• Journal of Advanced Marine Engineering and Technology
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• 제17권5호
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• pp.44-53
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• 1993

In this paper, we discuss on the control algorithm to make the wheeled inverse pendulum type mobile robot move in two dimensional plane. The robot considered in this paper has two independently driven wheels in same axel which suport and move it-self, and is assumed to have the fyro type sensor to know the inclination algle of the body and rotary encoders to know wheel's rotation angular velocity. The control algorithm is divided into three parts. The first part is for the posture and velocity control for forward-backward direction, the second is the steering control, and the last part is for the control of total system to track the given trajectory. We handle the running velocity control of the robot as part of the posture control to keep the balance because the posture relates deeply with the velocity and can be controlled by the velocities of the wheels. The control problem is analyzed as the tracking control, and the controller is realized with the state feedback and feed-forward of the reference velocity. Constructing the control system which contained one intergrator in forward path, we also realized the control system without observer for the estimation of the accumulated errors in the inclination angle of the body. To prevent the robot from being unstable state by sudden variation of the reference velocity when it starts and stops, or changes velocity, the reference velocity of which acceleration is slowly changing, is ordered to the robot. To control its steering, we give the different reference velocities for both wheels which are calculated from the desired angular velocity of the body. Finally, we presents the experimental results of the experimental robot Yamabico Kurara in which the proposed control algorithm had been implemented.

• 분석과학
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• 제25권1호
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• pp.7-13
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• 2012

제주도 고산지역에서 라돈($^{222}Rn$)을 실시간 모니터링하여 대기 중의 배경농도 수준을 확인하였다. 고산지역의 라돈 농도는 평균 2831 $mBq/m^3$ (0.077 pCi/L)로 우리나라 실내 평균농도보다는 19.5배 낮은 배경농도 수준을 나타내었다. 계절별로는 봄, 여름, 가을, 겨울에 각각 2657, 2071, 3249, 3384 $mBq/m^3$ 농도를 보여 겨울에 높고 여름에 낮은 것으로 조사되었다. 월별로는 10월에 가장 높고 7월에 가장 낮은 농도를 나타내었다. 일간 농도는 오전 7시에 하루 중 가장 높은 농도를 보였고, 오후 2~3시경에 가장 낮은 농도를 나타내는 것으로 확인되었다. 역궤적 분석 결과, 라돈 농도는 기류의 유입경로에 따라 차이를 보였고, 아시아대륙으로부터 제주도로 이동했을 때 농도가 높고 북태평양으로부터 기류가 유입될 때 훨씬 더 낮은 농도를 나타내었다.

• 한국환경과학회지
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• 제31권6호
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• pp.503-513
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• 2022

This research investigated the effect of the eruption of Japan Sakurajima volcano on the concentration of ultrafine particle when the north Pacific high pressure exists in the Busan in summer. As a result of analyzing the forward trajectory using the HYSPLIT model, the air parcel from Sakurajima volcano passed through the sea in front of Busan at 1500 LST on July 17, 24 hours after the volcanic eruption. As a result of analyzing the PM₁₀ and PM_2.5 concentrations in the Busan for two days from July 16 to 17, 2018, the Sakurajima eruption in Japan, it can be seen that there was a high increase in PM₁₀ and PM_2.5 concentrations compared to the previous day. As a result of analyzing the backward trajectory, the air mass that reached Busan at 1300 LST on July 17, 2018 has moved near the Sakurajima volcano at 1,500 m, 2,000 m, and 3,000 m. The concentration of SO₄^2- in PM_2.5, the concentration of all three stations in Busan showed a sharp increase from 1000 LST on July 17th. Looking at the NH₄⁺ concentration in PM_2.5, it shows a very similar variation trend to SO₄^2-, and the correlation coefficient between the two components is 0.96 for Jangrimdong and Yeonsandong, and 0.85 for Busan New Port. Looking at the NO₃^- concentration in PM_2.5, the same high concentrations as SO₄² and NH₄⁺ were not observed in the afternoon of July 17th.

