• Bulletin of the Korean Chemical Society
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• v.13 no.4
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• pp.367-375
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• 1992

The electronic structure change caused by insertion of hydrogen into the interstices of Pd cluster is studied. Several properties such as energy, reduced overlap population (ROP), electon density (ED) and density of states (DOS) are calculated by Extended Huckel Method. Various types of clusters are considered. The same is performed on Ni and Pt and all the results are compared. The results show that the hydrogen atom in Pd is stabilized remarkably but its wave function is almost unperturbed. The fact is compatible with noticeable solubility of hydrogen in Pd but may not be a positive enough evidence to rationalize the claimed cold fusion phenomenon. It is also found that a remarkable charge transfer from Pd atom to hydrogen atom occurs.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.05a
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• pp.238-241
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• 2020

클라우드 컴퓨팅 (Cloud Computing)은 언제 어디서든 인터넷을 통하여 필요한 컴퓨팅 자원을 원하는 시간만큼 활용할 수 있는 최신 컴퓨팅 방식으로 사용자에게 효율적인 컴퓨팅 자원을 제공한다. 또한 빅데이터 및 인공지능 분야에서의 활용도가 높아 4차 산업혁명의 기초 인프라로 부각되고 있다. 클라우드의 독립적인 컴퓨팅 자원을 하이퍼바이저 (Hypervisor)를 통해 효율적으로 관리한다. 본 논문에서는 클라우드 하이퍼바이저에 대한 공격 기법인 커널 기반 루트킷, 캐시 기반 부 채널 공격, ROP (Return oriented Programming) 공격의 공격 방법과 대응 방안을 분석한다. 이후 기존에 연구된 하이퍼바이저 보안을 위한 클라우드 컴퓨팅 아키텍처를 소개하고, 하이퍼바이저 구조의 취약점에 대해 고찰한다. 마지막으로 하이퍼바이저 기반 클라우드 컴퓨팅 아키텍처의 문제점과 해결방안을 고찰한다.

• Economic Analysis
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• v.25 no.2
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• pp.1-53
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• 2019

This paper examines monetary policy quantitatively in a two-agent and small-scale New-Keynesian economy with debt-constrained households that cannot smooth their consumption intertemporally and frictionlessly since highly indebted households are not allowed to borrow above a certain debt ceiling in incomplete financial markets without additional risk premiums due to information asymmetry between savers and borrowers. We find that, in the event of cost shocks, the asymmetric responses of borrowing households without, and saving households with, dividend incomes lead to different labor supplies and consumptions over heterogeneous households, and eventually to an extension of the monetary policy transmission channels. The income effect and low elasticity of the labor supply play key roles in such asymmetric responses over heterogeneous households. We also find that the social welfare in a flexible inflation targeting (FIT) monetary policy, in which both the inflation gap and the output gap are considered in an integrated manner when policy-making, is similar to that of the Ramsey optimal monetary policy (ROP), in which the shares of debt-constrained households, as well as all economic states, including both the inflation gap and output gap, are considered comprehensively for policy-making, and that it is greater than that of simple inflation targeting (SIT) monetary policy, in which only the inflation gap is considered mechanically for policy-making. Such social welfare implies that a FIT policy may still work even in an economy with a sizable number of debt-constrained households. Further, the responses of cost shocks to consumption and labor supply are dying out more slowly under FIT and ROP policies than under an SIT policy.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.1
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• pp.49-56
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• 2008

Reliability has been considered as an important design measure in various industrial systems. We discuss a reliability optimization problem with component choices (ROP-CC) subject to a budget constraint. This problem has been known as a NP-hard problem in the reliability design fields. Several researchers have been working to find the optimal solution through different heuristic methods. In this paper, we describe our development of simulated annealing (SA) and tabu search (TS) algorithms and a reoptimization procedure of the two algorithms for solving the problem. Experimental results for some examples are shown to evaluate the performance of these methods. We compare the results with the solutions of a previous study which used ant system (AS) and the global optimal solution of each example obtained through an optimization package, CPLEX 9.1. The computational results indicate that the developed algorithms outperform the previous results.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.2
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• pp.107-116
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• 2016

