• 멤브레인
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• 제31권3호
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• pp.219-227
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• 2021

분자각인막(MIM)은 특정 분자의 결합자리를 갖고 있는 다공성 고분자 막이다. 비용매유도 상분리(NIPS)법을 사용하여 분자각인막의 지지체로 사용될 P(AN-co-MA) 비대칭막을 제조하고, 여기에 표면 각인법을 적용하여 광활성 이니퍼터 도입과 photo-grafting을 통해 라이소자임 분자각인막을 제조하였다. P(AN-co-MA) 비대칭막을 3-chloropropyltrimethoxysilane과 광활성 이니퍼터 dithiocarbamate로 개질하고, acrylamide 단량체, N,N'-methylenebisacrylamide 가교제, 라이소자임 주형분자 혼합액을 UV 조사 환경에서 혼성중합 시켜 MIM을 제조하였다. 제조된 MIM의 FT-IR과 FE-SEM 및 EDS 분석을 실시한 결과 P(AN-co-MA) 막은 비대칭 단면 구조이었고 표면에 이니퍼터 그룹이 잘 결합되어 있어 MIM이 성공적으로 제조되었다. 제조공정의 변수 조절을 통해 라이소자임의 흡착량이 비각인막(NIM)에 비해 13배 큰 값인 2.7 mg/g을 갖는 P(AN-co-MA) 기반 MIM이 제조되었으며, 막여과 실험을 통해 라이소자임에 대한 오발부민의 투과선택도를 측정한 결과 MIM은 라이소자임의 선택적 결합력이 우수하였다.

• 약학회지
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• 제37권4호
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• pp.356-361
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• 1993

A sensitive method for the determination of methamphetamine(MA) and amphetamine(AM) in hair was developed by gas chromatography/mass spectrometry using stable isotope-labeled internal standards, amphetamine-d$_{5}$ and methamphetamine-d$_{5}$. Hair sample was washed with MeOH, incubated with MeOH(I% HCI) overnight at $37^{\circ}C$ while stirring and extracted using solid phase extraction column on a vacuum manifold. The extract obtained was pentafluoropropionated, and applied to GC/MS. The calibration curves of MA and AM were linear from 2.5 to 250 ng (r>0.99 for both). The limit of detection was 0.1 ng/mg in hair and cut-off level was set at 0.25 ng/mg for both. Hair samples of 27 MA abusers showed positive results in the range 0.7 to 106.8 ng/mg. AM, its metabolite, was detected in 20 out of 27 samples. The ratio of MA versus AM was 4.6~38.3 in specimens. Hair analysis for methamphetamine by GC/MS is an effective method for identifying long-term drug abusers.

• 한국멀티미디어학회논문지
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• 제12권12호
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• pp.1769-1777
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• 2009

With the advent of the ubiquitous technology age, the progress of network technology has enabled a robust sensor communication, not just in cities, but also in poor surroundings such as deserts, polar regions, or underwater environments. In this paper, we propose a Multiple Acknowledgement (MA) technique to replace the conventional Automatic Repeat request (ARQ) technique. The MA mechanism is to send an Ack to many receivers simultaneously. The CH (master, coordinator) of the unit cluster broadcasts a Beacon frame where Ack information of the previously transmitted data is included. This technique can reduce the number of transmissions and overhead significantly. The proposed technique is a scheme improving the efficiency of an underwater sensor network where the uplink data transmission is the mainstream. The Performance of the ARQ, Block Ack, Pervasive Block Ack and the proposed method were compared with one another and analyzed. The proposed method showed significant performance improvement as compared with the ARQ, BA, and PBA in its channel efficiency.

