• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.5
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• pp.60-65
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• 2019

Since nanofluids (NFs), which are a mixture of a small amount of nanoparticles and a bulk liquid solvent, were first proposed by Stephen Choi at the Argonne National Lab in 1995, they have been considered for use in many technical studies of power cooling systems and their practical application due to their high thermal conductivity and heat transfer coefficients compared to conventional coolants. Although nanofluids are a well-known form of engineering fluid that show great promise for use in future cooling systems, their underlying physics as demonstrated in experiments remain unclear. One proven method of determining the heat transfer performance of nanofluids is measuring the concentration of nanoparticles in a mixture. However, it is experimentally inefficient to build testbeds to systematically observe particle distributions on a nanoscale. In this paper, we demonstrate the distribution of nanoparticles under a temperature gradient in a solution using molecular dynamics simulations. First, temperature profiles based on substrate temperature are introduced. Following this, the radial pair distribution functions of pairs of nanoparticles, solvents, and substrates are calculated. Finally, the distribution of nanoparticles in different heating regions is determined.

• Computers and Concrete
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• v.29 no.2
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• pp.117-126
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• 2022

The vibrational characteristic of three-layered cylindrical shell (CS) submerged in fluid with the ring support has been studied. The inner and outer layer is supposed to construct by isotropic layer. The composition of central layer is of functionally graded material type. Acoustic Wave condition has been utilized to present the impact of fluid. The central layer of cylindrical shell (CS) varies by volume fraction law that has been expressed in terms of polynomial. The main shell frequency equation has been obtained by theory of Love's shell and Rayleigh-Ritz technique. The oscillation of natural frequency has been examined under a variety of end conditions. The dependence of axial model has been executed with the help of characteristic beam function. The natural frequencies (NFs) of functionally graded material (FGM) shell have been observed of cylindrical shell along the shell axial direction. Different physical parameters has been used to examine the vibration characteristics due to the effect of volume fraction law. MATLAB software has been used to get result.

• Culinary science and hospitality research
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• v.12 no.2 s.29
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• pp.195-205
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• 2006

In this study, we investigated the quality characteristics of curd yogurt with different content of Rubus coreanus Miquel juice. Yogurt was fermented with three kinds of lactic acid bacteria(Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus casei). The changes of quality characteristics were investigated during fermentation and an acceptance test was performed after fermentation. The pH was decreased on the whole, and titratable acidity was gradually increased during fermentation. The number of viable cells was increased in case of yogurt with 1% to 4% Rubus coreanus Miquel juice, while it was inhibited in the sample with 6% and 7%. There was similar content in composition of protein, lactose, FFA, TS and NFS of curd yogurt after fermentation. Color value of curd yogurt with Rubus coreanus Miquel juice was higher in L(brightness), a(redness) and b(yellowness), compared with the control. Sensory attributes of color, odor, taste, after taste and overall acceptability of the curd yogurt with 3% Rubus coreanus Miquel juice showed highest preference among samples.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.25-28
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• 2011

최근 사이언스 컴퓨팅 분야에서 대용량 데이터가 발생하고 있고 컴퓨팅 자원들의 수요도 급증하고 있다. 이로 인해 클라우드 컴퓨팅 기술의 필요성이 중요시되고 있고 전 세계적으로 급속히 발전하고 있다. 천문 연구 분야에서 관측기기의 발전으로 대용량의 천문 데이터가 생산되고 있다. 이를 처리하기 위하여 다양한 클라우드 컴퓨팅 기술을 이용한 데이터 분석 환경이 요구되고 있다. 이러한 환경을 구축하기 위해서는 가상 인프라 자원을 효율적으로 관리할 수 있어야 한다. 현재 가상 인프라 자원을 관리하기 위해 오픈 소스를 개발하는 프로젝트들이 활발히 진행되고 있다. 본 논문에서는 오픈 소스인 Eucalyptus와 OpenNebula의 기능적인 측면을 크게 10가지로 분류하여 장단점을 비교 분석하였고 OpenNebula의 세 가지 특징인 중앙 집중화된 구조, live migration과 suspend/resume 기능, 커스터마이징 기능이 대용량 천문 응용 수행을 위한 환경을 구축하는데 반드시 필요하기 때문에 OpenNebula를 채택하였다. OpenNebula를 사용해 구축한 사이언스 클라우드 테스트베드는 NFS 서버의 별도 구성을 통한 성능 개선, 하이브리드 클라우드 컴퓨팅 환경 구축, B클래스 사설 네트워크 구성, GUI 기반 사이언스 클라우드 테스트베드 관리 및 모니터링 기능의 4가지 특징을 가지고 있다. 앞으로도 천문 연구자들에게 안정적인 서비스를 제공하기 위하여 관련 연구를 계속할 것이다.

