A Novel Design of Suspension System for Driver's Seat

Thanh-Tung Luu(Thanh-Tung Luu),박성태(Sung-Tae Park) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_2

A driver's seat can be modeled with a suspension system of spring, mass and damper. To increase the capacity of anti-vibration, the natural frequency should be decreased as low as possible. In this paper, the method to decrease the natural frequency by the potential energy is introduced. In addition, the experiment is done on a small model to prove the theorem.

Propensity to Innovate and Firm Performance in the Developing Economies: Evidence from ASEAN Countries

Duy Tran Luu,Truong Vinh Tran Luu 아시아기술혁신학회 2023 Asian Journal of Innovation and Policy Vol.12 No.2

This paper employs datasets from the Enterprise Survey conducted by the World Bank to examine the relationship between four types of innovation defined by the Oslo Manual (OECD, 2005): product innovation, process innovation, marketing innovation, organization innovation, and the firm performance in the selected developing ASEAN economies. The main objective of this paper is to understand the characteristics of innovation activities at the firm level and how various innovation types affect firm performance. The empirical results from ASEAN manufacturing firms reveal that product innovation positively affects firms’ performance, while non-technological innovations are negatively related to the performance of firms. The further employed quantile regression provides more insights into the roles of innovation types on different levels of firm performance: while product and process innovations actively contribute to the small and medium-size firms (below 25th quantile and median), organizational and marketing innovations negatively affect them. Interestingly, the role of process innovation decreases when firm performance grows.

Investigation of the Microstructure of Mechanically Milled Nd40Fe30Co15Al10B5 Alloy

Luu Tien Hung,Nguyen Huy Dan 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

The microstructure of Nd40Fe30Co15Al10B5 alloys fabricated by using a high-energy ball-milling method was investigated by using high-resolution transmission electron microscopy (HRTEM), scan- ning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), selected area electron diraction (SAED) and electron backscatter diraction (EBSD) techniques. The crystalline phases found in the alloys were the tetragonal Nd2(Fe,Co,Al)14B (denoted as the 2 : 14 : 1 phase), the tetragonal Nd6(Fe,Co,Al)14 (denoted as the phase) and the fcc Nd-rich (a = 0.51 nm) phases. The formation of 2 : 14 : 1 crystallites supposedly contributed to the high coercivities up to 24 kOe for the alloys. The microstructure of Nd40Fe30Co15Al10B5 alloys fabricated by using a high-energy ball-milling method was investigated by using high-resolution transmission electron microscopy (HRTEM), scan- ning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), selected area electron diraction (SAED) and electron backscatter diraction (EBSD) techniques. The crystalline phases found in the alloys were the tetragonal Nd2(Fe,Co,Al)14B (denoted as the 2 : 14 : 1 phase), the tetragonal Nd6(Fe,Co,Al)14 (denoted as the phase) and the fcc Nd-rich (a = 0.51 nm) phases. The formation of 2 : 14 : 1 crystallites supposedly contributed to the high coercivities up to 24 kOe for the alloys.

Biodiezel in Vietnam-Potentiality and Opportunity of Development

( Luu Hoang Ngoc ),( Mai Ngoc Chuc ) 한국공업화학회 2008 한국공업화학회 연구논문 초록집 Vol.2008 No.-

Neural Network Model for Construction Cost Prediction of Apartment Projects in Vietnam

Luu, Van Truong,Kim, Soo-Yong Korea Institute of Construction Engineering and Ma 2009 한국건설관리학회 논문집 Vol.10 No.3

Accurate construction cost estimation in the initial stage of building project plays a key role for project success and for mitigation of disputes. Total construction cost(TCC) estimation of apartment projects in Vietnam has become more important because those projects increasingly rise in quantity with the urbanization and population growth. This paper presents the application of artificial neural networks(ANNs) in estimating TCC of apartment projects. Ninety-one questionnaires were collected to identify input variables. Fourteen data sets of completed apartment projects were obtained and processed for training and generalizing the neural network(NN). MATLAB software was used to train the NN. A program was constructed using Visual C++ in order to apply the neural network to realistic projects. The results suggest that this model is reasonable in predicting TCCs for apartment projects and reinforce the reliability of using neural networks to cost models. Although the proposed model is not validated in a rigorous way, the ANN-based model may be useful for both practitioners and researchers. It facilitates systematic predictions in early phases of construction projects. Practitioners are more proactive in estimating construction costs and making consistent decisions in initial phases of apartment projects. Researchers should benefit from exploring insights into its implementation in the real world. The findings are useful not only to researchers and practitioners in the Vietnam Construction Industry(VCI) but also to participants in other developing countries in South East Asia. Since Korea has emerged as the first largest foreign investor in Vietnam, the results of this study may be also useful to participants in Korea.