Premature babies of less than 37 weeks gestation might require oxygen therapy as an integral part of treatment and respiratory support. Because of their under-developed lungs, these so-called "preemies" might contract respiratory distress syndrome (RDS). To treat RDS, neonatal oxygen therapy is administered, where controlled oxygen gas is measured as a fraction of inspired oxygen ($FiO_2$). However, exposure to high oxygen content during long treatment could cause oxygen intoxication, which might cause permanent blindness due to retinopathy of prematurity (ROP), whereas insufficient oxygen exposure could cause severe hypoxia. A doctor would use oxygen saturation ($SpO_2$) data and prescribe a dose of $FiO_2$ to maintain $SpO_2$ within a suitable range. One objective is to maintain $SpO_2$ within the acceptable range using $FiO_2$ that is as low as possible. Adjustment of $FiO_2$ would normally be done by nurses every 15 to 30 minutes, which might not be safe in many situations. An error in $FiO_2$ adjustment during a manual procedure could be as large as +/- 2.5%. This paper presents a system that can determine an $FiO_2$ value suitable to the current $SpO_2$ and that automatically adjusts $FiO_2$ with an error clearance of +/- 0.25%.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.788-791
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• 2008

On this study, following works have been carried out : division of Han River Basin into 24 sub basins, use of rainfall data of 151 stations to make spatial distribution of rainfall, selection of control points such as Soyanggang Dam, Chungju Dam, Chungju Release Control Dam, Heongseong Dam, Hwachun Dam, Chuncheon Dam, Uiam Dam, Cheongpyung Dam and Paldang Dam, selection of SSARR (Streamflow Synthesis and Reservoir Regulation) model as a hydrologic model, preparation of input data of SSARR model, sensitivity analysis of parameter using hydrologic data of 2002. The sensitivity analysis showed that soil moisture index versus runoff percent (SMI-ROP), baseflow infiltration index versus baseflow percent (BII-BFP) and surface-subsurface separation (S-SS) parameters are higher sensitive parameters to the simulation result.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.956-963
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• 2020

Dose optimization for Radioactive Occupational Personal (ROP) is an important subject in nuclear and radiation safety field. The geometric environment of a nuclear facility is complex and the work area is radioactive, so traditional navigation model and radioactive data field cannot form an effective environment model for dose assessment and dose optimization. The environment model directly affects dose assessment and indirectly affects dose optimization, this is an urgent problem needed to be solved. Therefore, this paper focuses on an environment model used for Dose Assessment and Dose Optimization (DA&DO). We designed a multi-layer radiation field coupling modeling method, and then explored the influence of the environment model to DA&DO by virtual simulation. Then, a simulation test is done, the multi-layer radiation field coupling model for nuclear facilities is demonstrated to be effective for dose assessment and dose optimization through the experiments and analysis.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1800-1808
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• 2013

Dual-responsive amphiphilic block copolymers were synthesized by combining enzymatic ring-opening polymerization (eROP) of ${\varepsilon}$-caprolactone (CL) and ATRP of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA). The obtained block copolymers were characterized by gel permeation chromatography (GPC), $^1H$ NMR and FTIR-IR. The critical micelle concentration (CMC) of copolymer was determined by fluorescence spectra, it can be found that with hydrophilic block (PDMAEMA) increasing, CMC value of the polymer sample increased accordingly, and the CMC value was 0.012 mg/mL, 0.025 mg/mL and 0.037 mg/mL for $PCL_{50}$-b-$PDMAEMA_{68}$, $PCL_{50}$-b-$PDMAEMA_{89}$, $PCL_{50}$-b-$PDMAEMA_{112}$, $PCL_{50}$-b-$PDMAEMA_{89}$ was chosen as drug carrier to study in vitro release profile of anti-cancer drug (taxol). The temperature and pH dependence of the values of hydrodynamic diameter (Dh) of micelles, and self-assembly of the resulting block copolymers in water were evaluated by dynamic light scattering (DLS). The result showed that with the temperature increasing and pH decreasing, the Dh decreased. Drug-loaded nanoparticles were fabricated using paclitaxel as model. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) had been explored to study the morphology of the hollow micelles and the nanoparticles, revealing well-dispersed spheres with the average diameters both around 80 nm. In vitro release kinetics of paclitaxel from the nanoparticles was also investigated in different conditions (pH and temperature, etc.), revealing that the drug release was triggered by temperature changes upon the lower critical solution temperature (LCST) at pH 7.4, and at $37^{\circ}C$ by an increase of pH.