• Journal of Sensor Science and Technology
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• v.27 no.5
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• pp.345-351
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• 2018

We employed an unprecedented technique to synthesize porous $WO_3@SnO_2$ nanofibers exhibiting core-shell and fiber-in-tube configurations. Firstly, 2-methylimidazole was uniformly incorporated in as-spun nanofibers containing ammonium metatungstate hydrate and the sacrificial polymer (polyacrylonitrile). Secondly, the 2-methylimidazole on the surfaces of nanofibers was complexed with tin(II) chloride ($SnCl_2$) via simple impregnation of the as-spun nanofibers in ethanol containing tin(II) chloride dihydrate ($SnCl_2{\cdot}2H_2O$). The presence of vacant p-orbitals in tin (Sn) and the nucleophilic nitrogen on the imidazole ring allowed for the reaction between $SnCl_2$ and 2-methylimidazole, forming adducts on the surfaces of the as-spun nanofibers. The calcination of these nanofibers resulted in porous $WO_3@SnO_2$ nanofibers with a higher surface area ($55.3m^2{\cdot}g^{-1}$) and a better response to 1-5 ppm of acetone than pristine $SnO_2$ NFs synthesized using a similar method. An improved response to acetone was achieved upon functionalization of the $WO_3@SnO_2$ nanofibers with catalytic palladium nanoparticles. This work demonstrates the potential application of $WO_3@SnO_2$ nanofibers as sensing layers for chemiresistive sensory devices for the detection of acetone in exhaled breath.

• Journal of Auto-vehicle Safety Association
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• v.12 no.3
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• pp.52-60
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• 2020

Usage of EDR(Event Data Recorder) report for traffic accident analysis is currently increasing due to government regulation of EDR data release. Nevertheless, a lot of investigators simply adopt by comparing the number of ignition cycles(crash) at event to the number of ignition cycles(download) without an exact judgment whether event data occurred by this accident or not. In the EDR report, besides ignition cycles, there are many factors such as event record type, algorithm active(rear/rollover/side/frontal), time between events, event severity status(rollover/rear/right side/reft side/frontal), belt switch circuit status, driver/passenger pretensioner/air-bag deployment, PDOF(Principal Direction of Force) by ΔV to be able to decide whether or not to adopt. also the event data is considered enough to vehicle damaged state, accident situation at the scene of the accident. and there is described in "all data should be examined in conjunction with other available physical evidence from the vehicle and scene" in the CDR(Crash Data Retrieval) report. Therefore many investigators have to decide whether or not to adopt after they consider sufficiently to above factors when they are the traffic accident analysis and investigate the causes of a accident on the adopted event data. In this paper, we report to traffic accident investigators notable points and analysis methods on the basis of thousands of cases and the results of one's own experiment in NFS(National Forensic Service).

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.301-306
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• 2015

An ultra-compact and wideband low noise amplifier (LNA) in a quad flat non-leaded (QFN) package is presented. The LNA monolithic microwave integrated circuit (MMIC) is implemented in a $0.25{\mu}m$ GaN IC technology on a Silicon Carbide (SiC) substrate provided by Triquint. A source degeneration inductor and a gate inductor are used to obtain the noise and input matching simultaneously. The resistive feedback and inductor peaking techniques are employed to achieve a wideband characteristic. The LNA chip is mounted in the $3{\times}3-mm^2$ QFN package and measured. The supply voltages for the first and second stages are 14 V and 7 V, respectively, and the total current is 70 mA. The highest gain is 13.5 dB around the mid-band, and -3 dB frequencies are observed at 0.7 and 12 GHz. Input and output return losses ($S_{11}$ and $S_{22}$) of less than -10 dB measure from 1 to 12 GHz; there is an absolute bandwidth of 11 GHz and a fractional bandwidth of 169%. Across the bandwidth, the noise figures (NFs) are between 3 and 5 dB, while the output-referred third-order intercept points (OIP3s) are between 26 and 28 dBm. The overall chip size with all bonding pads is $1.1{\times}0.9mm^2$. To the best of our knowledge, this LNA shows the best figure-of-merit (FoM) compared with other published GaN LNAs with the same gate length.

