A Study of Blocking Probability in WDM Network

Kiyoung Jung,JunKyun Choi 한국정보과학회 2002 한국정보과학회 학술발표논문집 Vol.2002 No.1

NUMERICAL MODELING FOR N-HEPTANE SPRAY COMBUSTION PROCESSES WITH VARIOUS AMBIENT OXYGEN CONCENTRATIONS

Kiyoung Jung,Minjun Kwon,Sewon Kim,Sungwook Park,김용모 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.3

This work has numerically analyzed the structure of spray flames with various ambient oxygen concentrations. To realistically predict the spray evaporation characteristics in the high-pressure diesel-like environment, the present study has employed the high-pressure effective conductivity vaporization model. The detailed n-heptane/air chemistry is represented by 114 elementary steps and 44 chemical species. The Representative Interactive Flamelet (RIF) model is adopted to consider the interactions between turbulence and chemistry in the fast transient reacting flows. In order to account for the spatial inhomogeneity of the scalar dissipation rate, the multiple RIFs are introduced. Moreover, the present approach realistically models the vaporization effects on the mixture fraction fluctuations. For the various conditions of ambient oxygen concentration, numerical results are compared with experimental data including the ignition delay and the lift-off length. These results indicate that the present MRIF approach yields the reasonably good agreement with experimental data in terms of ignition delay time and lift-off length. To gain the physical insight into the two-stage ignition behavior of diesel fuels, the detailed discussions are also made for the temporal evolution of several key species (CH2O, OH, CO) mass fraction and maximum temperature of the transient flamelet as well as the flame stabilization mechanism of the n-heptane spray flames with the much lower ambient oxygen concentration.

The E3 Ubiquitin Ligase COP1 Regulates Thermosensory Flowering by Triggering GI Degradation in Arabidopsis

Kiyoung Jang,Su-Jin Jung,Hong Gil Lee,Nam-Chon Paek,Pil Joon Seo 한국육종학회 2015 한국육종학회 심포지엄 Vol.2015 No.07

Floral transition is influenced by environmental factors such as light and temperature. Plants are capable of integrating photoperiod and ambient temperature signaling into their developmental program. Despite extensive investigations on individual genetic pathways, little is known about the molecular components that integrate both pathways. Here, we demonstrate that the RING finger–containing E3 ubiquitin ligase CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) acts as an integrator of photoperiod and ambient temperature signaling. In addition to the role in photoperiodic destabilization of CONSTANS (CO), COP1 also regulates temperature sensitivity by controlling the degradation of GIGANTEA (GI). COP1-impaired mutants showed reduced sensitivity to low ambient temperature. Notably, COP1 is more stabilized at low temperature and accelerates GI turnover in a 26S proteasome-dependent manner. The direct association of GI with the promoter of FLOWERING LOCUS T (FT) depends on ambient temperature, and thus COP1-triggered GI turnover delays flowering at low temperatures via a CO-independent pathway. Taken together, our findings indicate that environmental conditions regulate the stability of COP1, and conditional specificity of its target selection stimulates proper developmental responses and ensures reproductive success.

REAL-FLUID MODELING FOR TURBULENT MIXING PROCESSES OF N-DODECANE SPRAY JET UNDER SUPERCIRITICAL PRESSURE

Kiyoung Jung,Yongmo Kim,Namsu Kim 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.2

The multi-environment probability density function (MEPDF) approach using the real-fluid Equation of State (EoS) has been developed to numerically investigate the physical processes of the non-cryogenic n-dodecane fuel spray jet under the supercritical pressure. The MEPDF approach together with the conserved scalar formulation and the real-fluid library is utilized to account for the scalar fluctuation effects on the turbulent mixing processes of real fluids over the transcritical and supercritical spray conditions. To correctly predict the highly non-linear thermodynamic properties over a wide range of pressures and temperatures, this approach has adopted the RK-PR equations of state and dense-fluid correction models. In order to realistically and efficiently predict the supercritical spray jet with the strong anisotropic turbulence, the present study has adopted the RANS-based v2 -f model and the LES-based turbulence model. Simulations are made for the “Spray-A” benchmark case in the Engine Combustion Network. Based on numerical results, the detailed discussions are also made for the prediction capability of RANS/LES based real-fluid approach as well as the essential features of the real-fluid n-dodecane jet under the supercritical pressure.

