• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.251-254
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• 2011

본 논문에서는 예약주소를 사용한 HMIPv6로 각 통신 노드에 따른 그룹 군집화와 MIH 패킷의 Service Specific TLVs의 변형을 통해 기존의 핸드오버에서 좀 더 가볍고 빠른 Searching과 효율적인 인증을 이룰 수 있도록 하였다. 군집(Aggregate) 세션 단위로 자원예약을 하는 경우 종단간 SID(Session ID)와는 별도로 군집 SID를 사용하는데 MIH의 Service Specific TLVs를 통해 터널링을 이루고 변형된 Service Specific 공간을 통한 효율적인 핸드오버를 지원한다.

• 월간산업보건
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• s.262
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• pp.26-29
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• 2010

펜타클로로페놀의 현재 직업적 노출기준은 $0.5\;mg/m^3$(TLV-TWA)으로 권고하고 있다. 이 수치는 눈, 점막과 상기도의 염증과 발한, 열, 위장 불만, 시각 장해, 중추 신경계와 심혈관계 장해를 유발할 수 있는 급성 독성의 가능성을 최소로 하는 것을 목적으로 설정하였다. Chloracne는 공업용 펜타클로로페놀을 사용하거나 펜타클로로페놀을 생산하는 근로자들에 대해서 보고하였다. 펜타클로로페놀은 피부를 통해서 즉시 흡수되는데, 이 물질의 조직 독성은 펜타클로로페놀을 포함한 용액이나 펜타클로로페놀로 오염된 의류와 접촉된 사람에게서 보고되었다. 따라서 피부경고주석은 적합한 것으로 판단되었다. 펜타클로로페놀의 발암성 잠재력에 대한 명확한 증거는 간세포성과 신장에 가까운 신생물이 관찰된 설치류 생물 검정에서 발견되었다. 그러므로 본 물질은 인간에게 불명확한 관련성을 가진 동물성 발암물질(A3)로 설정하였다. 충분한 자료가 확보되지 않아 감작성 (SEN) 경고주석 또는 TLV-STEL은 권고되지 않았다. 펜타클로로페놀은 생물학적 노출지수(BEIs)가 권고된 물질이다.

• 월간산업보건
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• s.276
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• pp.27-31
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• 2011

Perfluorobutyl ethylene(PFBE)은 유기용제 혼합물에 주로 사용되는 산업화학물질로 동물에게 경구, 피부, 눈 그리고 흡입 노출되는 경우 급성 독성이 매우 낮다. Perfluorobutyl ethylene을 흰쥐에게 하루 6시간, 일주일에 5일씩 2주간을 0, 500 ppm, 5,000 ppm, 50,000 ppm을 흡입 노출시킨 연구에서 최대무작용량(no-observed-adverse effect level, NOAEL)으로 500 ppm이 결정되었으며 5,000 pm에서는 단핵 백혈구가 약간 증가하였다. 50,000 ppm에서도 병리학적 변화는 없었다. 그 후의 흡입연구는 하루 6시간, 28일간 연속적으로 흰쥐 암수에게 400 ppm, 2,000 pm, 10,000 ppm의 농도로 perfluorobutyl ethylene 증기를 노출시켰다. 최종 노출 후 흰쥐를 희생시켜 관찰한 결과, 체내 기관 무게변화를 포함한 어떠한 변화도 관찰되지 않았다. 그러나 10,000 ppm에 노출된 수컷 흰쥐 5마리 중 4마리는 작은 다중간세포질 액포가 발견되었다. Perfluorobutyl ethylene 증기 10,000 ppm에 노출된 수컷 흰쥐는 부분적으로 평균 혈액응고 촉진 시간이 감소하였다. 이 연구에서는 최대무작용량을 2,000 ppm으로 결정하였다. Perfluorobutyl ethylene의 TLV-TWA 100 ppm은 노출 후 악영향을 최소화하는데 충분한 농도이며 "피부흡수(Skin)", "감작제(SEN)" 그리고 발암성에 대한 경고주석을 설정하기에는 유용한 연구가 충분하지 않다.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.2
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• pp.176-183
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• 1999

This paper is aimed to investigate behaviour of vortex in 2-D step cavity with high Reynolds numbers$(3.2{\times}10^{3},\;10^{4},\;3{\times}10^{4},\;5{\times}10^{4}\;and\;7{\times}10^{4})$. The SOLA algorithm which is MAC type was adopted to solution method computing the flow field on irregular grid. In case of $Re=7{\times}10^{4}$ flow behavior is steady bu periodic unsteady sinusoidal fluctuation of local velocity and kinetic energy is found for $Re=10^{4}$ Continuous movements of small eddies in the secondary flow regions are discov-ered for $3{\times}10^{4}$ Generation of eddies and their active migrating behavior are detected over $Re=5{\times}10^{4}$ resulting in complete unsteady and non-linear flow characteristics Furthermore a typhoon-like vortex(TLV) appears intermittently and rotates along the separation regions and boundary layers.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.5
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• pp.67-74
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• 2019