• Convergence Security Journal
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• v.13 no.3
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• pp.85-90
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• 2013

To provide high-quality services, national public institutions and companies have provided information and materials over the internet network. However, a risk of malware infection between transmission and reception of data leads to exposure to various security threats. For this reason, national institutions have proceeded with projects for network separation since 2008, and data linkage has been made using network connection storage through network separation technologies, along with physical network separation. However, the network connection storage has caused waste of resources and problems with data management due to the presence of the same data in internal network storage and external network storage. In this regard, this study proposes a method to connect internal and external network data using NAS storage as a way to overcome the limitations of physical network separation, and attempts to verify the priority of items for the optimization of network separation by means of AHP techniques.

• Environmental Analysis Health and Toxicology
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• v.25 no.4
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• pp.263-271
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• 2010

Objectives : The records of 447 pesticide poisoning deaths from the National Forensic Service (NFS) headquarters located in Seoul of Korea from 2005 to 2009 were retrospectively reviewed. Methods : The data of each case were analyzed by using the SPSS program. Results : The mean age was $57.8{\pm}14.8$ years and the range was 16-92 years. The numbers of deaths of males and females were 301 and 134, respectively. The largest number of cases occurred in people aged 50-59 years (n=92, 20.6%) followed by the age groups 40-49 years (n=91, 20.4%), 60-69 years (n=88, 19.7%), and 70-79 years (n=75, 16.8%). The total number of deaths among other age groups (10-19, 20-29, 30-39, 80-89, and 90-99 years) was 73, representing only 16.3%. Of all pesticide poisoning deaths, 96.2% were due to suicide, and 28.4% of the total number who died received medical treatment. The mostfrequent site of ingestion was the person's own residence (n=279, 62.4%). The most common classes of pesticide were bipyridylium herbicide (paraquat, 31.1%), organophosphate insecticide (21.7%), and carbamate insecticide (15.4%). The major pesticides having a high proportion of fatalities were paraquat (31.1%), methomyl (11.4%), glyphosate (9.1%), dichlorvos (5.6%), phosphamidon (4.6%), and methidathion (4.0%). Conclusions : This study showed that poisoning deaths due to pesticides are one of the major public health problems in Korea. Enforcement of regulations and safety education to prevent pesticide poisoning should be carried out by the government.

• Toxicological Research
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• v.28 no.3
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• pp.195-199
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• 2012

The records of 255 cyanide poisoning deaths obtained from National Forensic Service (NFS) headquarters, located in Seoul of Korea, from 2005 to 2010 were retrospectively reviewed. The mean age was $41.88{\pm}13.09$ and range was 6~80 years (unknown in seven cases). The number of deaths of males and females were 200 and 53, respectively (unknown in two cases). The largest number of cases occurred in people aged 40-49 years (81 cases, 31.8%), followed by the age groups 30~39 years (51 cases, 20%), 50~59 years (44 cases, 17.2%) and 20~29 years (43 cases, 16.9%). The total number of deaths among other age groups (below 10, 10~19, 60~69, 70~79, over 80 years and unknown) were 36, representing only 14.1%. Of all cyanide poisoning deaths, 97.3% were due to suicide, and 14.5% of the total number who died received medical treatment. The most frequent site for ingestion was the person's own residence (120 cases, 47.1%) and the route of administration was mainly oral (252, 98.8%). From the total of 255 cyanide poisoning cases, white powders were submitted for analysis in 92 cases. Potassium cyanide and sodium cyanide occupied 51 and 41 cases, respectively. This study showed that poisoning deaths due to cyanide are one of the continuously reported public health problems in Korea. Enforcement of regulations and safety education to prevent cyanide poisoning should be carried out by the government.