IMPACT BEHAVIOR MODELING OF MOTORCYCLE FRONT WHEEL-TIRE ASSEMBLY

K. S. TAN,S. V. WONG,R. S. RADIN UMAR,N. K. GUPTA,A. M. S. HAMOUDA 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.3

Experiments were conducted to investigate the influence of certain parameters that affect the impact response of the motorcycle front wheel-tire assembly under various impact conditions. Impact tests were conducted according to 2V 5–1 fractional factorial design using a pendulum impact test apparatus with impact speed, impact mass, tire inflation pressure level, striker geometry, and impact location as design factors. Significant factors influencing the response of the wheel-tire assembly were identified. Coefficients for each factor were also determined, and empirical models were then developed for each response. An analysis indicates that the developed models fit well within the experimental ranges of the respective factors. However, for several interaction effects, the models become unrealistic, whereby they give certain deformation values when approaching zero impact mass and/or zero impact velocity. This is not consistent with the mechanics of the physical world, as there should not be any significant deformation when delivered impact energy is small enough. Efforts have been made in developing better models to resolve the inconsistency and to include a wider range, especially considering the case of the lower limit of experimental factors, which are an impact mass of 51.18 kg and/or an impact velocity of 3 m s−1 (10.8 km/h) down to zero. The minimum amount of impact energy required to produce the onset of observable deformation on the wheel was incorporated in the development of new models. Finally, the present models have been developed not only to cover the lower regions but also to range up to the upper limits of the factors, which are an impact mass of 101.33 kg and an impact velocity of 6 m s−1 (21.6 km/h). Experiments were conducted to investigate the influence of certain parameters that affect the impact response of the motorcycle front wheel-tire assembly under various impact conditions. Impact tests were conducted according to 2V 5–1 fractional factorial design using a pendulum impact test apparatus with impact speed, impact mass, tire inflation pressure level, striker geometry, and impact location as design factors. Significant factors influencing the response of the wheel-tire assembly were identified. Coefficients for each factor were also determined, and empirical models were then developed for each response. An analysis indicates that the developed models fit well within the experimental ranges of the respective factors. However, for several interaction effects, the models become unrealistic, whereby they give certain deformation values when approaching zero impact mass and/or zero impact velocity. This is not consistent with the mechanics of the physical world, as there should not be any significant deformation when delivered impact energy is small enough. Efforts have been made in developing better models to resolve the inconsistency and to include a wider range, especially considering the case of the lower limit of experimental factors, which are an impact mass of 51.18 kg and/or an impact velocity of 3 m s−1 (10.8 km/h) down to zero. The minimum amount of impact energy required to produce the onset of observable deformation on the wheel was incorporated in the development of new models. Finally, the present models have been developed not only to cover the lower regions but also to range up to the upper limits of the factors, which are an impact mass of 101.33 kg and an impact velocity of 6 m s−1 (21.6 km/h).

Edge perturbation on electronic properties of boron nitride nanoribbons

K.L. Wong,K.W. Lai,M.W. Chuan,Y. Wong,A. Hamzah,S. Rusli,N.E. Alias,S. Mohamed Sultan,C.S. Lim,M.L.P. Tan Techno-Press 2023 Advances in nano research Vol.15 No.5

Hexagonal boron nitride (h-BN), commonly referred to as Boron Nitride Nanoribbons (BNNRs), is an electrical insulator characterized by high thermal stability and a wide bandgap semiconductor property. This study delves into the electronic properties of two BNNR configurations: Armchair BNNRs (ABNNRs) and Zigzag BNNRs (ZBNNRs). Utilizing the nearest-neighbour tight-binding approach and numerical methods, the electronic properties of BNNRs were simulated. A simplifying assumption, the Hamiltonian matrix is used to compute the electronic properties by considering the self-interaction energy of a unit cell and the interaction energy between the unit cells. The edge perturbation is applied to the selected atoms of ABNNRs and ZBNNRs to simulate the electronic properties changes. This simulation work is done by generating a custom script using numerical computational methods in MATLAB software. When benchmarked against a reference study, our results aligned closely in terms of band structure and bandgap energy for ABNNRs. However, variations were observed in the peak values of the continuous curves for the local density of states. This discrepancy can be attributed to the use of numerical methods in our study, in contrast to the semi-analytical approach adopted in the reference work.

