• 한국방사선학회논문지
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• 제13권2호
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• pp.241-246
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• 2019

4차 산업혁명의 기술 중 3D 프린팅 기술의 소재에 따른 선량평가를 통해 볼루스 적용 가능성을 평가하였다. 선량의 평가는 몬테카를로 방식의 MCNPX프로그램을 이용하였으며, 3D 프린트 물성은 ABS, PC, PLA 세 가지로 하였다. 그리하여 볼루스 10 mm와 동일한 효과를 보이는 두께를 산정한 결과 6 MeV 전자선의 경우 ABS 10 mm, PC 9 mm, PLA 9 mm로 나타났다. 6 MV X-선의 경우 ABS 11 mm, PC 10 mm, PLA 9 mm로 나타났다. 본 실험을 통해 3D 프린터 소재로 제작하는 조직등가물질이 볼루스를 대체할 수 있음을 확인할 수 있었다.

• 대한전자공학회논문지
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• 제23권5호
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• pp.666-673
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• 1986

본 논문에서는 다중고장 검출이 가능하고 부가회로가 적은 새로운 PLA 설계방식을 제안하였다. 부가회로로는 하나의 쉬프트레지스터 열과 2 비트 디코우터에 제어입력을 사용하였다. 제어입력을 사용하므로써 비트선들을 효과적으로 제어할 수 있다. 종래의 논문들에서 구체적으로 다루지 않았던 단락고장과 서로 다른 모델 간의 다중고장을 다루었으며 고장의 등가관계 및 지배고장(Dominant Faults)을 정의하여 다중고장을 해석하였다. 또한 본 설계방식을 Folded PLA에도 적용하였다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권5호
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• pp.2967-2971
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• 2013

Background: Extraskeletal Ewing sarcoma (EES)/primitive neuroectodermal tumours (PNET) are rare soft tissue sarcomas. Prognostic factors and optimal therapy are still unconfirmed. Materials and Methods: We performed a retrospective analysis on patients to explore the clinic characteristics and prognostic factors of this rare disease. A total of 37 patients older than 15 years referred to our institute from Jan., 2002 to Jan., 2012 were reviewed. The characteristics, treatment and outcome were collected and analyzed. Results: The median age was 28 years (range 15-65); the median size of primary tumours was 8.2 cm (range 2-19). Sixteen patients (43%) had metastatic disease at the initial presentation. Wide surgical margins were achieved in 14 cases (38%). Anthracycline or platinum-based chemotherapy was performed on 29 patients (74%). Radiotherapy was delivered in 13 (35%). At a median follow-up visit of 24 months (range 2-81), the media event-free survival (EFS) and overall survival (OS) were 15.8 and 30.2 months, respectively. The 3-year EFS and OS rates were 24% and 43%, respectively. Metastases at presentation and wide surgical margins were significantly associated with OS and EFS. Tumour size was significantly associated with OS but not EFS. There were no significant differences between anthracycline and platinum based chemotherapy regarding EFS and OS. Conclusions: EES/PNET is a malignant tumour with high recurrence and frequent distant metastasis. Multimodality therapy featuring wide surgical margins, aggressive chemotherapy and adjuvant local radiotherapy is necessary for this rare disease. Platinum-based chemotherapy can be used as an adjuvant therapy.

• 펄프종이기술
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• 제44권6호
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• pp.28-35
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• 2012

Water-in-oil emulsion (W/O) and oil-in-water emulsion (O/W) types biodegradable polymer emulsions prepared to PLA and PBS. The optimal mixing ratio of polymer : solvent : OA : TEA : water was found be 10 : 40 : 4 : 6 : 30(g) when preparing emulsions. Biodegradability was most retained after preparation of polymer emulsions. Particle size of PLA and PBS emulsions were 2-3 ${\mu}m$ and 3-4 ${\mu}m$, respectively. Molecular weight of PLA and PBS emulsions were 108,000 and 92,000, respectively. And molecular weight of PLA and PBS emulsions became slightly lower than those of pellets.