순위 기반 분기한정법과 군집분석을 활용한 인간공학적 콘솔 배치 최적화 방법 개발

정기효(Kihyo Jung),김재정(Jaejung Kim),이원섭(Wonsup Lee),유택호(Taekho You),이백희(Baekhee Lee),정진은(Jineun Jung),김기영(Kiyoung Kim),홍원기(Wongi Hong),최원범(Wonbeom Choi),박세권(Seikwon Park),장수영(Sooyoung Chang),유희천(Heecheon 대한산업공학회 2018 대한산업공학회지 Vol.44 No.3

Designing an optimal component layout for an ergonomic console is important for the effective and efficient operation by its users. This study developed a console layout optimization method using a priority-based branch-and-bound algorithm and a clustering analysis. The proposed method starts with a priority-based branch and bound algorithm which searches all feasible layouts having scores higher than a designated score (e.g., 80 out of 100). Next, the objective function computes scores for the searched layouts by considering four allocation criteria (importance, frequency, sequence of use, and functional grouping) and two ergonomic criteria (reach and visibility). Lastly, the clustering analysis on the searched layouts extracts a small number of representative layouts for a designer to select the most preferred. The proposed layout optimization method was applied to component layout design of a radar console to examine its effectiveness.

부모의 방임이 자녀의 발달 및 문제행동에 미치는 영향 - 빈곤의 조절효과를 중심으로 -

정윤모(Yoonmo Jung), 이기영(Kiyoung Lee) 사회복지정책실천회 2016 사회복지정책과 실천 Vol.2 No.1

This study examines the effects of parental neglect on children’s development and behavioral problem focusing on moderating effect of poverty. Research subjects are 711 elementary students from 4th grade to 6th grade, who are selected from Korean Welfare Panel Study. Descriptive statistics, Pearson correlations, independent sample t-test, and hierarchical regression were employed to verify relationship between parental neglect, poverty, children’s development and behavioral problem. Also, simple slope test was conducted to assess moderating effect of poverty. Participant’s socio-demographic variables includes gender, age, peer relation, parents’ academic background and age, household types and family size. Children of normal(not poor) households are 476 cases(66.9%) and children of poor households are 235 cases(33.1%). All subjects are in school grade from 4th to 6th. The results of the study are as follows: First, the gaps between the participants who belongs normal households and who belongs poor households were not shown except on academic achievements area. Second, higher level of parental neglect decreases children’s development and increases behavioral problem. Third, the influence of poverty on children’s development and behavioral problem was statistically insignificant. Fourth, poverty moderates the relationship between parental neglect and children’s attention concentration as well as parental neglect and children’s self-esteem. Based on these findings, the implications were discussed. Further studies should be discussed including variety meanings of poverty. Also, decent measurement scale of parental neglect should be developed as well as parental abuse. Finally, qualitative research should be studied for both parents and children.

Effect of p-GaN hole concentration on the stabilization and performance of a graphene current spreading layer in near-ultraviolet light-emitting diodes

Jung-Hong Min,Tae Hoon Seo,Sang-Bae Choi,Kiyoung Kim,Jun-Yeob Lee,박문도,김명종,Eun-Kyung Suh,Jongryeol Kim,Dong-Seon Lee 한국물리학회 2016 Current Applied Physics Vol.16 No.10

We have demonstrated the effect of p-GaN hole concentration on a graphene current spreading layer (CSL) for stabilization and improved performance of a near-ultraviolet light-emitting diode (NUV LED). While NUV LEDs with a more lightly-doped p-GaN showed poor electrical and optical properties and unstable performance, NUV LEDs with more heavily-doped p-GaN (~2 1017 cm3) showed very stable, outstanding performance. The main factor of the improvement was the enhanced contact property between the graphene CSLs and the p-GaN that resulted from the increase of the hole concentration, which led to a thinner barrier and an enhanced current injection. From our results, we were able to determine that hole concentration as heavy as 2 1017 cm3 in p-GaN layers is a primary condition in NUV LEDs with graphene-based CSLs.

