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PARP inhibitors have been approved by the FDA for use in the treatment of patients with ovarian, breast, pancreatic, and prostate cancers. PARP inhibitors show diverse suppressive effects on PARP family members and PARP-DNA trapping potency. These properties are associated with distinct safety/efficacy profiles. Here, we report the nonclinical characteristics of venadaparib (also known as IDX-1197 or NOV140101), a novel potent PARP inhibitor. The physiochemical properties of venadaparib were analyzed. Furthermore, the efficacy of venadaparib against PARP enzymes, PAR formation, and PARP trapping activities, and growth inhibition of cell lines with BRCA mutations were evaluated. Ex vivo and in vivo models were also established to study pharmacokinetics/pharmacodynamics, efficacy, and toxicity. Venadaparib specifically inhibits PARP-1 and -2 enzymes. Oral administration of venadaparib HCl at doses above 12.5 mg/kg significantly reduced tumor growth in the OV_065 patient-derived xenograft model. Intratumoral PARP inhibition remained at over 90% until 24 hours after dosing. Venadaparib had wider safety margins than olaparib. Notably, venadaparib showed favorable physicochemical properties and superior anticancer effects in homologous recombination-deficient in vitro and in vivo models with improved safety profiles. Our results suggest the possibility of venadaparib as a next-generation PARP inhibitor. On the basis of these findings, phase Ib/IIa studies on the efficacy and safety of venadaparib have been initiated.

Supplementary Table 1, Supplementary Table 2, Supplementary Figure 1

Venadaparib (VEN), a next-generation inhibitor of poly (ADP-ribose) polymerases, is under development for oral use in patients having cancers with deoxyribonucleic acid repair defects. The objective of this study was to develop and validate a sensitive and robust analytical method for quantifying VEN in a small volume of plasma samples from rats and dogs, and to assess the feasibility of the assay for application in pharmacokinetic/toxicokinetic studies. Plasma samples were subjected to deproteination, and an aliquot was injected into an LC–MS/MS system. VEN and imipramine were analyzed in the positive ion mode and quantified by monitoring the transition at m/z 407.2 → 70.0 for VEN and 281.2 → 86.1 for imipramine. The lower and upper limits of the assay were determined to be 1 and 1000 ng/mL, respectively, with acceptable linearity (r2 > 0.995). Validation parameters, such as accuracy, precision, dilution, recovery, matrix effect, and stability, were within acceptable ranges. This method was adequately applied to the characterization of pharmacokinetics of VEN in rats and dogs at the oral dose of 30 and 0.5 mg/kg, respectively. These findings suggest that the validated assay is applicable to the kinetic studies of VEN with a small volume of plasma samples from the animals.

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The dissimilar materials of pipe component was produced between A105 forged steel and A312 stainless steel. In order to determine the superiority of the friction-welded component, its thermomechanical behavior was studied. In situ observations and finite elemental analysis recorded the difference in the thermal distribution of the pipe components. The high-speed camera observations revealed a large amount of material flow in stainless steel during welding. The temperature and amount of material flow increased with the increase in heating time. The finite elemental modeling exhibited the presence of maximum temperature at the periphery of the joint. The distribution of heat flow on stainless steel was uniform, while it slowly increased from periphery to the center of the joint for forged steel. The required amount of temperature was obtained at a heating time of 6 s and distributed evenly throughout the joint. Finite elemental modeling and experimental analysis confirmed the growth of temperature at the joint interface as heating time increased.

This study was carried out to investigate the creep life at the high temperature of the Alloy 718 for automotive engine components using the initial strain parameter method (ISPM). Creep tests have performed at elevated temperatures in the range of 550 oC to 700 oC in this work. We also carried out constant stress creep tests. The initial strains were measured during 1 minute after loading. Both the creep stress and rupture time depend on the initial strain. We calculated the creep life of Alloy 718 by using the creep life prediction equations obtained from the ISPM. Then, we compared the creep life predicted by the ISPM to the Larson-Miller parameter (LMP). The experimental rupture time and the calculated rupture time by using the ISPM agreed with a confidence level of 95 %. The creep life predicted by using the ISPM was in very good agreement with the creep life predicted using the LMP method.