Modeling of low-dimensional pristine and vacancy incorporated graphene nanoribbons using tight binding model and their electronic structures

Wong, K.L.,Chuan, M.W.,Chong, W.K.,Alias, N.E.,Hamzah, A.,Lim, C.S.,Tan, M.L.P. Techno-Press 2019 Advances in nano research Vol.7 No.3

Graphene, with impressive electronic properties, have high potential in the microelectronic field. However, graphene itself is a zero bandgap material which is not suitable for digital logic gates and its application. Thus, much focus is on graphene nanoribbons (GNRs) that are narrow strips of graphene. During GNRs fabrication process, the occurrence of defects that ultimately change electronic properties of graphene is difficult to avoid. The modelling of GNRs with defects is crucial to study the non-idealities effects. In this work, nearest-neighbor tight-binding (TB) model for GNRs is presented with three main simplifying assumptions. They are utilization of basis function, Hamiltonian operator discretization and plane wave approximation. Two major edges of GNRs, armchair-edged GNRs (AGNRs) and zigzag-edged GNRs (ZGNRs) are explored. With single vacancy (SV) defects, the components within the Hamiltonian operator are transformed due to the disappearance of tight-binding energies around the missing carbon atoms in GNRs. The size of the lattices namely width and length are varied and studied. Non-equilibrium Green's function (NEGF) formalism is employed to obtain the electronics structure namely band structure and density of states (DOS) and all simulation is implemented in MATLAB. The band structure and DOS plot are then compared between pristine and defected GNRs under varying length and width of GNRs. It is revealed that there are clear distinctions between band structure, numerical DOS and Green's function DOS of pristine and defective GNRs.

Irradiation time-dependent study of eggshell-derived hydroxyapatite powder synthesized by microwave-assisted wet chemical precipitation method

K.W. Goh,Y.H. Wong,R.S.K. Singh,Hari Chandran,S.K. Wong,K.Y. Sara Lee 한양대학교 세라믹연구소 2022 Journal of Ceramic Processing Research Vol.23 No.2

The extraction of calcium from natural biowaste material such as chicken eggshells have been shown to be viable to synthesiscalcium phosphate bioceramic. In this work, eggshell-derived hydroxyapatite powder was synthesised by using the wetchemical precipitation technique coupled with microwave irradiation at low power (700 W) at varying exposure time from 5to 30 min. The derived nano-powders were examined to determine the phases present, chemical bonding and microstructuralevolution. It was revealed that the irradiation time has an effect on the degree of crystallinity and both the crystallite andparticle size of the derived powders although the hydroxyapatite phase stability was not disrupted. An exposure time of 15 min. was determined to be sufficient when subjected to low power microwave irradiation to formed a well-defined needle-likehydroxyapatite particles having an average crystallite size of about 22 nm. On the contrary to many literatures, this study hasdemonstrated the viability of synthesizing a useful bioceramic from using biowaste eggshells coupled with microwaveirradiation at low power of 700 W for very short period of time to produce nano-range needle-like hydroxyapatite particlessuitable for biomedical application.

Polymorphisms Associated with Resistance and Cross-Resistance to Aminoglycosides and Capreomycin in Mycobacterium tuberculosis Isolates from South Korean Patients with Drug-Resistant Tuberculosis

Via, L. E.,Cho, S.-N.,Hwang, S.,Bang, H.,Park, S. K.,Kang, H. S.,Jeon, D.,Min, S. Y.,Oh, T.,Kim, Y.,Kim, Y. M.,Rajan, V.,Wong, S. Y.,Shamputa, I. C.,Carroll, M.,Goldfeder, L.,Lee, S. A.,Holland, S. M. American Society for Microbiology 2010 Journal of clinical microbiology Vol.48 No.2

MONEY, INFLATION, AND STOCK RETURNS IN THE PACIFIC BASIN MARKETS

S R Lee,K Matthew Wong People&Global Business Association 1996 Global Business and Finance Review Vol.1 No.2

This study examines the relationship between stock returns and inflation in Japan, South Korea, and Taiwan. Stock returns in these Pacific Basin markets are found robe related negatively to inflation. A Vector Autoregressive (VAR) modelling technique is employed to delineate the various channels of influence in a system with inflation, stock returns, money supply, production, and government deficits. The findings support the argument that the negative relationship between stock returns and inflation in all three market is spurious, caused by the counter cyclical monetary policy. In addition, only Japan appears to monetize its deficits that further reinforces the effects of the counter cyclical policy.

Crystallinity Effects on the heat Distortion Temperature (HDT) of Semi-crystalline Polymers

Wong, A . C . Y .,Ng, N . S . K . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.3

Three semi-crystalline polymers were carefully injection moulded with different mould cooling temperatures for the investigation of crystallinity effects on the heat distortion tempetature (HDT). It was found that the HDT of PP was more affected by the cooling temperature than LDPE and HDPE. In addition, for PP a linear correlation was found to exist between the HDT and T_(mould). It was also demonstrated that rate of deflection and range of temperature within which continuous deflection took place were also affected by the cooling temperature. The findings are believed of practical significance for product design.

