Search Results

You are looking at 1 - 8 of 8 items for

  • Author: Dong-Jin Lee x
Clear All Modify Search
Open access

Jong-Ho Nam, Dong-Ham Kim and Ho Jin Lee

ABSTRACT

A concept of preliminary design for mid-size superyachts is explored. First, the profile of a superyacht is interactively designed with the help of freeform curve functionality and graphical user interface (GUI) based interaction. The hull form is then constructed using major characteristic curves such as design waterline, deck sideline, and sections in addition to the predefined profile curve. After exterior hull modeling is done, the arrangement of significant interior spaces of all decks is carried out. A genetic algorithm is exploited to find a space arrangement by considering space fitness values, space proximity, and stairs connectivity of relevant spaces. A goal of the paper is to offer a step-by-step procedure for superyacht design from scratch or when initial information is not sufficient for complete design. For this purpose, a GUI based superyacht design system is developed. This design approach is expected to help users interactively design mid-size superyachts.

Open access

Sung-Duk Kim, Ho-Jin Lee and Byoung-Dong Oh

Investigation on Application of Parshall Flume for Flow Measurement of Low-Flow Season in Korea

The accurate determination of the flow rate of the low flow season is a very important factor in setting and running a water resources development plan. Because South Korea undergoes a lot of flood damage due to localized heavy rain during the summer season, flow rates are measured mostly according to flood management, and this allows for a lack in research in understanding low flow season flow rates. In order to estimate the accurate flow rate of a low flow season, the present study has used the Parshall flume that has been used widely in flow measurements, and has reviewed the applicability. A Parshall flume was installed in an actual river and the measured flow rate that was obtained from the flow rate formula and velocity measurements, that were suggested by the ISO and the USBR, were found to be very accurate when compared to the flow rate computation results by the Parshall flume. By using the state-discharge rating curve equation that is most commonly used at the level gauging station, the flow rate was estimated and compared with the flow rate by the Parshall flume. The results showed an approximate 14% error with the estimation from the state-discharge rating curve equation. Therefore, using the Parshall flume to estimate the flow rate of low flow season is more effective than the state-discharge rating curve equation.

Open access

Sang Park, Dong Lee, Hyung-Jin Baek, Jeongran Lee and Muhammad Farooq

Study of the genetic diversity of Korean, Chinese and Japanese landraces of barley (Hordeum vulgare L.) using microsatellites

Barley (Hordeum vulgare L.) is one of important winter cereals in the world and has been the subject of numerous genetic investigations. Studies of its genetic diversity based on germplasm have a significant impact on crop breeding and conservation of genetic resources. This study was conducted to reveal the genetic diversity in barley landraces from Korean, Chinese and Japanese populations and evaluate the discrimination ability of SSR markers, distributed uniformly throughout the barley genome. Seven SSR primers were used to screen a set of 737 diverse barley landraces from Korea, China and Japan. The observed number of alleles per locus (Na), the effective number of alleles (Ne), and the mean gene diversity (He) were 11.14, 3.6245 and 0.7048, respectively. The number of alleles per locus was highest in Chinese landraces (8.9 alleles), followed by Korean (8.6) and Japanese (6.4). In this regard, HVKASI primer may be useful to distinguish Japanese landraces from others, as this unique allele was only detected at 175 bp in Japanese landraces. The average value of genetic distance was D=0.935. The largest genetic distance (D=1.209) among the three regional (representing each country in general) populations was found between Korean and Japanese populations. Based on the UPGMA dendrogram, four major groups can be distinguished at the similarity value of 0.43. The scatter plot showed overlapping in the central part amongst 3 groups of barley landraces. SSR markers are a powerful tool to examine functional diversity. Rich barley gene pool can be very useful for meeting current and future challenges in barley raising.

Open access

Hyo-Seob Kim, Fikret Yilmaz, Peyala Dharmaiah, Dong-Jin Lee, Tae-Haeng Lee and Soon-Jik Hong

Abstract

In the present work, Cu and Ni nanofluids were synthesized using the pulsed wire evaporation (PWE) method in the different aqueous medias, namely (ethanol and ethylene glycol), and the effects of the aqueous media on the dispersion state, stability, and particle size of nanoparticles were studied. The size and morphology of synthesized nano-particles were investigated by transmission electron microscopy (TEM). Also, the dispersion stability of the nanofluids was evaluated by turbiscan analysis. The TEM results showed that the nano-particles were spherical in shape, and the average particle size was below 100 nm. The average particle size of the Cu nano-particles was smaller than that of Ni, which was attributed to a difference in the specific sublimation energy of the elements. Moreover, ethylene glycol (EG) exhibited higher suspension stability than ethanol. Finally, the dispersion stability of Cu@EG displayed the highest value due to lower particle size and greater viscosity.