A reference-based adaptive resistance spot welding (RSW) method intended to reduce the shunting effect in short-pitch (≤40 mm) RSW is proposed in this study. As the weld pitch decreases, the nugget diameter and dynamic resistance level concurrently decrease by an amount equivalent to the increased shunting effect. Based on this fundamental relationship, an exponential model capable of predicting weld pitch as a function of dynamic resistance was estimated. Next, the relationship between the nugget diameter and the heat input as a function of weld pitch was investigated, and a logistic growth model capable of predicting heat input compensation was established. These exponential and logistic growth models form the basis of the proposed RSW method’s control algorithm. The proposed RSW method compensates for the heat input loss caused by the shunting effect by adjusting welding time in real time under a constant current control until the predicted heat input compensation is obtained. Experimental results indicated that the RSW method proposed in this study concurrently increased the nugget diameter and decreased the shunting effect in short-pitch RSW compared with conventional welding method results. This finding suggests that the proposed reference-based adaptive RSW method is effective in reducing the shunting effect in short-pitch RSW.

Welds on fuel rods necessary for nuclear power generation have the highest possibility of leaking during combustion, and accordingly these welds must have integrity and strength. Welding methods of nuclear fuel rods commonly used by nuclear fuel manufacturers include GTAW, EBW, LBW, resistance upset butt welding, etc. In Korea, the resistance upset butt welding method is used. While the weld integrity is evaluated by fracture tests, there is a lack of understanding regarding the weld mechanism during the welding process. In this study, a coupled axisymmetric finite element model (FEM) was formulated to simulate the resistance upset butt welding process between the end plug and cladding tube by a numerical simulation. By simulating this process, the electrode displacement, dynamic temperature curves, melted volume, and resistance of the welding area were studied by changing weld parameters and validated through comparison with experimental results. Finally, in order to improve the integrity of weldment of the fuel rods in nuclear power plants, an estimation equation by regression model for optimal welding conditions was derived.

Background Cancer is a complex disease with profound genomic alterations and extensive heterogeneity. Recent studies on large-scale genomics have shed light on the impact of core oncogenic pathways, which are frequently dysregulated in a wide spectrum of cancer types. Aberrant activation of the hepatocyte growth factor (HGF) signaling axis has been associated with promoting various oncogenic programs during tumor initiation, progression, and treatment resistance. As a result, HGF-targeted therapy has emerged as an attractive therapeutic approach. However, recent clinical trials involving HGF-targeted therapies have demonstrated rather disappointing results. Thus, an alternative, in-depth assessment of new patient stratification is necessary to shift the current clinical course. Methods To address such challenges, we have evaluated the therapeutic efficacy of YYB-101, an HGF-neutralizing antibody, in a series of primary glioblastoma stem cells (GSCs) both in vitro and in vivo. Furthermore, we performed genome and transcriptome analysis to determine genetic and molecular traits that exhibit therapeutic susceptibility to HGF-mediated therapy. Results We have identified several differentially expressed genes, including MET, KDR, and SOX3, which are associated with tumor invasiveness, malignancy, and unfavorable prognosis in glioblastoma patients. We also demonstrated the HGF-MET signaling axis as a key molecular determinant in GSC invasion, and we discovered that a significant association in HGF expression existed between mesenchymal phenotype and immune cell recruitment. Conclusions Upregulation of MET and mesenchymal cellular state are essential in generating HGF-mediated therapeutic responses. Our results provide an important framework for evaluating HGF-targeted therapy in future clinical settings.

Resistance nut projection weldability of Al–Si coated hot stamped steel (HSS) was investigated under the viewpoint of weldable current range and joint strength (pull-out load). The microstructural inhomogeneities in the welds were also studied in order to elucidate the factors affecting the joint strength of the welds. The weldability of the given Al–Si coated HSS was compared with the weldability of an identical HSS without the Al–Si coating (Al–Si coating was polished out) and Zn coated dual phase steel. The weldable current range of Al–Si coated HSS was found to be narrower than that of the other materials. Furthermore, the average pull-out load within the weldable current range of the Al–Si coated HSS was the lowest among the three materials. The reason for poor weld mechanical property of the Al–Si coated hot-stamped steel was attributed to the microstructural inhomogeneities such as unmixed Al–Si coating layer at the edge of the nugget and the second phase Fe3(Al, Si) intermetallic compound. The formation of Fe3(Al, Si) phase was attributed to the solidification segregation of Al and Si during the weld solidification and was confirmed with the numerical analysis of solidification segregation.

