%$ of implants and 20% of patients over a 5- to 10-year period after implantation has been reported. The individual reporting of bone loss, bleeding on probing, pocket probing depth and inconsistent recording of results has led to this variation in the prevalence. Thus, a specific definition of peri-implantitis is needed. This paper describes the vast variation existing in the definition of peri-implantitis and suggests a logical way to record the degree and prevalence of the condition. The evaluation of bone loss must be made within the concept of natural physiological bony remodelling according to the initial peri-implant hard and soft tissue damage and actual definitive load of the implant. Therefore, the reason for bone loss must be determined as either a result of the individual osseous remodelling process or a response to infection. Methods: The most current Papers and Consensus of Opinion describing peri-implantitis are presented to illustrate the dilemma that periodontologists and implant surgeons are faced with when diagnosing the degree of the disease process and the necessary treatment regime that will be required. Results: The treatment of peri-implantitis should be determined by its severity. A case of advanced peri-implantitis is at risk of extreme implant exposure that results in a loss of soft tissue morphology and keratinized gingival tissue. Conclusions: Loss of bone at the implant surface may lead to loss of bone at any adjacent natural teeth or implants. Thus, if early detection of peri-implantitis has not occurred and the disease process progresses to advanced peri-implantitis, the compromised hard and soft tissues will require extensive, skill-sensitive regenerative procedures, including implantotomy, established periodontal regenerative techniques and alternative osteotomy sites.

• 천문학회지
• /
• 제36권3호
• /
• pp.167-175
• /
• 2003

There is accumulating evidence for a strong link between nuclear starbursts and AGN. Molecular gas in the central regions of galaxies plays a critical role in fueling nuclear starburst activity and feeding central AGN. The dense molecular ISM is accreted to the nuclear regions by stellar bars and galactic interactions. Here we describe recent observational results for the OB star forming regions in M51 and the nuclear star burst in Arp 220 - both of which have approximately the same rate of star formation per unit mass of ISM. We suggest that the maximum efficiency for forming young stars is an Eddington-like limit imposed by the radiation pressure of newly formed stars acting on the interstellar dust. This limit corresponds to approximately 500 $L_{\bigodot} / M_{\bigodot}$ for optically thick regions in which the radiation has been degraded to the NIR. Interestingly, we note that some of the same considerations can be important in AGN where the source of fuel is provided by stellar evolution mass-loss or ISM accretion. Most of the stellar mass-loss occurs from evolving red giant stars and whether their mass-loss can be accreted to a central AGN or not depends on the radiative opacity of the mass-loss material. The latter depends on whether the dust survives or is sublimated (due to radiative heating). This, in turn, is determined by the AGN luminosity and the distance of the mass-loss stars from the AGN. Several AGN phenomena such as the broad emission and absorption lines may arise in this stellar mass-loss material. The same radiation pressure limit to the accretion may arise if the AGN fuel is from the ISM since the ISM dust-to-gas ratio is the same as that of stellar mass-loss.

• Structural Engineering and Mechanics
• /
• 제61권4호
• /
• pp.527-538
• /
• 2017

The evaluation of the loss-of-support conditions of frictional beam-to-column connections using simplified numerical models describing the transverse response of a portal-like structure is presented in this paper considering the effects of the seismic-hazard disaggregation. Real earthquake time histories selected from European Strong-motion Database (ESD) are used to show the effects of the seismic-hazard disaggregation on the beam loss-of-support conditions. Seismic events are classified according to different values of magnitudes, epicentral distances and soil conditions (stiff or soft soil) highlighting the importance of considering the characteristics of the seismic input in the assessment of the loss-of-support conditions of frictional beam-to-column connections. A rigid and an elastic model of a frame of a precast industrial building (2-DoF portal-like model) are presented and adopted to find the minimum required friction coefficient to avoid sliding. Then, the mean value of the minimum required friction coefficient with an epicentral distance bin of 10 km is calculated and fitted with a linear function depending on the logarithm of the epicentral distance. A complete parametric analysis varying the horizontal and vertical period of vibration of the structure is performed. Results show that the loss-of-support condition is strongly influenced by magnitude, epicentral distance and soil conditions determining the frequency content of the earthquake time histories and the correlation between the maxima of the horizontal and vertical components. Moreover, as expected, dynamic characteristics of the structure have also a strong influence. Finally, the effect of the column nonlinear behavior (i.e. formation of plastic hinges at the base) is analyzed showing that the connection and the column are a series system where the maximum force is limited by the element having the minimum strength. Two different longitudinal reinforcement ratios are analyzed demonstrating that the column strength variation changes the system response.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제23권3호
• /
• pp.43-50
• /
• 2018

