• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.371-377
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• 2014

In tissue engineering, a scaffold is a three-dimensional(3D) structure that serves as a template for regeneration the functions of damaged tissues or organs. Among materials for scaffolds, polycaprolactone(PCL) and ${\beta}$-tricalcium phosphate(${\beta}$-TCP) are biodegradable and biocompatible. In this study, we fabricated 3D PCL, blended PCL (60 wt %)/${\beta}$-TCP (40 wt %), and pure ${\beta}$-TCP scaffolds by a multi-head scaffold fabrication system. Scaffolds with a pore size of $600{\pm}20{\mu}m$ was observed by scanning electron microscopy. The effects of 3D PCL, blended PCL (60 wt %)/${\beta}$-TCP (40 wt %) and pure ${\beta}$-TCP scaffolds were analyzed by evaluating their mechanical characteristics. In addition, in an in-vitro study using osteoblast-like saos-2 cells, we confirmed the effects of 3D scaffolds on cellular behaviors such as cell adhesion and proliferation. In summary, the 3D blended PCL (60 wt %)/${\beta}$-TCP (40 wt %) scaffold was found to be suitable for human cancellous bone in terms of its the compressive strength, biocompatibility, and osteoconductivity. Thus, blending PCL and ${\beta}$-TCP could be a promising approach for fabricating 3D scaffolds for effective bone regeneration.

• Journal of the Korean Dietetic Association
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• v.27 no.3
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• pp.191-200
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• 2021

This study was carried out to investigate the effect of the addition of Taraxacum coreamm powder (TCP) (1%, 3%, 5%, 7%) on the quality of pound cake. The specific gravity of the pound cake increased, but the pH of the pound cake significantly decreased with the addition of Taraxacum coreamm powder. The weight of the pound cake slightly increased, whereas the volume and specific loaf volume decreased with the addition of TCP. The texture analysis showed that hardness, chewiness, and gumminess were higher with the addition of TCP than in the control group. The L and a value of the pound cake decreased, whereas the b value increased with the addition of TCP. The moisture content and the DPPH radical scavenging activities of the pound cake increased as percentages of TCP significantly increased.

• The Journal of Internal Korean Medicine
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• v.43 no.4
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• pp.514-528
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• 2022

Objective: To examine the effects of Trichosanthes kirilowii Maximowicz extract (TE) and Trichosanthes kirilowii Maxi mowicz Cheonghyeol Plus Phellinus linteus Cheonghyeol plus (TCP) on anti-inflammatory factor expression in human umbilical vein endothelial cells (HUVECs). Methods: HUVECs were activated with TNF-α and then treated with TE and TCP. The expression levels were then measured for intracellular genes (KLF2, eNOS, MCP-1, ICAM-1, and VCAM-1), proteins (KLF2, eNOS, MCP-1, ICAM-1, VCAM-1, ERK, and JNK, p38), and extracellular biomarkers (ICAM-1, VCAM-1, and MCP-1). Results: 1. TCP at concentrations of 100 ㎍/mL or greater significantly increased the expression of KLF2 and eNOS intracellular genes and significantly decreased the expression of ICAM-1, VCAM-1, and MCP-1 genes compared to the control group. 2. TCP at concentrations of 100 ㎍/mL or greater significantly increased the expression of KLF2, eNOS proteins compared to the control group, and significantly reduced the expression of VCAM-1, ICAM-1, MCP-1, ERK, and p38 proteins. However, JNK protein phosphorylation showed no significant change compared to the control group. 3. TCP at concentrations of 100 ㎍/mL or more significantly decreased the production of MCP-1, ICAM-1, and VCAM-1 extracellular biomarkers compared to the control group. 4. TE at a concentration of 100 ㎍/mL did not cause any significant change in the expression of intracellular genes or proteins, in the production of the extracellular biomarker MCP-1, or in the amount of JNK protein compared to the control group. Other intracellular genes, proteins, and extracellular biomarker expression showed the same trend as observed with TCP exposure. Conclusion: This study experimentally confirmed that TE and TCP could be effective in preventing or inhibiting various inflammatory vascular diseases due to their anti-inflammatory effects.

• The Journal of the Korea Contents Association
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• v.9 no.8
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• pp.73-83
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• 2009

TCP(Transmission Control Protocol) is currently used connection-oriented protocol as a typical transport layer protocol in the Internet. However, it has deficiency not be able to communicate with other TCP entities when any link included in the path is down because of single-homing on single path. SCTP(Stream Control Transmission Protocol) suggested as the new transport layer protocol supports multi-homing feature, which provides several paths between source and destination. It can communicate with other SCTP entities using alternate path even when any link on the primary path is down. This paper aims to measure and analyze the multi-homing effect of SCTP over TCP in case of link-down using NS-2 simulator. We classify SCTP into $SCTP_{single-homing}$ and $SCTP_{multi-homing}$ because SCTP with single-homing can also be used like TCP. We measured throughput and bandwidth utilization varying link-down duration, bandwidth, and RTT(round trip time), Simulation results show that throughput of $SCTP_{multi-homing}$ is more than that of TCP by 18 % on average. It is also shown that $SCTP_{multi-homing}$ on varying RTT and bandwidth increases the throughput of TCP by 'l7% and 9% on average, respectively in the link-down environment. In above cases, more or less difference between $SCTP_{single-homing}$ and TCP on throughput and bandwidth utilization was found To summarize, multi-homing effect of SCTP over TCP on throughput is about 18 % on average in the link-down environment This experimental result can be used as the benchmark in order to estimate the multi-homing effect of SCTP over TCP when the link-down happens in the real Internet.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1273-1281
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• 2014