Injection molding process is widely used for producing most plastic products. In order to make a metal-colored plastic product especially in modern luxury home alliances, metallic pigments which are mixed to a basic resin material for injection molding are available. However, the process control for the metal-colored plastic product is extremely difficult due to non-uniform melt flow of the metallic resin pigments. To improve the process efficiency, a rapid mold cooling method by a compressed cryogenic fluid and electricity mold are also proposed to decrease undesired compound contents within a molded plastic product. In this study, a quality of the metal-colored plastic product is evaluated with process parameters; injection speed, injection pressure, and pigment contents, and an influence of the rapid cooling and heating system is demonstrated.

Lightweight metals have been used to manufacture the body panels of cars to reduce the weight of car bodies. Typically, aluminum sheets are welded together, with a focus on weld quality assurance. A weld quality prediction system for the laser welding of aluminum was developed in this research to maximize welding production. The behavior of the plasma was also analyzed, dependent on various welding conditions. The light intensity of the plasma was altered with heat input and wire feed rate conditions, and the strength of the weld and sensor signals correlated closely for this heat input condition. Using these characteristics, a new algorithm and program were developed to evaluate the weld quality. The design involves a combinatory algorithm using a neural network model for the prediction of tensile strength from measured signals and a fuzzy multi-feature pattern recognition algorithm for the weld quality classification to improve predictability of the system.

Buoy is the structure which is floated on sea surface in order to indicate the presenting obstacle such as reef and shallow sea and to show the direction of sea route to ship during sailing. Generally, the conventional material of buoy is steel and it has some problems. Firstly this steel light buoy has safety risk in case of collision between ship and steel buoy. Secondly steel buoy revealed high corrosion environment of salted water and oxide and corrosion of steel can lead to marine pollution. Thirdly it needs too much maintain cost because of its heavy weight. In this study, in order to overcome these problems we changed the buoy material from conventional steel body to polyethylene body. Polymer buoy body was designed with module type part and it can reduce total weight up to 43.12%. To evaluate the strength of that part, the structure analysis simulation was carried out with respect to stress, displacement, and strain. Maximum stress was 1.667 × 107 N/m2 and it was 25% of yielding stress of base material. Maximum displacement and strain were 3.164 mm and 0.00433353 and they are too small value and in safe range with comparing to total length of body. The stability of polymer buoy body was compared with conventional buoy with respect to center of gravity, center of buoyancy, metacenter, oscillation period, and tilt angle by wind, tidal current, and wave. Every value was improved comparing conventional one and we can get more stable buoy. Therefore the new polymer buoy body could prove its safety and stability.

Background: YYB101, a humanized monoclonal antibody against hepatocyte growth factor (HGF), has shown safety and efficacy in vitro and in vivo. This is a first-in-human trial of this antibody. Materials and Methods: YYB101 was administered intravenously to refractory cancer patients once every 4 weeks for 1 month, and then once every 2 weeks until disease progression or intolerable toxicity, at doses of 0.3, 1, 3, 5, 10, 20, 30 mg/kg, according to a 3+3 dose escalation design. Maximum tolerated dose, safety, pharmacokinetics, and pharmacodynamics were studied. HGF, MET, PD-L1, and ERK expression was evaluated for 9 of 17 patients of the expansion cohort (20 mg/kg). Results: In 39 patients enrolled, no dose-limiting toxicity was observed at 0.3 mg/kg, and the most commonly detected toxicity was generalized edema ( n = 7, 18.9%) followed by pruritis and nausea ( n = 5, 13.5%, each), fatigue, anemia, and decreased appetite ( n = 4, 10.8%, each). No patient discontinued treatment because of adverse events. YYB101 showed dose-proportional pharmacokinetics up to 30 mg/kg. Partial response in 1 (2.5%) and stable disease in 17 (43.5%) were observed. HGF, MET, PD-L1, and ERK proteins were not significant predictors for treatment response. However, serum HGF level was significantly lowered in responders upon drug administration. RNA sequencing revealed a mesenchymal signature in two long-term responders. Conclusion: YYB101 showed favorable safety and efficacy in patients with refractory solid tumors. Based on this phase I trial, a phase II study on the YYB101 + irinotecan combination in refractory metastatic colorectal cancer patients is planned. Conclusion: ClinicalTrials.gov Identifier: NCT02499224