In this paper, mathematical models of a simulation code are presented. The simulation code was developed for the startup analysis of an open cycle liquid rocket engine (LRE). Most of the components comprising an LRE, including the priming process in the propellant feeding line, were considered. A startup simulation of a 75-tonf LRE, which was used for the KSLV-II test launch vehicle (TLV), was performed. The simulation results showed good agreement with the engine acceptance test results, thus proving the validity of the startup simulation code.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.2
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• pp.86-94
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• 2010

This paper proposed an authentication interworking protocol (AIP) based on IEEE 802.21 MIH in the heterogeneous networks. The proposed AIP using the RSA signature reduces handover delay time and communication message overhead when the mobile node moves between the heterogeneous networks. It defines new AIP TLV in MIH frame format and uses the MIH Information Server (MIHIS) for proxy signature issue instead of the authentication server for the heterogeneous networks. For low handover delay, the proposed AIP performs pre-authentication processes with MIH protocol before layer 2 handover. Also, this paper analyzed the performance of the handover and compared with the non-secure MIH protocol.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.1
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• pp.32-40
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• 2008

Methyl bromide has been used as a representative fumigant for quarantine, and several poisoning cases have occurred recently by this chemical in Korea. The purpose of this study is to evaluate workers' exposures to airborne methyl bromide in the importing and exporting plant products quarantine companies. Air samples were collected 400/200 mg Anasorb 747TM and were analyzed by gas chromatograph /flame ionization detector according to the Occupational Safety and Health Agency (OSHA) Method PV2040. Geometric mean (GM) and arithmetic mean (AM) of total 27 workers' exposure concentrations to airborne methyl bromide were 1.12 ppm and 0.24 ppm, respectively. Two exposures(12.1 ppm and 12 ppm as 8hr-TWA) of total 27 workers' exposures exceeded the Korean standard (5 ppm) of Ministry Labor, while 4 exposures (15%) exceeded the Threshold Limit Value (TLV) (1 ppm) of American Conference of Governmental Industrial Hygienists (ACGIH). Seven samples (11%) of total 63 short-term air samples exceeded the OSHA Permissible Exposure Limit (PEL) 20 ppm (Ceiling). The opening (management) task in wood fumigation by tent showed the highest short-term exposure concentrations (AM: 18.6 ppm, GM: 0.58 ppm, maximum: 340.7 ppm). The maximum level in treatment task of the same process was 2.01 ppm. Methyl bromide concentrations in opening operation was significantly higher than that in treatment operation (p<0.05). In conclusion, the GM of workers' 8hr-TWA exposures to airborne methyl chloride in the importing/exporting plant quarantine industry was estimated below the ACGIH TLV (1 ppm). However, opening task in the fumigation of wood being covered with tent or fumigation of pant products in container showed the levels exceeding ACGIH TLV (1 ppm), and opening task in the fumigation of wood being covered with tent showed the level exceeding the Korean standard of Ministry of Labor (5 ppm).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.2
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• pp.158-166
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• 1999

The purpose of this study was to investigate the correlation between airborne total dust and man-made mineral fibers (MMMF), and to estimate total dust concentration to maintain below the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV$^{(R)}$) for the MMMF. The regression coefficients between airborne total dust concentrations and fiber concentrations determined in the industries producing glass fibers, rock wool. refractory ceramic and continuous filament glass fibers products were 0.41, 0.42, 0.20 and 0.19, respectively. The size characteristics of fibers as well as the amounts of contaminated non-fibrous dusts could affect the correlation intensities. When total dust and fiber exposure data were compared with the occupational exposure limits, there was a large gap between two evaluation results. The regression coefficient between total dust and fiber data was increased ($r^2=0.88$) in the process of insulation installation generating in the higher levels of glass or rock wool fibers. In this case, an estimated total dust concentration of glass wool or rock wool fibers complying with the ACGIH TLV (1 f/cc) was $1.7mg/m^3$. In conclusion, the total dust and fibers concentrations was highly correlated at the higher exposure levels so that total dust-monitoring data could be used to control simply and economically and to estimate worker's exposure to fibers.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.2
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• pp.139-152
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• 2009

