• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.4
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• pp.454-459
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• 2016

Pre- or post-harvest processing is required to mitigate the risk of norovirus infection mediated by shellfish or seafood. We investigated the environmental resistance of human norovirus (HuNoV) under various conditions of temperature, salinity, and pH in seawater. Male-specific coliphage (MSC) was as the reference virus for all tests. At 4℃, HuNoV GII4 spiked into seawater was continually detected by RT-PCR for 35 days, regardless of salinity or pH level. It maintained nearly stable concentrations, meaning HuNoV can sustain a viral population in seawater long enough to be accumulated by shellfish and other filter feeders during winter. MSC was also stable at 4℃ although viral infectivity dropped sharply after 28 days. The effects of salinity and pH on MSC were indistinct. At 25℃ the detectable period of HuNoV GII4 by RT-PCR in seawater decreased to about one-third or half of the period at 4℃. High salinity (32 psu) and alkaline pH (8.5) were also unfavorable for sustaining HuNoV abundance at 25℃ in seawater. The resistance patterns of MSC to high temperature, high salinity, and alkaline pH were more dramatic and viral infectivity decreased over time, almost in direct proportion to experimental days. MSC was undetectable after 12 days under all salinities and pH levels at 25℃.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.4
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• pp.439-458
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• 2005

An automated analysis system for water soluble constituents in $PM_{2.5}$ has been developed. The system consists of a high capacity multi tube diffusion scrubber (MTDS), a low temperature particle impactor (LTPI), and two ion (anion and cation) chromatography (IC) systems. Atmospheric particles have been collected by passing sample air through a thermostated MTDS followed by a LTPI. This system allows simultaneous measurements of soluble ions in $PM_{2.5}$ at 30 minutes interval. At the air sampling flow rate of 1.0L/min, the detection limits of the overall system are in the order of tens of $ng/m^3$. This system has been successfully used for the measurement of particulate components of Seoul air from April 2003 to January 2004. $SO_4^{2-},\;NO_3^-,\;NH_4^+,\;NO_2^-,\;Cl^-,\;Na^+,\;K^+,\;Ca^{2+},\;and\;Mg^{2+}$ are the major ionic species for $PM_{2.5}$ at Seoul. Among them, $SO_4^{2-},\;NO_3^-\;and\;NH_4^+$ are the most abundant ions, contributed up to $86\%$ of the total and the concentrations were higher than those in any other urban sites in the world except for Chinese cities. There are high pollutant episodes which contribute about $15\~20\%$ of annual average values of the major ions. During the episode, the all parcels were transported from the asian continent and $PM_{2.5}$ were significantly neutralized. This suggests that aged and long range transported pollutants caused the high pollutant episodes. They showed a distinct daily and seasonal variations:they showed a peak in the early morning caused by the night-time accumulation of particulate matters. Atmospheric reactions including gas-to-particle reactions and inter-particle reactions and meteorological parameters including relative humidity and ambient temperature were described with related to the $PM_{2.5}$ 5 concentrations. All of the ionic species showed higher concentrations during the spring than those for summer and winter.

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.3
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• pp.99-107
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• 2012

There has been increasing number of patients with asthma, rhinitis, and conjunctivitis due to the atmospheric pollution and global warming. In this study, we investigated daily observed number of pollens to establish a standardized method for the impact analysis of the climate changes on the number of daily pollens in Korea. Daily observed allergenic pollens of trees, weeds, and pine were analyzed during the period of 1998 to 2010 (except 2006) in Seoul, Busan, Daegu, Gwangju, Gangneung, and Jeju. They increased in large cities including Seoul during the last 12 years and the long-term trend may continue in the future. Daily concentration or amount of pollens was highly correlated with weather variables. Positive correlation was found between air temperature and the pollens although different relationships existed for different locations. Chill days were utilized to estimate the length of the flowering or pollen period. The pollen period of trees was shorter in the field when the winter temperature was low. This approach may be utilized to determine the quantitative change in length of the pollen season in the future.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.242-252
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• 2016