• 한국환경과학회지
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• 제21권7호
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• pp.855-863
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• 2012

This study analyzed mass concentrations of TSP, PM10 and PM2.5 and elemental constituents according to the isentropic backward trajectories of air parcel from Cheongwonin East Asia during the period January - October, 2011. Mass concentrations of the continental polluted airflow (CP) showed levels of TSP and PM10 mass concentrations higher than the continental background airflow (CB). Also, PM2.5 mass concentrations of anthropogenic fine particles ran higher in CP than in CB. The elemental constituents and elemental constituent ratio ended up varying depending on the origin of atmospheric aerosols generated. The average absolute content of elemental constituents reached its height in CB, the ratio of anthropogenically originating elements (PE) among the all elements (AE) analyzed marked a high in CP, and Mg+Na/AE reached its height in the oceanic airflow (OA). At the same time, TSP, PM10 and PM2.5 mass concentrations, the ratio of PM2.5/TSP and PE/AE element ratio ran higher in CP than CB. Episodes of large-scale transport of atmospheric pollutants as observed at Cheongwon were 8 cases and 22 days. The ratios of PM10, PM2.5 among TSP mass concentrations showed different results and the ratios of PM2.5 showed an increasing trend in the episodes of anthropogenic air pollution transport. Overall, dustfall episodes show a level of elemental constituents higher than those of anthropogenic air pollution.Dustfall episodes were observed to contain more of Fe, Al and Ca originating from continental soils and those of air pollution were observed to contain more of Zn, Mn, Cu and Pb. By difference in contents of absolute elemental constituents, episodes of anthropogenic air pollution showed a high PE/AE rate, and dustfall episodes a high SE/AE rate.

• 한국대기환경학회지
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• 제20권1호
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• pp.69-76
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• 2004

Asian Dust samples were collected in the ambient air of Seosan, Western Korea, in spring of 2000∼2002. PM (Particulate Matter) concentrations were 199,8$\mu\textrm{g}$/㎥ in the first Asian Dust period (March, 23∼24) and 249.4$\mu\textrm{g}$/㎥ in the second period (April, 7∼9) of 2000. Compared with the concentrations in 2000, relatively low PM concentrations, 157.3$\mu\textrm{g}$/㎥ were measured in the periods of 2001 (April, 24∼26). Especially high PM concentration 953.1$\mu\textrm{g}$/㎥ were measured in the periods of 2002 (March, 21∼22). The variation in the PM concentration was observed according to the time for the formation of Asian dust. Considering the particle size distributions of Asian dust, a high concentration was also observed in coarse particle region. The results of backward trajectory model showed the route of the dust storms from northern area of Mongol and Gobi desert. Various mycelia grown from fungal spores were observed on the PM samples and identified at the genus level. All the genera from the three years (2000∼2002), Fusarium, Aspergillus, Penicillium, Basipetospora, Epicoccum and Monotospora are hyphomycetes in the division Fungi imperfecti (Deuteromycota). Fungal composition on the dust sample in March, 2000 was similar to the result of March, 2002. However, the result of April, 2001 was obviously different from the other dust periods. The variations of fungal compositions between the dust periods could be caused by the trajectories of the dust storms.

• 한국대기환경학회지
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• 제12권1호
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• pp.79-90
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• 1996

Total suspended particles were measured at Kosan, Cheju Island, Korea during the period of March 11 .sim. April 19, 1994. Concentrations of non-sea salt(nss) ions were higher than those measured at clean marine areas in Japan and other background marine areas in the world. Especially, nss sulfate concentration is compatable to thoes measured at Seoul. It is suggested that most nss sulfate concentration is originated from anthropogenic sources. Nss sulfate concentration shows strong correlation with ammonium and nss potassium concentrations while shows no a pparent correlation with nitrate and nss calcium concentrations. Nss calcium concentrations shows strong correlation with nss potassium and mss magnesium concentrations. It is deduced that nss potassium has two origins, one anthropogenic, the other crustal. Backward trajectory analysis results show the trajectories of air parcel during the measurement period were mostly originated from China. It is shown that cases of high nss sulfate with high nss calcium can occur when an air parcel originated from arid and semi-arid regions of morthwestern China or Mongolia passes through northeastern China.