• 한국재료학회지
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• 제16권6호
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• pp.341-345
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• 2006

[ $Ni_2Si$ ] mixed powders were mechanically alloyed by a ball mill and then processed by hot isostatic pressing (HIP) and spark plasma sintering (SPS). In the powder that was mechanically alloyed for 15minutes(MA 15 min), only Ni and Si were observed but in the powder that was mechanically alloyed for 30minutes(MA 30 min), $Ni_2Si$, Ni and Si were mixed together. Some of the MA 15 min powder and MA 30 min powder were processed by HIP under pressure of 150MPa at the temperature of $1000^{\circ}C$ for two hours and some of them were processed by SPS under pressure of 60 MPa at the temperature of $1000^{\circ}C$ for 60 seconds. Both methods completely compounded the powders to $Ni_2Si$. The maximum density of sintered lumps by HIP method was 99.5% and the maximum density of the sintered lump by SPS method was 99.3%. with the hardness of HRc 66 with the hardness of HRc 63. Therefore, the SPS method that can sinter in short time at low cost is considered to be more economical that the HIP method that requires complicated sintering conditions and high cost and the sintering can produce target materials in desired sizes and shapes to be used for thin film.

• 한국분말재료학회지
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• 제17권2호
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• pp.113-122
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• 2010

Two kinds of oxide-dispersion-strengthened (ODS) 316L stainless steel were manufactured using a wet mixing process(wet) and a mechanical alloying method (MA). An MA 316L ODS was prepared by a mixing of metal powder and a mechanical alloying process. A wet 316L ODS was manufactured by a wet mixing with 316L stainless steel powder. A solution of yttrium nitrate was dried after being in the wet 316L ODS alloy. The results showed that carbon and oxygen were effectively reduced during the degassing process before the hydroisostatic process (HIP) in both alloys. It appeared that the effect of HIP treatment on increase in impact energy was pronounced in the MA 316L ODS alloy. The MA 316L ODS alloy showed a higher yield strength and a smaller elongation, when compared to the wet 316L ODS alloy. This seemed to be attributed to the enhancement of bonding between oxide and matrix particles from HIP and to the presence of a finer oxide of about 20 nm from the MA process in the MA 316L ODS alloy.

• ETRI Journal
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• 제42권2호
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• pp.205-216
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• 2020

An arbiter physical unclonable function (APUF) has exponential challenge-response pairs and is easy to implement on field-programmable gate arrays (FPGAs). However, modeling attacks based on machine learning have become a serious threat to APUFs. Although the modeling-attack resistance of an MA-APUF has been improved considerably by architecture modifications, the response generation method of an MA-APUF results in low uniqueness. In this study, we demonstrate three design problems regarding the low uniqueness that APUF-based strong PUFs may exhibit, and we present several foundational principles to improve the uniqueness of APUF-based strong PUFs. In particular, an improved MA-APUF design is implemented in an FPGA and evaluated using a well-established experimental setup. Two types of evaluation metrics are used for evaluation and comparison. Furthermore, evolution strategies, logistic regression, and K-junta functions are used to evaluate the security of our design. The experiment results reveal that the uniqueness of our improved MA-APUF is 81.29% (compared with that of the MA-APUF, 13.12%), and the prediction rate is approximately 56% (compared with that of the MA-APUF (60%-80%).

• 대한안전경영과학회지
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• 제22권2호
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• pp.1-6
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• 2020

Apples are one of the most produced fruits in Korea, with 2,423,000 tons of fruits produced in Korea in 2018, of which 365,000 tons (MAF, 2018) account for about 15% of the total production. For quality safety after harvesting apples, the application of MA(modified atmosphere) packaging technology (Mostofi et. al., 2008) is being actively studied. In addition, the effects of functional packaging materials that have added functions such as fireproof, antibacterial, high-blocking, degradability, and far-infrared radiation have been studied (Chung et al., 2009). In addition, there are reports of the effects of quality changes (Park et al., 2007) and MA storage methods on the quality of apples by packing apples with functional MA films((Park et al., 2004). But there are only few reports on quality safety by analyzing the correlation between the change of reducing sugar and total sugar and preference during storage by packing Geochang, Yeongju, and Yesan apples in functional MA film. Therefore, this study aims to propose a method to secure the quality safety of apples by investigating the effect of sugar change on the preference of apples during storage by packing apples in three regions in functional MA films.