A process-based ecosystem model, BIOME-BGC, was applied to simulate seasonal and inter-annual dynamics of carbon and water processes for potential evergreen needleleaf forest (ENF) biome in Korea. Two simulation sites, Milyang and Unljin, were selected to reflect warm-and-dry and cool-and-wet climate regimes, where massive diebacks of pines including Pinus densiflora, P. koraiensis and P thunbergii, were observed in 2009 and 2014, respectively. Standard Precipitation Index (SPI) showed periodic drought occurrence at every 5 years or so for both sites. Since mid-2000s, droughts occurred with hotter climate condition. Among many model variables, Cpool (i.e., a temporary carbon pool reserving photosynthetic compounds before allocations for new tissue production) was identified as a useful proxy variable of tree carbon starvation caused by reduction of gross primary production (GPP) and/or increase of maintenance respiration (Rm). Temporal Cpool variation agreed well with timings of pine tree diebacks for both sites. Though water stress was important, winter- and spring-time warmer temperature also played critical roles in reduction of Cpool, especially for the cool-and-wet Uljin. Shallow soil depth intensified the drought effect, which was, however, marginal for soil depth shallower than 0.5 m. Our modeling analysis implicates seasonal drought and warmer climate can intensify vulnerability of ENF dieback in Korea, especially for shallower soils, in which multi-year continued stress is of concern more than short-term episodic stress.

• Journal of the Korean earth science society
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• v.30 no.2
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• pp.247-256
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• 2009

Characteristics of hydrography and tidal currents were investigated in Hampyung Bay through in situ CTD data, tidal currents and elevations. According to the seasonal weather variability, hydrography showed the lower density with high temperature and low salinity in summer and the higher density with low temperature and high salinity in winter. In particular, the thermal structure like a tidal front was formed along the central channel at the neap tide of summer. The critical value of the parameter $SH(=log_{10}(H/U^3)$ where H is depth and U is $M_2$ tidal current amplitude) representing the formation position of tidal front was estimated from 2.4 to 3.5. In addition, the potential energy anomaly $({\phi})$ was ranged between 0.985 and 6.998 Joule/$m^3$, which gradually increased from the mouth into the inner bay. This front may be caused by the unique topography with wide tidal flat and the local difference of tidal current strength. The observed tidal currents at the mouth of bay showed that the ebb time was shorter than the flood time with the increase of depth. This asymmetric ebb-tide dominance is interpreted as a result of tidal distortion by the development of a shallow-water-constituent in Hampyung Bay with a wide macro-tidal flat.

• Journal of the Korean earth science society
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• v.29 no.3
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• pp.280-289
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• 2008

An extensive set of both in-situ and satellite data regarding oceanic sea surface temperatures in Northeast Asian seas, collected over a 10-year period, was collocated and surveyed to assess the accuracy of satellite-observed sea surface temperatures (SST) and investigate the characteristics of satellite measured SST errors. This was done by subtracting insitu SST measurements from multi-channel SST (MCSST) measurements. 845 pieces of collocated data revealed that MCSST measurements had a root-mean-square error of about 0.89$^{\circ}C$ and a bias error of about 0.18$^{\circ}C$. The SST errors revealed a large latitudinal dependency with a range of $\pm3^{\circ}C$ around 40$^{\circ}N$, which was related to high spatial and temporal variability from smaller eddies, oceanic currents, and thermal fronts at higher latitudes. The MCSST measurements tended to be underestimated in winter and overestimated in summer when compared to in-situ measurements. This seasonal dependency was discovered from shipboard and moored buoy measurements, not satellite-tracked surface drifters, and revealed the existence of a strong vertical temperature gradient within a few meters of the upper ocean. This study emphasizes the need for an effort to consider and correct the significant skin-bulk SST difference which arises when calculating SST from satellite data.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.4
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• pp.221-232
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• 2009