• Journal of the Korean Wood Science and Technology
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• 제37권5호
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• pp.426-433
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• 2009

This study investigates the tensile and morphological properties of nanocomposites prepared from poly(lactic acid) (PLA), wood flour (WF) and montmorillonite (MMT) by melt compounding with a twin screw extruder. In order to enhance the mechanical properties of PLA/WF composites, maleic anhydride grafted PLA (MAPLA) is synthesized as a compatibilizer. MAPLA prepared in the laboratory is characterized using FT-IR (Fourier transformed infrared spectroscopy). From the results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis for nanocomposites, we confirmed that silicate layers of MMT are intercalated and partially exfoliated. When 2 wt% MAPLA is added, the tensile strength and modulus of PLA/WF/MAPLA composites were higher than those of the PLA/WF composite. The addition of MMT increases the tensile modulus of PLA/WF/MAPLA composites but decreases the tensile strength.

• Composites Research
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• 제35권6호
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• pp.419-424
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• 2022

Using non-biodegradable polymers is a severe environmental problem as they are not recyclable and generate a large amount of waste. Biopolymers, such as starch-based composites, have been considered one of the most promising replacement materials. These eco-friendly materials have the advantage of being low-cost, biodegradable, and obtained from renewable sources. However, as starch tends to be brittle and hydrophilic, it can make these materials unusable when exposed to water and limit its processability for further applications. In this work, a biobased modified starch was grafted using two bioderived materials, lauryl methacrylate (LMA) and tetrahydrofurfuryl methacrylate (THFMA), by radical polymerization. A polylactic acid (PLA) composite based on the modified starch (m-St) was fabricated to enhance its toughness. These samples were characterized by Fourier transform infrared, ¹H NMR and ¹³C NMR analysis, optical and scanning electron microscopy. The starch was successfully grafted, thus improving the compatibility with the PLA matrix. The mechanical properties of these films were also studied. Results from mechanical tests showed a slight enhancement of the mechanical performance of these composites when m-St was added to the PLA matrix. Such behavior is related to the improved dispersion of m-St 1:2 on PLA, confirmed by SEM images showing enhanced compatibility between modified starch and PLA matrix. This indicated excellent properties of the produced composite film for further eco-friendly applications.

• 공업화학
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• 제26권3호
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• pp.251-258
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• 2015

본 연구에서는 L-lactide를 이용하여 수평균분자량(Mn)과 중량평균분자량($M_w$)이 각각 12,000, 14,000 g/mol인 PLLA (Poly L-lactic acid) 수지를 합성하였으며, 이 PLLA를 이용하여 PLLA-Br 중간체를 합성하였다. PLLA-Br 중간체를 이용하여 수평균분자량($M_n$)과 중량평균분자량($M_w$)이 각각 84,000, 126,000 g/mol인 PLLA-block-PMMA (Poly L-lactic acid-block-Polymethyl methacrylate) 공중합체를 최종적으로 합성하였으며 PLLA-block-PMMA 공중합체의 유리전이온도($T_g$)는 $95.5^{\circ}C$, 열분해 개시온도는 $289^{\circ}C$이었다. PLA에 PLLA-block-PMMA를 9 phr 혼용하고 $95^{\circ}C$에서 3배 이축연신한 다음 $120^{\circ}C$에서 2 min 동안 저온열처리하여 두께가 $50{\pm}3{\mu}m$인 PLA 필름을 제조하였다. 550 nm 파장에서 측정한 PLA 필름의 빛투과율은 88.5%, 인장강도는 44.5 MPa이었으며 PLA 필름의 인장강도를 현 수준보다 개선하기 위해서는 이축연신후 $120^{\circ}C$의 온도조건에서 2 min보다 긴 저온열처리시간이 필요하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.3789-3809
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• 2015