Effect of Pap smears on the long-term survival of cervical cancer patients: a nationwide population-based cohort study in Korea

Luu Xuan Quy,Lee Kyeongmin,Jun Jae Kwan,Suh Mina,Jung Kyu-Won,임명철,최귀선 한국역학회 2022 Epidemiology and Health Vol.44 No.-

OBJECTIVES: This study aimed to investigate the effect of cervical cancer screening by Papanicolaou (Pap) smears on the long-term survival of cervical cancer patients. METHODS: We constructed a retrospective cohort of 14,903 women diagnosed with invasive cancer or carcinoma in situ in 2008 and 2009 and followed up until December 31, 2019, by using individual-level data from 3 national databases of the Korean National Cancer Screening Program, the Korean Central Cancer Registry, and death certificates. Cox proportional-hazards regression was used to investigate the effect of cervical cancer screening on mortality. RESULTS: In total, 12,987 out of 14,867 patients (87.4%) were alive at the end of the follow-up period (median: 10.5 years). Screened patients had a 38% lower risk of cervical cancer death than never-screened patients (hazard ratio [HR], 0.62; 95% confidence interval [CI], 0.54 to 0.70). Screening was associated with 59% and 35% lower risks of death, respectively, in screened patients with localized and regional stages. Furthermore, lower HRs among women who received screening were observed in all age groups, especially women aged 50–59 years (HR, 0.54; 95% CI, 0.42 to 0.69). The lowest HR for cervical cancer death was reported among patients screened within the past 2 years (HR, 0.54; 95% CI, 0.47 to 0.63), and the HRs increased with increasing time intervals. CONCLUSIONS: Pap smear screening significantly reduced the risk of cervical cancer-specific death in Korean women across all cancer stages.

Effect of mammography screening on the long-term survival of breast cancer patients: results from the National Cancer Screening Program in Korea

Luu Xuan Quy,Lee Kyeongmin,Jun Jae Kwan,Suh Mina,Jung Kyu-Won,최귀선 한국역학회 2022 Epidemiology and Health Vol.44 No.-

OBJECTIVES: This study investigated the effect of mammography screening on the long-term survival of breast cancer (BC) patients aged 40 years or older according to their screening history and duration since screening. METHODS: The study cohort was organized from 3 nationwide databases of the Korean National Cancer Screening Program, the Korean Central Cancer Registry, and death certificates. We included 24,387 women diagnosed with invasive BC or ductal carcinoma in situ in 2008 and 2009 and followed up until December 31, 2019. Cox proportional-hazards regression was used to investigate the effect of BC screening on the risk of death. RESULTS: Overall, 20,916 of 24,387 patients (85.8%) were alive at the end of the follow-up period (median: 10.5 years). The long-term survival rate was significantly lower in the never-screened group (80.3%) than in the screened group (88.9%) (p< 0.001). A 35% reduction in the risk of BC death (hazard ratio [HR], 0.65; 95% confidence interval [CI], 0.60 to 0.70) from screening was observed. A subgroup analysis according to the cancer stage showed 62%, 36%, and 24% lower risks of BC death for the localized stage, regional stage, and distant stage, respectively. Women aged 40-49 years received the least benefit from BC screening (HR, 0.71; 95% CI, 0.62 to 0.81). CONCLUSIONS: Mammography screening was effective in reducing the risk of BC-specific death in Asian women across all cancer stages. However, this effect was relatively small among women in their 40s, suggesting that more detailed and specialized screening strategies are needed for that age group.

2D vibration analysis of circular arches with constant double symmetric cross-sections using isogeometric approach

Luu, A. T.,Kim, N. I.,Lee, J. Springer Science + Business Media 2017 KSCE Journal of Civil Engineering Vol.21 No.7

Automatic Suggestion for PubMed Query Reformulation

Luu Anh Tuan,Jung-jae Kim 한국정보과학회 2012 Journal of Computing Science and Engineering Vol.6 No.2

Query reformulation is an interactive process of revising user queries according to the query results. To assist biomedical researchers in this process, we present novel methods for automatically generating query reformulation suggestions. While previous work on query reformulation focused on addition of words to user queries, our method can deal with three types of query reformulation (i.e., addition, removal and replacement). The accuracy of the method for the addition type is ten times better than PubMed’s “Also try”, while the execution time is short enough for practical use.

Effect of thickness on the microstructure and soft magnetic properties of CoFeHfO thin films

Luu Van Tho,이광은,김철기,김종오 한국물리학회 2008 Current Applied Physics Vol.8 No.6

The thickness effects on the microstructure and soft magnetic properties of CoFeHfO thin films have been investigated in the range of 100–600 nm. There was a significant change in the coercivity (Hc) and the anisotropy (Hk) value with increasing film thickness, but the saturation induction and the resistivity almost remain unchanged. Hc and Hk reached a minimum value of 0.19 Oe and a maximum value of 50 Oe, respectively at 200 nm film thickness. The high saturation magnetic induction is 21 kG and resistivity is 500μΩ cm. The origin of the changing Hc and Hk values is discussed in detail based on change of microstructure along with film thickness. The thickness effects on the microstructure and soft magnetic properties of CoFeHfO thin films have been investigated in the range of 100–600 nm. There was a significant change in the coercivity (Hc) and the anisotropy (Hk) value with increasing film thickness, but the saturation induction and the resistivity almost remain unchanged. Hc and Hk reached a minimum value of 0.19 Oe and a maximum value of 50 Oe, respectively at 200 nm film thickness. The high saturation magnetic induction is 21 kG and resistivity is 500μΩ cm. The origin of the changing Hc and Hk values is discussed in detail based on change of microstructure along with film thickness.