• 한국대기환경학회지
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• 제9권4호
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• pp.329-339
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• 1993

Due to the global-convection currents, transboundary transport of air pollutants is widely observed in many regions of the world. This study was carried out to investigate the pattern of long-range transport of air pollutants in North East Asia, especially the impact of air pollutants originated in China and Japan on the air quality in Korea. From the meteorological data at the 850 mb surface from May 1986 through April 1987 at 54 obsevation stations in the North East Asia region, the backward and forward trajectories were calculated using interpolation method. And the contributions of pollution sources in neighbor countries to the air quality in Korea were analyzed. It was concluded that air pollution in China had a great influence on the air quality in Korea throughout the year : it could be transported to Korea just within 2 or 3 days most of the time. The trajectory analysis showed that pollution sources in Beijing. Liaoning Province, and Shandong Province, the most heavily industrialized areas in China., were the most influential for the air quality in Korea except for summer season. Durnig summer season, the air pollution in Shanhai and Japan could have moer influence on Korea. Such transboundary transport of air pollutants necessitate international cowork and cooperation in the region of North East Asia.

• 한국대기환경학회지
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• 제12권1호
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• pp.91-99
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• 1996

Ozone, sulfur dioxide, and nitrogen oxides were measured at Kosan, Cheju Island, Korea during the period of March 11 .sim. April 19, 1994. During the measurement period, the average SO$_{2}$ and NOx concentrations were about 0.97 ppb and 3.5 ppb, respectively. Average NO concentration was below the detection limit and thus the effect of NO during the period was negligible. The concentrations of SO$_{2}$ and Nox were lower than those at other urban area in Korea but higher than other remote areas in the world. Average $O_{3}$ concentration for the period was about 55 ppb, slightly higher than or comparable to those at remote marine areas in the world. Detailed analyses of trend of gaseous species concentrations show that the effects of local NO emission sources for NOx concentration were significant during the period, while those of local SO$_{2}$ emission sources were not high. Backward trajectory analysis results show that when SO$_{2}$ or $O_{3}$ concentration was higher than the average concentrations, the air parcels were transported from China.

• 한국환경과학회지
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• 제21권3호
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• pp.327-337
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• 2012

Air pollution inventories are aggregated around south-eastern part of the Korean Peninsular including Busan, Ulsan, and Changwon cities. Because densely populated cities are concentrated in this region, air pollutants emitted from one of these cities tend to be impacted on the air quality of other cities. In order to clarify the seasonal movement pattern of emitted particles, several numerical simulations using WRF/FLEXPART were carried out. Four cases were selected for each season. The Weather Research and Forecasting model (WRF) reproduced atmospheric flow fields with nested grids. The seasonal pattern of air mass of study area was determined by backward and forward trajectories. As a result, the air parcel moves from northwest to southeast due to northwesterly winds in spring and winter. Also air parcel transports from south to north in summer, and moves from west to east. Because the air mass moves differently in each season, these characteristics should be considered when performing air quality analysis.

• 한국대기환경학회지
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• 제28권5호
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• pp.595-605
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• 2012

Fine particles ($PM_{2.5}$) were collected and analyzed from April 2010 through January 2011 in Chungju to investigate the characteristics of $PM_{2.5}$ and its ionic species. The annual mean concentrations of $PM_{2.5}$, ${SO_4}^{2-}$, $NO_3{^-}$, and $NH_4{^+}$ in the particulate phase were 40.84, 7.61, 7.14 and $3.74{\mu}g/m^3$, respectively. $PM_{2.5}$ concentrations were higher in fall and spring than in winter and summer. The elevated concentrations episodes are the main factor that enhanced the $PM_{2.5}$ concentrations in the fall. Among the major ionic species ${SO_4}^{2-}$ showed the highest concentration, followed by $NO_3{^-}$ and $NH_4{^+}$, $NO_3^-$ exhibited higher concentrations during the winter, but ${SO_4}^{2-}$ and $NH_4{^+}$ were not showed seasonal variation. The high correlations were found among $PM_{2.5}$, ${SO_4}^{2-}$, $NO_3{^-}$ and $NH_4{^+}$ during all seasons except for spring. The evaluation of backward trajectories and meteorological records show that the highest $PM_{2.5}$ concentration levels occurred during W-NW weather conditions, which influenced by the emission sources of China area. The low pollution levels generally occurred during E-S weather conditions, which influenced by the East Sea and south of the Yellow Sea. The elevated $PM_{2.5}$ mass concentrations arouse the concentration of $NO_3{^-}$, but no effects on ${SO_4}^{2-}$ and $NH_4{^+}$.