According to the third study on the distribution of chemical substances carried out by the Department of Environment in 2006, there were a total of 900 chemical substances whose respective annual usage amount exceeded 1,000 tons and, among them, 90 substances belonged to the 168 hazardous substances requiring management(53.6%). The work-related illnesses caused by hazardous substances requiring management in Korea between $1992{\sim}2005$ can be classified into four groups depending on the type of the chemical substances. These four groups are 23 organic substances including benzene, 12 metals including lead, 3 acids and bases including hydrogen chloride, and 6 gaseous substances including carbon monoxide. These hazardous substances requiring management were again classified depending on the threshold limit values. The chemicals whose TLV was lower than or equal to 0.005 ppm included 4 organic substances including methylene bisphenyl isocyanate and toluene-2,4-diisocyanate (TDI). The chemicals whose TLV was larger than 51 ppm included 22 organic substances including diethyl ether and 1,2-dichloroethylene. When we classified these hazardous substances requiring management according to the categories of GHS health hazards, we found that isobutyl acetate and magnesium oxide didn't belong to the 13 health hazard categories. Among the substances whose TLV is set and whose annual usage amount is more than 0.1 million ton, we recommended 12 chemical species including 4,4'-Methylenedianiline as new hazardous substances requiring management. All the recommended substances were found to be hazardous when we classified their health hazards.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.1
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• pp.113-131
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• 1997

This study was performed to evaluate the exposure levels of worker exposed to welding fume and metals in confined spaces of a shipyard. The airborne concentration of welding fumes and metal elements in confined spaces were compared with those in open working areas. Results of the study were as follows. 1. The geometric mean of welding fume concentration in a confined space was $16.6mg/m^3$, which contained $3.9mg/m^3$ Fe, $1.2mg/m^3$ Mg, $0.8mg/m^3$ Zn, $0.008mg/m^3$ Cu, $0.008mg/m^3$ Pb, $0.005mg/m^3$ Ni, $0.003mg/m^3$ Cr, $0.003mg/m^3$ Cd. The geometric mean of welding fume concentration in open working areas was $5.2mg/m^3$, which contained $1.1mg/m^3$ Fe, $0.3mg/m^3$ Mg, $0.3mg/m^3$ Zn, $0.004mg/m^3$ Cu, $0.008mg/m^3$ Pb, $0.005mg/m^3$ Ni, $0.003mg/m^3$ Cr, $0.0003mg/m^3$ Cd. The geometric mean of welding fume concentration in confined spaces was 3,2 times higher than that in open working areas. The geometric mean concentrations of such metals as Fe, Mg, Zn, or Cu within fume in confined spaces were 2-4 times higher than those in open working areas, while little difference made such metals as Pb, Ni, Cr, Cd. 2. In 32 samples out of a total of 39 samples (82.1%) collected in confined spaces, the concentrations of welding fume exceeded TLV. while so did 19 samples out of 33 samples (57.6%) in open working areas. As for the concentrations of metals in welding flume from confined spaces, Fe exceeded TLV in 14 out of a total of 38 samples (36.8%), Mn exceeded TLV in 23 out of a total of 38 samples (60.5%). As for the concentration of metals in welding fume from open working areas, Fe exceeded TLV in 3 out of a total of 34 samples (8.8%), Mn exceeded TLV in 6 out of a total of 34 samples (17.6%). Considering additive effect among metals, in 31 out of a total of 39 samples (79.5%) collected in confined spaces, the concentrations of welding fume exceeded TLV, while so did 14 out of 38 samples (55.6%) in open working areas. 3. In respect of base metal and welding type the concentration of total welding fume by $CO_2$ gas W./mild steel was the highest, followed by semiauto MMA/mild steel, then followed by TIG or $CO_2$ gas W./stainless steel. ; as for concentration of metal within fume, a decreasing order was Fe, Zn, Mn, and Pb in $CO_2$ gas W./mild steel and semiauto MMA/mild steel, but Fe, Mn, Cr, and Ni in TIG or $CO_2$ gas W./stainless steel. 4. In case of welding base metal covered by paint, contents of Zn within red paint chip and within gray paint chip were 14.0% and 0.08% respectively, which showed a little difference, while the airborne concentrations of Zn within fume during welding base metal covered red paint and gray paint were $1.351mg/m^3$ and $1.018mg/m^3$ respectively, which showed little difference. As for Pb, contents of red paint chip and gray paint chip were 0.14% and 0.08% respectively, and the airborne concentrations within fume during welding base metal covered red paint and gray paint were $0.009mg/m^3$ and $0.007mg/m^3$ respectively, both of which showed little difference.