Microstructural evolution and failure characteristics/mechanisms were investigated for thermal barrier coatings that consist of electron beam physical vapor deposited ZrO2−8 wt% Y2O3 (YSZ) topcoat, Pt-modified nickel aluminide, (Ni,Pt)Al bond coat, and CMSX-4 superalloy substrate with furnace cycling at 1100 °C with 1-h dwell. Photo stimulated luminescence spectroscopy, scanning electron microscopy equipped with X-ray energy dispersive spectroscopy and transmission electron microscopy were employed to examine the residual stress of the thermally grown oxide (TGO) and microstructural changes. For comparison, (Ni,Pt)Al bond coat on CMSX-4 without the YSZ topcoat was also characterized. The TGO grew faster for the YSZ-coated (Ni,Pt)Al bond coat than the (Ni,Pt)Al coating without the YSZ topcoat. Correspondingly, the β-to-γ′/martensite formation in the (Ni,Pt)Al bond coat occurred faster on the YSZ-coated (Ni,Pt)Al bond coat. However the rumpling occurred much faster and with larger amplitude on the (Ni,Pt)Al coating without the YSZ topcoat. Still, the rumpling at the TGO/bond coat interface caused crack initiation as early as 10 thermal cycles, decohesion at the YSZ/TGO interface, and eventual spallation failure primarily through the TGO/bond coat interface. The magnitude of compressive residual stress in the TGO showed an initial increase up to 3−4 GPa followed by a gradual decrease. The rate of stress relaxation was much quicker for the TGO scale without the YSZ topcoat with distinctive relief corresponding to the cracking at the top of geometrical ridges associated with the (Ni,Pt)Al bond coat. The maximum elastic energy for the TGO scale was estimated at 90 J/m2 at 50% of its lifetime (Nf=545 cycles). The YSZ presence/adhesion to the TGO scale is emphasized to minimize the undulation of the TGO/bond coat interface, i.e., decohesion at the YSZ/TGO scale accelerates the rumpling and crack-coalescence at the TGO/bond coat interface where the spallation fracture occurs.

Nowadays, car manufacturers applied many high strength steels such AHSS or UHSS to car bodies for weight lightening. Therefore, a variety of applied steel sheet to car bodies increased and the needs of simulation to evaluate weldability also increased in order to reduce the cost and time. In this study, resistance spot welding simulations for DP 780 Steel with 1.0 and 1.4 mm thickness were conducted with respect to lobe curve. 2 regression models to estimate tensile shear strength were suggested and they were second order polynomial regression model and optimized second order regression model. The performance of these models was evaluated in terms of the coefficient of determinant and average error rate. Key Words ：Resistance spot welding, Simulation, Lobe Curve, Regression Model **†박영환(교신저자) : 국립부경대학교 기계공학과E-mail : parkyw@pknu.ac.kr, Tel : 051-629-6148 *손창석 : 국립부경대학교 기계공학과**†Young-Whan Park(corresponding author) : Department of Mechanical Engineering, Pukyong National University.E-mail : parkyw@pknu.ac.kr, Tel : 051-629-6148 *Chang-Seok Son : Department of Mechanical Engineering, Pukyong National University.

* 부산대학교 융합학부 ** 부산대학교 재료공학과 *** 대우조선해양 산업기술 연구소 **** 부경대학교 기계공학과 Abstract The effect of welding condition on microstructure and mechanical property of Plasma-MIG Hybrid Weld between Al 5083 plates(thickness : 10mm) was investigated. 1 pass weld without any defects such as puckering, undercut, and lack of fusion was obtained by 150~200A of plasma current and 5~7mm of welding speed. Gas porosities and shrinkage porosities were existed in the weld near fusion line. As welding speed and plasma current were decreasing, the area fraction of porosity was increasing. The hardness of the weld is increasing as welding speed. On the basis of microstructural analysis, Mg segregated region near dendrite boundaries tends to increase with the welding speed. In the result of hardness test, Distribution of hardness in fusion zone showed little change with the plasma current. However, when the welding speed increased, hardness in weld metal markdly increased. It could be considered that effect of heat input to growth of the dendritic solidification structures. Based on tensile test, tensile properties of weld metal was predominated by area fraction of porosities. Consequently, tensile properties can be controlled by formation site and area fraction of porosity.