In this paper, we deal with the problem of M2M gateways' network selection for different types of M2M traffic in heterogeneous wireless networks. Based on the difference in traffic's quality of service (QoS) requirements, the M2M traffic produced by various applications is mainly classified as two categories: flexible traffic and rigid traffic. Then, game theory is adopted to solve the problem of network-channel selection with the coexistence of flexible and rigid traffic, named as flexible network access (FNA). We prove the formulated discrete game is a potential game. The existence and feasibility of the Nash equilibrium (NE) of the proposed game are also analyzed. Then, an iterative algorithm based on optimal reaction criterion and a distributed algorithm with limited feedback based on learning automata are presented to obtain the NE of the proposed game. In simulations, the proposed iterative algorithm can achieve a near optimal sum utility of whole network with low complexity compared to the exhaustive search. In addition, the simulation results show that our proposed algorithms outperform existing methods in terms of sum utility and load balance.

• 생명과학회지
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• 제29권5호
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• pp.514-523
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• 2019

인삼(Panax ginseng C. A. Meyer)의 사포닌 진세노사이드 Rb1이 처리된 인간 피부각질세포 HaCaT에서 microarray 분석 및 발현이 증가된 세포사멸 반응에 대한 작용기전을 연구하였다. HaCaT 세포에 진세노사이드 Rb1의 처리로 세포사멸, 유사분열 세포주기의 G2/M 전이, 세포분열, 핵분열, 그리고 단백질 수송 등의 작용기전에 관여하는 유전자들이 2 배 이상 발현이 증가된 것으로 나타났으며, DNA 수선, 감수 핵분열, 그리고 세포외기질 체계 등의 작용기전에 관여하는 유전자들은 2 배 이상 발현이 감소된 것으로 나타났다. 특히 세포사멸 신호전달은 FAS와 PLA2G4A를 경유하는 것으로 나타났으며, 이들 유전자의 상위 조절자로 STAT3가 예측되었다. 세포사멸 반응 경유 유전자 FAS와 PLA2G4A의 활성을 qPCR로 확인한 결과, FAS 유전자는 $10{\mu}g/ml$의 진세노사이드 Rb1를 24시간 동안 처리하였을 경우 약 2 배의 발현 증가와, PLA2G4A 유전자는 6시간 처리부터 약 2 배로 증가되어 24시간 동안 처리시 2 배 이상의 유전자 발현이 증가되었다. 한편 STAT3-siRNA를 이용한 knock-down 실험에서 FAS의 발현 감소와 PLA2G4A의 발현 증가로 상위 조절자 STAT3로부터 FAS 만을 경유하는 것을 알 수 있었다. 이상의 결과 진세노사이드 Rb1의 처리에 의해 상위 조절자인 STAT3는 FAS를 경유하여 세포사멸을 유도하는 것임을 알 수 있다.

• BMB Reports
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• 제31권2호
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• pp.189-195
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• 1998

Methylmercury (MeHg), which is widely distributed in the environment, is well known for both its acute and chronic poisoning effects on the human health; however, the precise biochemical mechanisms by which this compound elicits its toxicity in a cellular level are still poorly understood. To examine whether MeHg-induced liver injury involves activation of Phospholipase $A_2$ ($PLA_2$), the $PLA_2$ activity of control and MeHg-administrated livers was measured. MeHg stably enhanced a liver form of cytosolic $PLA_2$ activity, which exhibited several biochemical properties similar to those of the 100 kDa $cPLA_2$, except in its elution profile of a DEAE-5PW HPLC, and it migrated as a molecular weight of 80 kDa in Western blot analysis. This blotting analysis also indicated that the MeHg-induced enhancement of the activity could be due to the increase in the amount of the enzyme protein rather than a stable modification of the enzyme such as phosphorylation. Our data also showed the higher myeloperoxidase activity in MeHg-administrated liver than in the control, suggesting that this increase in the amounts of the 80 kDa $PLA_2$ and its activity may be resulted from infiltration of neutrophils into the liver during a hepatic injury process such as MeHg-induced inflammation. Taken together, these data suggest that MeHg-induced liver injury may be mediated by activation of the 80 kDa form of liver cytosolic $PLA_2$.