In a previous study, the feasibility of four materials (bentonite, steelmaking slag, lime and organic compost) to induce soil aggregate formation was assessed and the mixtures of organic compost and lime were chosen as most effective amendments in terms of cost benefit. This work is a subsequent study to evaluate the effectiveness of those amendments in reducing soil loss in $15^{\circ}$ sloped agricultural area by using rainfall simulation test. Three different soils were treated with two conditions of organic compost/lime mixtures (2% + 2%, 3% + 1%, w/w). In the amended soils, soil fertility was increased due to the increase of CEC, T-N, and T-P. During the rainfall simulation, suspended solid in run-off water from amended soil were reduced by 43% ~ 78%. When the content of organic compost was higher than that of lime, reduction of soil loss was also increased by 67% ~ 78%. Sediment discharge was also decreased by 72% ~ 96% in the amended soil. Similar to the suspended solid analysis, higher organic compost content led to more reduction of soil discharging, which implies organic compost is more effective than lime in reducing soil loss. The overall result suggests that the mixtures of organic compost and lime could be used as amendment materials to reduce soil loss in sloped farmland.

• 대한소아치과학회지
• /
• 제42권1호
• /
• pp.53-61
• /
• 2015

소아치과 임상에서 기성금속관 수복은 매우 높은 활용성과 사용빈도에도 불구하고 완벽하고 정밀한 수복이 쉽지 않은 항목으로 판단된다. 불량한 변연 적합, 변연부 치태 침착, 인접 영구치의 맹출 장애, 접착제 소실 및 이차 우식, 부적절한 지대치 삭제, 교합면 천공 등이 임상적으로 흔히 관찰되는 문제점들이다. 본 연구는 기성금속관이 장착된 상태로 발치된 유구치를 대상으로 수복 상태를 평가해 봄으로써, 빈번한 결함과 착오들을 찾아낼 목적으로 시도되었다. 부산대학교 치과병원 소아치과에서 발치된 기성금속관 수복 유구치 97개를 대상으로 육안적 평가와 micro-computed tomography(micro-CT) 영상을 분석하였다. 변연 적합도, 접착제 소실, 이차우식, 교모성 천공, 변연부 연마 결함, 선반(ledge) 형성 등의 항목으로 수복상태를 평가하여, 다음과 같은 결과를 얻었다. 조사항목들을 대상치아 기준으로 보았을 때, 접착제 소실이 가장 빈번하였으며(98%), 뒤를 이어 이차우식(42.3%), 변연부 연마 결함(41.2%), 선반(ledge) 형성(29.9%), 교모성 천공(17.5%)의 순으로 나타났다. 변연 간격이 클수록 접착제 소실이 증가하는 경향을 보였고, 접착재 소실은 변연 간격 및 이차 우식과 유의한 상관성을 보였다. 평균 변연간격은 $0.31{\pm}0.26mm$ 였으며, 상악 제2 유구치에서 가장 크게 나타났다. 변연이 백악법랑경계 상방에 위치하는 경우가 가장 많았고, 변연이 치관 상방에 위치할수록 변연 간격은 작게 나타났다(p < 0.05).