{( y j : 2013 2 08  14 j , j : 2014 2 02  13 j , $2(E.C : 2014 2 03  04 j ){Abstract: Friction welding is a very useful joining process to weld metals which have axially symmetric cross section. In this paper, for the friction welding with tube-to-tube shape, the feasibility of industry application was determined using analyzing mechanical properties of weld and optimized welding variables was suggested. In order to accomplish this object, rotating speed, friction heating pressure, and friction heating time were selected as the major process variables and the experiment was performed in three levels of each parameter. Weld characteristic was investigated in terms of weld shape and metal loss, and 7mm of metal loss was regarded as the optimal metal loss. By tensile test, tensile strength and yielding strength was measured and fracture was occurred at base metal. In order to optimize the welding condition, fitness function was defined with respect to metal loss and yielding strength and the fitness values for each welding condition could be calculated in experimental range. Consequently, we set the optimal welding condition as the point which had maximum value of fitness function. As the result of this paper the optimal welding variables could be suggested as rotating speed was 1300 rpm, friction heating pressure was 15 MPa, and friction heating time was 10 sec. Key Words ™ Friction Welding, Metal Loss, Mechanical Property, Fitness Function, Process Variable Optimization

In this paper, I-butt welding with 6mm thickness using Plasma-GMA welding was carried out. And weld characteristics of the Al-5083 aluminium alloy for Plasma-GMA hybrid welding was evaluated. The orthogonal experimental design was used to investigate the influence of plasma-MIG welding parameters such as plasma current, wire feeding rate, MIG-welding voltage and welding speed on the weld bead geometry and tensile strength using the ANOVA(Analysis of Variation). Then we conducted evaluation of contribution for process parameters. ANOVA results show that bead dimensions are affected by wire feeding speed, welding voltage and welding speed and tensile strength is mainly affected by welding speed and plasma arc current. Tensile strength was decreased by rise in plasma welding current because GMA welding current was decreased by plasma arc.Key Words : AL5083 alloy, Plasma-GMA welding, ANOVA, Hybrid welding, Orthogonal design ISSN 1225-6153Online ISSN 2287-8955 1. 서 론 최근 세계적으로 해양환경 오염규제 및 에너지 절감 등에 대한 요구가 높아짐에 따라 중소형선의 경우 경량화, 높은 내식성, 재활용이 가능한 환경 친화적인 선박에 대한 수요가 증가하고 있다. 특히 중소형 선박에 사용되어 왔던 FRP(fiber reinforced plastic) 소재는 생산비용이 낮은 장점은 있으나, 폐선처리가 문제가 되면서 알루미늄 선박에 관심이 고조되고 있다

β-Lactamase inhibitors with a bicyclic urea core and a variety of heterocyclic side chains were prepared and evaluated as potential partners for combination with imipenem to overcome class A and C β-lactamase mediated antibiotic resistance. The piperidine analog 3 (MK-7655) inhibited both class A and C β-lactamases in vitro. It effectively restored imipenem's activity against imipenem-resistant Pseudomonas and Klebsiella strains at clinically achievable concentrations. A combination of MK-7655 and Primaxin® is currently in phase II clinical trials for the treatment of Gram-negative bacterial infections.

The wire feeding system for gas metal arc welding usually consists of a wire feeder and a torch. In many industries, the distance between the wire feeder and the torch is generally 3 m to 5 m. In a conventional wire feeder, a direct current (DC) motor is used for wire feeding. However, a significant problem with this system is the impossibility of feedback control because of inner or outer impedance. In this paper, a digital wire feeder was developed by using a DC encoder motor and a push-pull torch. An optimized wire-feeding system was also developed by experiment. The welding process was observed using a high-speed camera. The resulting wire-feeding system exhibits low spatter generation and arc stability.

Nowadays, car manufacturers tried to improve automotive fuel efficiency, and applied many high strength steels such as AHSS or UHSS to car bodies. Therefore, the number of steel combinations for the resistancespot welding are dramatically increased and the need for weldability evaluation of these combinations are also required. In this study, we suggest the lobe curve using FEM simulations for DP780 steel with 1.0t, 1.4t. The lobe curves which could expressed weldablity and optimal welding condition were obtained according to 6 steel combinations. There were two combinations for same steel sheet which were DP780 1.0t, DP780 1.4t. Dissimilar steel sheet combination with different thickness was 1.0t and 1.4t of DP780. Different steel combinations were DP780 1.0t and SPRC440 1.0t, and DP780 1.0t and DP590 1.0t. Finally dissimilar combinations was and DP780 1.0t and DP590 1.4t. The trend of low boundary and high boundaryvariation of lobe curve were analyzed with a viewpoint of the contact resistance and the heat input.Key Words : Resistance spot welding, Advanced high strength steel, Weld lobe curve, Nugget formation, Tensile shear strength