The metaphyseal sleeve: an unexplored option in the treatment of complex primary knee osteoarthritis

Wong W. K.,Chua H. S. 대한슬관절학회 2020 대한슬관절학회지 Vol.32 No.-

Background: In an ever-aging society that as a whole has become more affluent, significant emphasis has been accorded to an improved quality of life. Knee osteoarthritis is ever-increasingly treated with total knee arthroplasty. The benefits and satisfaction experienced by those who have undergone total knee replacements (TKR) are well documented in the literature. The issue arises when osteoarthritis of the affected knee is more complex than simple osteoarthritis, i.e. the patient has complex primary osteoarthritis. This collective term encompasses conditions such as massive bone loss, ligamentous laxity, coronal defects and those with contractures. There are various classifications to describe massive bone loss but we utilized the Anderson Orthopaedic Research Institute (AORI) classification. Numerous treatment options are available and we report the use of metaphyseal sleeves as a highly successful treatment option. Methods: We retrospectively reviewed all the patients at our centre who underwent primary TKR using the metaphyseal sleeves. Patients were assessed on symptoms and functional status, and radiographs were also taken to assess for osseointegration. Only patients who completed 2 years of follow up were included in our study. Results: The updated (2011) Knee Society Score (KSS) was used in conjunction with radiological assessments at each follow up. Mean KSS scores improved from 53.83 preoperatively to 193.39 postoperatively. All patients demonstrated increasing osseointegration throughout follow up. Conclusion: The metaphyseal sleeve is an excellent treatment option for complex primary osteoarthritic knees with good results objectively, functionally and radiologically and would be a great choice for all orthopaedic surgeons to include in their armamentarium.

Is Adjuvant Transarterial Chemoembolization Useful for Hepatocellular Carcinoma?

( Wong Hoi She ),( Cheung Tan To ),( Simon H. Y. Tsang ),( Wing Chiu Dai ),( Albert C. Y. Chan ),( Kenneth S. H. Chok ),( Kelvin K. C. Ng ),( Chung Mau Lo ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: Hepatectomy is the well-established curative treatment for hepatocellular carcinoma (HCC). However, adjuvant therapy is still controversial. This study tried to look into the effect of transarterial chemoembolization (TACE) in patients receiving hepatectomy for HCC. Methods: This is a retrospective study held in a single institution using prospectively maintained database for all the patients who underwent hepatectomy for HCC between January 2000 - December 2015. The perioperative details, pathological data and outcome were studied. Patients were matched at 1:10 ratio with comparable tumor size, number, indocyanine green retention test at 15 minutes, Child’s grading and tumor staging. The Kaplan-Meier method was used for survival analysis. The log-rank test was used for survival comparison. Results: There were total 1316 patients underwent hepatectomy for HCC. 38 patients with TACE were identified, and matched with 380 patients without TACE. The patients’ characteristics including age, sex, comorbidity, Child’s grading, ICG, tumor size and numbers were the same. The median sizes of the tumor were similar (9cm in TACE vs 8cm). There was no difference in terms of intraoperative management, extent of hepatectomy and postoperative complications. There were more patients with margin involvement in TACE group (23.7% vs 7.9%, p=0.004). The staging of the disease showed no significant difference in both groups. The disease free survival was similar (12.6 (TACE) vs 10.1months, p=0.794). There was no difference in overall survival with median survival of 27.8 (TACE) vs 36.9 months (5-year overall survival of 27.9% vs 41.2%, p=0.941). Conclusions: Margin involvement was known to be adverse factor for survival. Adjuvant TACE may benefit high-risk HCC patients with margin involvement as shown to have similar survival for those patients without margin involvement.

Improvised methods for tackling big data stream mining challenges: case study of human activity recognition

Fong, S.,Liu, K.,Cho, K.,Wong, R.,Mohammed, S.,Fiaidhi, J. Springer Science + Business Media 2016 The Journal of supercomputing Vol.72 No.10

<P>Big data stream is a new hype but a practical computational challenge founded on data streams that are prevalent in applications nowadays. It is quite well known that data streams that are originated and collected from monitoring sensors accumulate continuously to a very huge amount making traditional batch-based model induction algorithms infeasible for real-time data mining or just-in-time data analytics. In this position paper, following a new data stream mining methodology, namely stream-based holistic analytics and reasoning in parallel (SHARP), a list of data analytic challenges as well as improvised methods are looked into. In particular, two types of decision tree algorithms, batch-mode and incremental-mode, are put under test at sensor data that represents a typical big data stream. We investigate whether and to what extent of two improvised methods-outlier removal and balancing imbalanced class distributions-affect the prediction performance in big data stream mining. SHARP is founded on incremental learning which does not require all the training to be loaded into the memory. This important fundamental concept needs to be supported not only by the decision tree algorithms, but by the other improvised methods usually at the preprocessing stage as well. This paper sheds some light into this area which is often overlooked by data analysts when it comes to big data stream mining.</P>