• Journal of Periodontal and Implant Science
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• 제53권5호
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• pp.321-335
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• 2023

Purpose: The aim of this study was to investigate the efficacy of photo-crosslinked gelatin methacryloyl (GelMa) hydrogel containing calcium phosphate nanoparticles (CNp) when applying different fabrication methods for bone regeneration. Methods: Four circular defects were created in the calvaria of 10 rabbits. Each defect was randomly allocated to the following study groups: 1) the sham control group, 2) the GelMa group (defect filled with crosslinked GelMa hydrogel), 3) the CNp-GelMa group (GelMa hydrogel crosslinked with nanoparticles), and 4) the CNp+GelMa group (crosslinked GelMa loaded with nanoparticles). At 2, 4, and 8 weeks, samples were harvested, and histological and micro-computed tomography analyses were performed. Results: Histomorphometric analysis showed that the CNp-GelMa and CNp+GelMa groups at 2 weeks had significantly greater total augmented areas than the control group (P<0.05). The greatest new bone area was observed in the CNp-GelMa group, but without statistical significance (P>0.05). Crosslinked GelMa hydrogel with nanoparticles exhibited good biocompatibility with a minimal inflammatory reaction. Conclusions: There was no difference in the efficacy of bone regeneration according to the synthesized method of photo-crosslinked GelMa hydrogel with nanoparticles. However, these materials could remain within a bone defect up to 2 weeks and showed good biocompatibility with little inflammatory response. Further improvement in mechanical properties and resistance to enzymatic degradation would be needed for the clinical application.

• Journal of Pharmaceutical Investigation
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• 제29권1호
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• pp.13-19
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• 1999

Canalicular liver plasma membrane vesicles (cLPM) were prepared according to two different methods (Inoue method and Meier method), and were evaluated for their protein yield, enzyme activity and transport characteristics. No difference was found between the methods in the protein yield (i.e., $0.14{\pm}0.031$ and $0.15{\pm}0.050$ mglg liver for Inoue method and Meier method, respectively). The activity of alkaline phosphatase, a marker enzyme of canalicular membrane, was significantly (P<0.05) higher in the vesicles of Meier method $(3.52{\pm}0.91\;mmol/mg/hr)$than in the vesicles of Inoue method ($2.28{\pm}0.94$ mmol/mg/hr) indicating that more purified cLPM were obtained from Meier method compared with Inoue method. ATP-dependent vesicular uptake of taurocholate and tributylmethylammonium (TBuMA) was observed for vesicles of both methods, and the kinetic parameters responsible for the transport were similar between the vesicles of both methods (for example, $V_{max}:$ 9.72 nmol/mg protein/30sec and $K_m:$ 0.63 mM for Inoue method; $V_{max}:$ 10.1 nmol/mg protein/30sec and $K_m:$ 0.70 mM for Meier method). A pH gradient dependent counter transport of TBuMA was also observed for both vesicles with similar kinetic characteristics. Either the uptake of taurocholate in the absence of ATP or that of TBuMA in the absence of pH gradient, which may represent passive diffusion of respective compound into the vesicles, was more rapid for the vesicles of Meier method than for the vesicles of Inoue method. For example, passive diffusion rate constants $(K_d)$ for TBuMA uptake into the vesicles were 0.00030 and 0.00052\;{\mu}l/mg$ protein/min for the vesicles of Inoue method and Meier method, respectively. It may indicate that more leaky vesicles are obtained form the Meier method compared with the Inoue method. These aspects together with the time necessary to prepare the vesicles (i.e., 8 hr for Inoue method and 23 hr for Meier method) should be considered before selecting an appropriate method for the preparation of cLPM.

• 한국군사과학기술학회지
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• 제14권3호
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• pp.327-334
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• 2011

It is necessary that UGV(Unmanned Ground Vehicle) should generate a real-time travesability index map by analyzing raw terrain information to travel autonomously tough terrain which has various slope and roughness values. In this paper, we propose a local path planning method, $MA^*$(Modified $A^*$) algorithm, using DVGM (Directional Velocity Grid Map) for unmanned ground vehicle. We also present a path optimization algorithm and a path smoothing algorithm which regenerate a pre-planned local path by $MA^*$ algorithm into the reasonable local path considering the mobility of UGV. Field test is conducted with UGV in order to verify the performance of local path planning method using DVGM. The local path planned by $MA^*$ is compared with the result of $A^*$ to verify the safety and optimality of proposed algorithm.