In this study, the PEHL analysis is conducted for the contact of the inner surface of the pinion gear and the pinion shaft to reveal the cause of adhesional failure on the inner surface of pinion gear of an automotive differential gear system. The numerical algorithm for the analysis of three-dimensional PEHL used in this study has advantage that the pressure and film distributions can be calculated from Reynolds equation for all mixed lubrication region without any specific boundary condition for the edge of solid contact region. Using the developed PEHL algorithm, we calculated the distributions of pressure and film thickness for the surfaces with bi-modal sine waviness at present and with single-modal crowning waviness we suggested. It is shown that the surface with the single-modal crowning waviness is more beneficial to the development of film than that with the bi-modal sine waviness.

The resistance of methicillin-resistant Staphylococcus aureus (MRSA) to all β-lactam classes limits treatment options for serious infections involving this organism. Our goal is to discover new agents that restore the activity of β-lactams against MRSA, an approach that has led to the discovery of two classes of natural product antibiotics, a cyclic depsipeptide (krisynomycin) and a lipoglycopeptide (actinocarbasin), which potentiate the activity of imipenem against MRSA strain COL. We report here that these imipenem synergists are inhibitors of the bacterial type I signal peptidase SpsB, a serine protease that is required for the secretion of proteins that are exported through the Sec and Tat systems. A synthetic derivative of actinocarbasin, M131, synergized with imipenem both in vitro and in vivo with potent efficacy. The in vitro activity of M131 extends to clinical isolates of MRSA but not to a methicillin-sensitive strain. Synergy is restricted to β-lactam antibiotics and is not observed with other antibiotic classes. We propose that the SpsB inhibitors synergize with β-lactams by preventing the signal peptidase-mediated secretion of proteins required for β-lactam resistance. Combinations of SpsB inhibitors and β-lactams may expand the utility of these widely prescribed antibiotics to treat MRSA infections, analogous to β-lactamase inhibitors which restored the utility of this antibiotic class for the treatment of resistant Gram-negative infections.

하나는 용접 전에 용접되는 재료 및 시스템의 상태를 감시하는 것이다. 두 번째는 용접 중에 발생되는 다양한 현상을 모니터링 하는 것으로 레이저 용접시 발생되는 다양한 현상을 이에 맞는 센서를 이용하여 계측하는 방법이다. 세 번째로는 용접 후 용접부의 결함 등을 모니터링 하는 것으로 접된 부위의 형상, 기공 등에 의한 불량 등을 외관검사 및 비파괴검사를 통해 검출하게 된다. 레이저 용접의 모니터링 기술은 크게 2가지 부분으로 구성된다. 하나는 다양한 센서를 이용한 하드웨어 시스템의 개발이며, 다른 하나는 계측된 신호 혹은 데이터를 이용하여 품질평가 혹은 용접부의 기계적 혹은 형상적 특성과 매칭시키는 기술이다. 본 논문에서는 레이저 용접의 모니터링 기술과 이를 활용한 데이터 처리 기술에 대하여 논하고자 한다.

Most welding element models are simplified rather than detailed to reduce analysis time and to incorporate multiple welding elements into a structure. Nevertheless, a simple model should describe the real process. Using experimental Stress — Strain (S-S) data, we found that the S — S curve of base metals is affected by the strain rate. The force of spot weld was also affected by the strain rate. This indicates that the effect of spot weld should be incorporated into FEM analysis models. The relationship between actual welding and FEM model welding was determined by detailed spot weld FEM analysis. The S — S curve of the base metal was used to determine the failure force of spot weld. As a result of this research, a final spot weld FEM model is proposed. FEM analysis using this new model, as well as an experiment impact test of the hat profile box, was performed. A comparison of FEM analysis results with experimental results demonstrated the utility and accuracy of the new model.

In this paper laser welding AA5182 of aluminum alloy with AA5356 filler wire were performed with respect to laser power, welding speed, and wire feed rate. The experiments showed that the tensile strength of the weld was higher than that of the base material under sufficient heat input conditions. A genetic algorithm was used to optimize process parameters which were the laser power, welding speed, and wire feed rate. To do that, a fitness function was formulated, taking into account weldability and productivity. A factor for the weldabilty used tensile strength estimation model which was made by neural network, and as the productivity, welding speed, and wire feed rate were used. Weld monitoring system for aluminum laser welding with filler wire was constructed through the optical sensors to measure the plasma light intensity. Relationship between monitoring signal and plasma and keyhole behavior according to welding condition was analyzed and it was found that sensor signal could express the information for weld quality. Weld quality estimation algorithm was formulated fuzzy multi feature pattern recognition algorithm using the monitoring signals. Quality prediction system was also developed to apply this algorithm to production line.