Efficacy evaluation of syringe pump developed for continuous drug infusion

Jung, Bongsu,Seo, Kwang-Suk,Kwon, Suk Jin,Lee, Kiyoung,Hong, Suyong,Seo, Hyounsoon,Kim, Gi-Young,Park, Geun-Mook,Jeong, Juhee,Seo, Soowon The Korean Dental Society of Anesthsiology 2016 Journal of Dental Anesthesia and Pain Medicine Vol.16 No.4

Background: In dental intravenous sedation, continuous intravenous infusion of a low-dose drug requires an infusion pump such as a syringe pump. To develop a new syringe pump for clinical use, the functions of the pump must meet certain international standards. Various safety and efficacy tests must be performed on the syringe pump, as stipulated by these standards, and an approval must be received from the approving agency based on such test results. Methods: The authors of the present study developed a novel syringe pump and performed efficacy evaluation by testing its infusion speed at 1 and 25 ml/h, and infusion performance testing at 2 and 24 h. Moreover, performance evaluation was conducted by comparing the novel pump to an existing pump with the infusion speed varied from 1 to 5 ml/h. Results: In the efficacy testing on the newly developed syringe pump, infusion with the infusion speed initially set to 1 ml/h resulted in infusion speeds of 1.00 and 0.99 ml/h in the 2- and 24-h assessment, respectively. Changing the infusion speed setting to 25 ml/h resulted in an infusion speed of 25.09 and 23.92 ml/h in the 2- and 24-h assessment, respectively. These results show no significant differences when compared with other commercially available pumps. Conclusions: The efficacy testing of the newly developed syringe pump showed the accuracy to be within tolerance. Based on these findings, we believe that the newly developed syringe pump is suitable for clinical use.

Does National Culture Influence the Firm’s Choice of Debt Maturity?

Kiyoung Chang,Jung-Bum Wee,Ha-Chin Yi 한국재무학회 2011 한국재무학회 학술대회 Vol.2011 No.09

Debt is an effective mechanism to mitigate agency costs in relieving manager-shareholder conflicts. Similarly, a choice over maturity of debt allows the firm to discipline entrenched managers. We show cross-country evidence that national culture along with corporate governance factor influences the lender’s (or the borrower’s) choice over the firm’s debt maturity. Using Hofestede’s frameworks (1980, 1991), uncertainty avoidance index (UAI), masculinity (MAS), and long-term orientation (LTO) indices are negatively related to overall debt maturity in country. This implies that the risk-averse lenders offer (or, borrowing firms use) short-term maturity debt when surrounding economic environment becomes more uncertain and ambiguous. This is consistent with literatures that national cultural tendency play a critical role in determining financing decision in the presence of uncertainty and ambiguity. We argue that national culture is one of the last factors to the puzzle of disparity of debt maturities across countries. The relative effect of national culture and corporate governance on firms’ debt maturity selection depends on whether a country’s financial system is bank-based economy (e.g., Japan and Germany) or market-based economy (e.g., U.S. and U.K.).

Helium Bubble Formation in Neutron Absorber Material Irradiated in Spent Nuclear Fuel Pool

Jung, Yunsong,Kim, Kiyoung,Ahn, Sangjoon AMERICAN NUCLEAR SOCIETY 2018 Transactions of the American Nuclear Society Vol.119 No.-