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This study analyzed and evaluated the energy performance and cost using electricity data from KEPCO (Korean Electric Power Corporation) and actual PV generate data. The analysis was conducted in two houses with different location and size. The demonstration houses were constructed with high thermal insulation and air tightness, and also designed as all-electric houses where all the energy supplies (including heating and cooking) are made of electricity which reduces the maintenance cost and makes maintenance easier. 6kWp grid connected photovoltaic system and air source heat pump for heating and hot water were applied to both houses. The result is summarized as follows. First, for two years, all energy (including plug load, heating, cooling, lighting, hot water supply and ventilation) was supplied by PV system and consequentially zero energy was achieved in both houses. Second, as a result of load matching analysis, in both houses, LCF in summer was relatively higher than that in other seasons and SCF in winter was relatively higher than that in other seasons. Third, monthly electricity bill by the amount of used were not charged, however, additional fees by domestic electricity charging system were charged such as basic electricity fee, VAT on receiving electricity and development fund; average $115 were paid per household.

A B S T R A C T K E Y W O R D Purpose: The window energy rating system was developed in early 1990's and various kind of rating system has been implemented in advanced country such as Europe, Australia, Canada and the US since 2000. In Korea, the Energy Consumption Efficiency Rating Indication System has been implemented to promote supply of high efficiency window since July 2012. Normally, the window energy rating system based on heat balance which considers both thermal losses and solar heat gain is used and applied only to residential buildings. However, the system used nationally only considers thermal losses and is applied to every building regardless of its usage. Therefore, in this study, we indicated problems of domestic window energy rating system and looked for improvements. Method: We analyzed thermal performance of various windows through dynamic simulation applied to detached house and compared results with those of domestic and foreign rating system. Result : Thermal performance of south windows is more affected by SHGC than U-value, and that of north windows is also affected by SHGC a lot. The difference between the results of our study and current system is statistically significant. As a result, appropriate evaluation criteria which considers solar heat gain is required. ⓒ 2016 KIEAE Journal 창호에너지평가시스템 열관류율 일사획득계수

Polymeric nanosphere-mediated gene delivery may sustain the duration of plasmid DNA (pDNA) administration. In this study, poly(lactic-co-glycolic acid) (PLGA) nanospheres were evaluated as a gene carrier. The pDNA-loaded PLGA nanospheres were formulated with high encapsulation efficiency (87%). The nanospheres sustained release of pDNA for 11 days. The released pDNA maintained its structural and functional integrity. Furthermore, the PLGA nanospheres showed lower cytotoxicity than polyethylenimine (PEI) in vitro and in vivo. The nanospheres with vascular endothelial growth factor (VEGF) gene were injected into skeletal muscle of ischemic limb model, and gene expression mediated by the PLGA nanospheres with VEGF gene was compared to that of PEI/pDNA or naked pDNA in vivo. PLGA nanosphere/pDNA had significantly higher VEGF expression levels in comparison to PEI/pDNA and naked pDNA at 12 days after administration. In addition, gene therapy using PLGA nanospheres resulted in more extensive neovascularization at ischemic sites than both naked pDNA and PEI/pDNA. These results indicated that PLGA nanosphere might be useful as a potential carrier for skeletal muscle gene delivery applications.

Combined angiogenic therapies may be superior to single angiogenic therapy for treatment of limb ischemia. First, we investigated whether the angiogenic efficacy of basic fibroblast growth factor (bFGF) administration and bone marrow-derived mononuclear cell (BMMNC) transplantation can be enhanced by sustained delivery (SD) of bFGF and BMMNC transplantation using a matrix, respectively, in mouse ischemic limbs. Next, we investigated whether the angiogenic efficacy of combination of two angiogenic strategies is superior to either strategy alone. One day after surgical induction of mouse hindlimb ischemia, mice were randomized to receive either no treatment, daily injection (DI) of bFGF, SD of bFGF, BMMNC transplantation using culture medium, BMMNC transplantation using fibrin matrix (FM), or combination of SD of bFGF with BMMNC transplantation using FM. The SD of bFGF significantly increased the microvessel density, compared with DI of bFGF (659±48/mm2 versus 522±39/mm2, p 0.05 ). BMMNC transplantation using FM significantly increased the microvessel density, compared with BMMNC transplantation using culture medium (523±103/mm2 versus 415±75/mm2, p 0.05 ). Importantly, combination of bFGF sustained release with BMMNC transplantation using FM further increased the densities of microvessels and arterioles, compared to either strategy alone ( p 0.05 ). The SD method of angiogenic protein and cell transplantation using matrix potentiate the angiogenic efficacy of bFGF and BMMNC transplantation, respectively, for limb ischemia. In addition, the combined therapy of SD of bFGF and BMMNC transplantation synergistically enhances angiogenesis in mouse ischemic limb, compared to each separate therapy.