In this study, we conducted laser welding by using remote scanner that is 5J32 aluminum alloy to observe the mechanical properties and optimize welding process parameters. As the control factors, laser incident angle, laser power and welding speed were set and as the result of weldablility, tensile shear tests were performed. ANOVA (Analysis of Variation) was also carried out to identify the influence of process variables on tensile shear strength. Strength estimation models were suggested using regression alnalysis and 2nd order polynomial model had the best estimation performance. In addition optimal welding condition was determined in terms with wedalility and productivity using objective function and fitness function. Final optimized welding condition was laser power was 4 kW, and welding speed was 4.6 m/min.Key Words : Aluminum laser welding, Remote scanner, Strength estimation, Process parameters optimization 1. 서 론 최근 자동차 배기가스의 규제가 한층 심하게 강화되고 있으며, 자동차의 연비효율을 높이기 위한 연구의 중요성이 강조되고 있다. 그러므로 최근 자동차 관련 기술개발의 동향은 연비 향상, 공기 저항 감소를 위한 새로운 차체 디자인 및 재료의 경량화 등이 있다. 특히 소재의 경량화는 엔진 효율을 높여 자동차의 성능향상을 극대화시키고 이를 통해 연비 향상을 도모할 수 있으므로, 환경오염방지와 연료절감에 가장 적합하고 효과적인 방법이다. 그러므로 알루미늄 혹은 마그네슘 합금과 같은 경량 재료를 차량에 적용하는 방법이 주로 사용된다. 알루미늄 합금의 경우 열전도도가 크고 녹는점이 낮기 때문에 고 에너지 열원인 레이저 용접을 실시하며

The objective of this paper is to determine the optimal welding conditions in terms of the productivity and weldability for laser welding of aluminum alloy AA5182 using filler wire AA 5356. The experiments were performed with laser power, welding speed, and wire feed rate as control factors. Tensile tests were carried out in order to evaluate the weldability under each welding condition. In order to estimate the tensile strength, three regression models are proposed. One is a multiple linear regression model, another is a second order polynomial regression model, and the last is a multiple nonlinear regression model. Of the three models, the second order polynomial regression model had the best estimation performance with respect to ANOVA (analysis of variation) and average error rate. Also, this study defines objective functions for tensile strength, which represents weldability, and for the welding speed and wire feed rate, which represent productivity. In addition, fitness functions are obtained using the objective functions and a weight matrix which shows the importance of each objective function. The steepest descent method is used to find the optimal point where the fitness function was maximized. Optimal welding conditions were found at a filler wire feed rate of 2.7 m/min, laser power of 4 kW, and welding speed of 7.95 m/min.

Nowadays, most car manufactures have tried to improve fuel efficiency and corrosion resistance of car body. Therefore, use of high strength steels and coated steel becomes more and more increased. In this study, spot weld characteristics according to lap sequence of sheets were analyzed using simulation method for three different steel sheet of car body which were EDDQ class coated steel with 0.7t, high strength steel 440R with 1.2t and advanced high strength steel DP 590 with 1.0t. Using simulation, weldability was evaluated by nugget size of welded zone according to nugget growth curve and welding current with respect to lap sequence of sheets. Contact resistance of each sheets contact point was used to analyze formation of nugget and optimal lap sequence was suggested.

In resistance spot welding, regardless of the optimal condition, bad weld quality was still produced due to complicated manufacturing processes such as electrode wear, misalignment between the electrode and workpiece, poor part fit-up, and etc.. Therefore, the goal of this study was to measure the process signal which contains weld quality information, and to develop the process fault monitoring system. Welding force signal obtained through variety experimental conditions was analyzed and divided into three categories: good, shunt, and poor fit-up group. And then a monitoring algorithm made up of an artificial neural network that could estimate the process fault of each different category based on pattern was developed.

Bridged monobactam beta-lactamase inhibitors were prepared and evaluated as potential partners for combination with imipenem to overcome class C beta-lactamase mediated resistance. The (S)-azepine analog 2 was found to be effective in both in vitro and in vivo assays and was selected for preclinical development.