The geographical distribution of freeze risk determines the latitudinal and altitudinal limits and the maximum acreage suitable for fruit production. Any changes in its pattern can affect the policy for climate change adaptation in fruit industry. High-definition digital maps for such applications are not available yet due to uncertainty in the combined responses of temperature and dormancy depth under the future climate scenarios. We applied an empirical freeze risk index, which was derived from the combination of the dormancy depth and threshold temperature inducing freeze damage to dormant buds of 'Changhowon Hwangdo' peach trees, to the high-definition digital climate maps prepared for the current (1971-2000), the near future (2011-2040) and the far future (2071-2100) climate scenarios. According to the geospatial analysis at a landscape scale, both the safe and risky areas will be expanded in the future and some of the major peach cultivation areas may encounter difficulty in safe overwintering due to weakening cold tolerance resulting from insufficient chilling. Our test of this method for the two counties representing the major peach cultivation areas in South Korea demonstrated that the migration of risky areas could be detected at a sub-grid scale. The method presented in this study can contribute significantly to climate change adaptation planning in agriculture as a decision aids tool.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.2
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• pp.47-56
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• 2020

Decline of pine forests happens in Korea due to various disturbances such as insect pests, forest fires and extreme climate, which may further continue with ongoing climate change. For conserving and reestablishing pine forests, understanding climate-induced future shifts of pine tree distribution is a critical concern. This study predicts future geographical distribution of Pinus densiflora, using Maximum Entropy Model (MaxEnt). Input data of the model are locations of pine tree stands and their environmental variables such as climate were prepared for the model inputs. Alternative future projections for P. densiflora distribution were conducted with RCP 4.5 and RCP 8.5 climate change scenarios. As results, the future distribution of P. densiflora steadily decreased under both scenarios. In the case of RCP 8.5, the areal reductions amounted to 11.1% and 18.7% in 2050s and 2070s, respectively. In 2070s, P. densiflora mainly remained in Kangwon and Gyeongsang Provinces. Changes in temperature seasonality and warming winter temperature contributed primarily for the decline of P. densiflora., in which altitude also exerted a critical role in determining its future distribution geographic vulnerability. The results of this study highlighted the temporal and spatial contexts of P. densiflora decline in Korea that provides useful ecological information for developing sound management practices of pine forests.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.69-76
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• 2008

Three failure cases of CNG composite vessels were reported since after January 2005. The 1st and 2nd accidents were indebted to vessel defect and installation mistake. The 3rd was caused by gas leak at pipe connections. In this paper various aspects were studied based on information of the three failure analysis, which must be improved for better safety of the CNG bus system. Overpressure region caused by vessel explosion was theoretically predicted and also assessed by PHAST program. Explosion of 120 l vessel under 20 MPa is equivalent to 1.2 kg TNT explosion. The predicted value by PHAST was more serious than theoretical one. However, actual consequence of explosion was much less than both of the predicted consequences. Since the CNG vessel was designed by the performance based design methodology, it is difficult to verify whether the required process and tests were properly conducted or not after production. If material toughness is not enough, the vessel should be weak in brittle fracture at early in the morning of winter season since the metal temperature can be lower than the transition temperature. If autofrettage pressure is not correct, fatigue failure due to tensile stress during repeated charging is possible. One positive aspect is that fire did not ocurred after vessel failure. This may be indebted to fast diffusion of natural gas which hindered starting fire.

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.4
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• pp.703-713
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• 2021

This study was to investigate the thermal insulation of clothing ensembles, including padded jackets with two different filling types. Thermal insulation of the ensemble was measured using a thermal manikin in four conditions (10℃, 30% RH and 20℃, 50% RH with an air velocity of less than 0.15 m·s^-1 and 1.5 m·s^-1). Ten males participated at 10℃ and 30% RH with an air velocity of less than 0.15 m·s^-1 and 1.5 m·s^-1. The results showed that the polyester ensemble was warmer than a goose down ensemble in 0.15 m·s^-1 conditions and the goose down ensemble had greater thermal insulation than the polyester ensemble at an air velocity of 1.5 m·s^-1. Thermal insulation was reduced 5-7% when temperature decreased 10℃ and reduced 40-50% when air velocity reached 1.5 m·s^-1 for both ensembles. Thermal insulation of the ensemble in human trials decreased more than a thermal manikin at 10℃, 30% RH with an air velocity of 1.5 m·s^-1. Lower temperatures and human trials were effective in identifying the properties of the thermal insulation by filling types even though there were restrictions on the general application because of two types of a clothing ensemble.