Controlled long-term delivery of basic fibroblast growth factor (bFGF) could be used as an angiogenesis therapy. In this study, novel heparin-conjugated poly(L-lactide-co-glycolide) (PLGA) nanospheres (HCPNs) were developed for long-term, zero-order delivery of bFGF. HCPNs were prepared by using a coupling reaction between amino-terminated PLGA nanospheres and heparin in the presence of 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide. The amount of heparin conjugated to the PLGA nanospheres was increased up to 29-fold by using nanospheres made from lower molecular weight PLGA, or star-shaped PLGA, as compared to nanospheres made from higher molecular weight PLGA, or linear PLGA. The release of bFGF from HCPNs was sustained for 3 weeks with no initial burst release. The bFGF release period was increased to more than 4 weeks using a delivery system of HCPNs suspended in fibrin gel. The release was nearly zero order. The rate of bFGF release from HCPNs in fibrin gel was controlled by the fibrinogen concentration in the fibrin gel. As the fibrinogen concentration increased, the bFGF release rate decreased. The bioactivity of bFGF released from HCPNs in fibrin gel was assessed using human umbilical vein endothelial cell (HUVEC) culture. bFGF released from HCPNs in fibrin gel exhibited HUVEC growth for 15 days, similar to that of cultures to which bFGF in free form was added daily, suggesting that the delivery system of HCPNs in fibrin gel can release bFGF in a bioactive form for a long period. The therapeutic potential of bFGF delivery using HCPNs in fibrin gel was investigated in a mouse limb ischemia model. Immunohistological analysis of mouse ischemic limbs indicated that the microvessel density was much higher in the ischemic limbs treated with bFGF delivery using HCPNs in fibrin gel than in the ischemic limbs treated with daily injections of bFGF or with bFGF delivery using fibrin gel. This study shows that a bFGF delivery system using HCPNs in fibrin gel exhibits controllable, long-term, zero-order release of bFGF and potentiates the angiogenic efficacy of bFGF administration.

Polymeric nanospheres fabricated from biodegradable poly(lactide-co-glycolide) (PLGA) have been extensively investigated for applications in gene delivery. In this study, we show that the covalent conjugation of a nuclear localization signal (NLS, SV40 peptide) on PLGA nanospheres enhances the gene transfection efficiency. NLS conjugated PLGA copolymer was prepared by using a coupling reaction between maleimide-terminated PLGA copolymer and NLS in the presence of Imject maleimide conjugation buffer. PLGA nanospheres encapsulating plasmid (pDNA) were prepared by using a double emulsion-solvent evaporation method. The kinetics of in vitro release of pDNA from PLGA nanospheres was determined with UV in phosphate buffered saline (PBS). Gene transfection efficiency in human dermal fibroblasts was tested in vitro using nanospheres encapsulating the luciferase gene. The conjugation of the NLS peptide to the PLGA nanospheres could improve the nuclear localization and/or cellular uptake of PLGA nanosphere/pDNA constructs and thereby improve the transfection efficiency of a PLGA nanosphere gene delivery system. The pDNA was released from PLGA nanospheres over nine days. NLS conjugation enhanced the gene transfection efficiency in vitro by 1.2 approximately 3.2-fold over 13 days. PLGA/pDNA nanospheres appeared to be superior to PEI/pDNA complexes for the long-term expression of pDNA. Furthermore, the level of the sustained gene expression of the PLGA nanospheres was enhanced by the conjugation of NLS to the PLGA nanospheres. This study showed that the NLS conjugation enhanced the gene transfection efficiency of the PLGA nanosphere gene delivery system in vitro and that the enhanced gene expression was sustained for at least 13 days.