Open access

Sradhanjali Singh, Haragobinda Srichandan, Ashish Pathak, Chandra Sekhar Gahan, Sujeong Lee, Dong-Jin Kim and Byoung-Gon Kim

Abstract

The moderate thermophilic mix culture bacteria were used to depyritize the Illinois coal of varying particle sizes (-100 μm, 100-200 μm, +200 μm). Mineral libration analysis showed the presence of pyrite along with other minerals in coal. Microbial depyritization of coal was carried out in stirred tank batch reactors in presence of an iron-free 9K medium. The results indicate that microbial depyritization of coal using moderate thermophiles is an efficient process. Moreover, particle size of coal is an important parameter which affects the efficiency of microbial depyritization process. At the end of the experiment, a maximum of 75% pyrite and 66% of pyritic sulphur were removed from the median particle size. The XRD analysis showed the absence of pyrite mineral in the treated coal sample. A good mass balance was also obtained with net loss of mass ranging from 5-9% showing the feasibility of the process for large scale applications.

Open access

Dong-Sup Lee, Dae-Seung Cho, Kookhyun Kim, Jae-Jin Jeon, Woo-Jin Jung, Myeng-Hwan Kang and Jae-Ho Kim

ABSTRACT

Independent Component Analysis (ICA), one of the blind source separation methods, can be applied for extracting unknown source signals only from received signals. This is accomplished by finding statistical independence of signal mixtures and has been successfully applied to myriad fields such as medical science, image processing, and numerous others. Nevertheless, there are inherent problems that have been reported when using this technique: instability and invalid ordering of separated signals, particularly when using a conventional ICA technique in vibratory source signal identification of complex structures. In this study, a simple iterative algorithm of the conventional ICA has been proposed to mitigate these problems. The proposed method to extract more stable source signals having valid order includes an iterative and reordering process of extracted mixing matrix to reconstruct finally converged source signals, referring to the magnitudes of correlation coefficients between the intermediately separated signals and the signals measured on or nearby sources. In order to review the problems of the conventional ICA technique and to validate the proposed method, numerical analyses have been carried out for a virtual response model and a 30 m class submarine model. Moreover, in order to investigate applicability of the proposed method to real problem of complex structure, an experiment has been carried out for a scaled submarine mockup. The results show that the proposed method could resolve the inherent problems of a conventional ICA technique.

Open access

Min-Jin Kim, Dong Sam Kim, Hun-Seok Yoon, Wook Jae Lee, Nam Ho Lee and Chang-Gu Hyun

ABSTRACT

A number of seaweed species are used as traditional foods and medicine in different parts of the world, including Asian countries. However, very few data on the anti-melanogenic effect of seaweed have been published. Undaria pinnatifida (Dolmiyeok), a brown alga, is a traditional food in Jeju Island, the southern regions of the Korea peninsula. In this study, ethylacetate extracts of U. pinnatifida (UPE) were examined for their anti-melanogenic potentials. Our results supports the finding that UPE down-regulated melanin content in a dose-dependent pattern. To clarify the target of UPE action in melanogenesis, we performed Western blotting for tyrosinase and microphthalmia-associated transcription factor (MITF), which are key melanogenic enzymes. UPE inhibited tyrosinase and MITF expressions in a dose-dependent manner. These results indicate that treatment with UPE significantly inhibits the melanogenesis in B16 cells, and may be effective in the whitening agent for the skin

Open access

Dong Jin Kim, Joon-Ho Oh, Han Soo Kim, Young Soo Kim, Manhee Jeong, Chang Goo Kang, Woo Jin Jo, Hyojeong Choi, Jong Guk Kim, Seung Hee Lee and Jang Ho Ha

Abstract

TlBr single crystals grown using the vertical Bridgman-Stockbarger method were characterized for semiconductor based radiation detector applications. It has been shown that the vertical Bridgman-Stockbarger method is effective to grow high-quality single crystalline ingots of TlBr. The TlBr single crystalline sample, which was located 6 cm from the tip of the ingot, exhibited lower impurity concentration, higher crystalline quality, high enough bandgap (>2.7 eV), and higher resistivity (2.5 × 1011 Ω·cm) which enables using the fabricated samples from the middle part of the TlBr ingot for fabricating high performance semiconductor radiation detectors.