Tissue engineering is an emerging research field that has the potential to restore, regenerate and repair damaged bone tissue and organs. Tricalcium phosphate and hydroxyapatite biomaterials-based calcium phosphate are excellent materials that have both osteoconduction and biocompatibility for bone tissue regeneration. In this study, solution structures were successfully fabricated using a fused deposition modeling system based on deposition and heating devices. The morphology characteristics of the bioceramic scaffolds sintered at a temperature of $1,300^{\circ}C$ were analyzed by scanning electron microscopy. The effects of various blended TCP/HA ratio on the microstructure and shrinkage were studied. The mechanical properties of the scaffolds were measured using a compression testing machine from stress-strain curves on the crosshead velocity of 1 mm/min. The fabricated scaffolds were evaluated by cell proliferation tests of MG-63 cells. The results of this study suggest that the blended TCP(75 wt%)/HA(25 wt%) scaffold is an appropriate scaffold for bone tissue regeneration.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.202-209
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• 2004

Hydroxyapatite(HA)/TiO$_2$ composite powders were prepared by mixing of spherical TiO$_2$ (10-15 nm, 500 nm) and needle-shaped HA (50-70 nm, 120-250 nm) powders which had been synthesized through precipitation, sol-gel and hydrothermal methods. From the three types of starting composite powders (HA/TiO$_2$ wt% of 75/25, 50/50, and 25/75), dense $\beta$-TCP/TiO$_2$ composites were prepared by hot-pressing at 800-100$0^{\circ}C$ for 30 min under the pressure of 30 ㎫ in Af atmosphere. The $\beta$-TCP/TiO$_2$ composites showed different microstructures and sintering densities depending on their powder morphology, composition and sintering temperature. With increasing the sintering temperature and the content of TiO$_2$, sintered density was increased and microstructure became more homogeneous.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.3
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• pp.31-39
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• 2015

This paper presents the static and kinematic positioning accuracy by the real-time GPS positioning modes of the low-cost GPS receivers using NTRIP-based augmentation service. For this, acquires both the raw measurements data of the field tests by LEA 6T GPS module of u-blox AG, and correction communication via NTRIP caster with RTKLIB as an open source program for GNSS solution. With computing the positions of the check points and road tracks by six kinds of GPS positioning modes which are Single, SBAS, DGPS, PPP, RTK, and TCP/IP_RTK, compared these results to the reference position of the check points. The position error average and rmse of the static test by GPS L1 RTK surveying showed $N=0.002m{\pm}0.001m$, $E=0.004m{\pm}0.001m$ in horizontal plane, and $h=-0.116m{\pm}0.003m$ in vertical, these results are very closed to the coordinates with the geodetic receiver. Especially, in case of the kinematic test with obstacles located on both sides of road, the computed track with ambiguity fixing showed very similar trajectory considerably from VRS network RTK mode. And also, evaluate and verify the performance of the TCP/IP_RTK mode developed based on TCP/IP protocol.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1508-1516
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• 2017

Multipath TCP (MPTCP) is a transport layer protocol that supports multipath transmission. If a bufferbloat occurs in one of the subflows of MPTCP, HoL blocking occurs at the receiver due to the difference in packet arrival time among paths. In MPTCP, HoL blocking degrades not only the performance of the path where bufferbloat occurs, but also the performance of other paths. In this paper, we propose a bandwidth measurement based scheduler to solve this problem. Bandwidth measurement based scheduler is designed to measure the bandwidth of each subflow and to perform packet scheduling based on it. In order to verify the proposed scheduler, we implemented the proposed scheduler in the Linux kernel and constructed a testbed in which bufferbloat occurs. Experimental results show that the proposed scheduler has better performance than the legacy MPTCP in bufferbloat environment.

• The KIPS Transactions:PartA
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• v.16A no.2
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• pp.113-124
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• 2009

With increasing multicore system, much effort has been put on the performance improvement of its application. Because multicore system has multiple processing devices in one system, its processing power increases compared to the single core system. However in many cases the advantages of multicore can not be exploited fully because the existing software and hardware were designed to be suitable for single core. When the existing software runs on multicore, its performance improvement is limited by the bottleneck of sharing resources and the inefficient use of cache memory on multicore. Therefore, according as the number of core increases, it doesn't show performance improvement and shows performance drop in the worst case. In this paper we propose a method of performance improvement of multicore system by applying Flow-Level Parallelism to the existing TCP/IP network application and operating system. The proposed method sets up the execution environment so that each core unit operates independently as much as possible in network application, TCP/IP stack on operating system, device driver, and network interface. Moreover it distributes network traffics to each core unit through L2 switch. The proposed method allows to minimize the sharing of application data, data structure, socket, device driver, and network interface between each core. Also it allows to minimize the competition among cores to take resources and increase the hit ratio of cache. We implemented the proposed methods with 8 core system and performed experiment. Experimental results show that network access speed and bandwidth increase linearly according to the number of core.

• Journal of the Korean Vacuum Society
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• v.12 no.S1
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• pp.10-14
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• 2003

Coatings of hydroxyapatite (HA) and tricalcium phosphate/HA (TCP/HA) on titanium were fabricated by ion beam assisted deposition (IBAD). Significant effect of the Ca-P coatings on human Gingival Fibroblasts (HGFs) attachment and formation of type I collagen were found by using immunofluorescence microscope. TCP/HA and HA coatings exerted more HGFs attachment and collagen I formation. Comparing with HA coating, TCP/HA coating exhibited better responses during the late period of the tests. This investigation indicated that this surface modification method may enhance the biological seal at the cervical level of the titanium dental implants.