• Neonatal Medicine
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• v.25 no.1
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• pp.29-36
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• 2018

Purpose: The purpose of this study was to investigate the outcome after changes in the treatment strategies for very low birth weight infant (VLBWI) in a single neonatal intensive care unit (NICU) center. Methods: We performed a retrospective review of 300 VLBWI born from 1st January 2010 to 31th December 2016. We compared the outcomes including survival rate, birth weight (BW), gestational age (GA), and morbidities between period I (2010-2013, P-I) and period II (2014-2016, P-II). Results: The average survival rate was not different between P-I and P-II. However, the survival rate of ${\leq}24$ weeks' GA, 25 weeks' GA, 26 weeks' GA were 57%, 69%, 93% respectively in P-II and 31%, 59%, 87% in P-I respectively. The survival rate of infants with birth weight <500 g, 500-749 g, 750-999 g were 100%, 55%, 90% respectively in P- II and 50%, 24%, 80%, respectively in P-I. The incidence of bronchopulmonary dysplasia (BPD) was higher in P-II than in P-I (P=0.012) and moderate-to-severe BPD was also higher in P-II (P=0.004). Incidence of patent ductus arteriosus (PDA) with treatment, necrotizing enterocolitis (stage ${\geq}2$), and abnormal brain sonography were significantly lower in P-II (P=0.027, P=0.032, P=0.005). Incidences of retinopathy of prematurity (ROP) with laser treatment and early sepsis were not different. Conclusion: The survival rate and complications of VLBWI were improved in period II, especially in less than 750 g and below 26 weeks, except incidence of BPD. Changes of NICU strategies were effective to improve mortality and morbidity in VLBWI.

• Journal of Pharmaceutical Investigation
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• v.41 no.2
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• pp.95-102
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• 2011

An amphiphilic cationic branched methoxy poly (ethylene glycol)-branched polyethylenimine - poly(L-phenylalanine) (mPEG-bPEI-pPhe) block copolymer was successfully synthesized by ring-opening polymerization (ROP) of N-carboxyanhydride of L-phenylalanine (Phe-NCA) with mPEG-bPEI for the preparation of more stable polyelectrolyte complex (PEC) included a hydrophobic interaction. mPEG-bPEI was firstly prepared by the coupling of mPEG and bPEI using hexamethylene diisocyanate (HMDI). The structural properties of mPEG-bPEI-pPhe copolymers were confirmed by $^1H$ NMR. The copolymers exhibited a self-assemble behavior in water above critical aggregate concentration (CAC) in the range of 0.01-0.14 g/L. The CAC of copolymers obviously depended on the hydrophobic block content in the copolymers (the value decreased with the increase of the pPhe block content). The cationic copolymers have the ability to form multi-interaction complex (MIC) with bovine serum albumin (BSA) and plasmid DNA through multi-interaction (electrostatic and hydrophobic interaction). The physicochemical characterization of the complex was carried out by the measurement of zeta potential and particle size. Their zeta-potentials were positive (approximately +10 mV) and their sizes decreased with increasing pPhe contents in the copolymers (PPF/BSA wt% ratio = 2). The complex showed good stability at high ionic strength. Therefore, mPEG-bPEI-pPhe block copolymer was considered as a potential material to enhance the stability of complex including biotherapuetic drugs.