PURPOSES : A pilot experimental study on the formation of fine particulate matter through photochemical reactions using precursor gas species (volatile organic compounds (VOCs), NH3, SO2, and NOx) was conducted to evaluate the large-scale environment chamber for investigating the pathway of aerosol formation and the subsequent assessment techniques used for reducing fine particulate matter. Two small-scale environment chambers (one experimental group and one control group), each with a width, depth, and height of 3 m, 2 m, and 2.3 m, respectively, were constructed using ethylene tetrafluoroethylene (ETFE) films. METHODS : The initial conditions of the fine particles and precursor gases (NOx and VOCs) for the small-scale environment chamber were set up by injecting diesel vehicle exhaust. NH3 and H2O2 were added to the small-scale environment chamber for the photochemical reaction to form organic and inorganic aerosols. The gas phase of the VOCs and the chemical compositions of aerosols were investigated using a proton transfer reaction time-of-flight mass spectrometer and the aerodyne high-resolution time-of-flight aerosol mass spectrometer at 1 and 10 s time resolutions, respectively. Gas phases of NO and NO2 were measured using Serinus 40 NOx at a 20 s time resolution. RESULTS : The small-scale environment chambers built using ETFE films were proved to supply sufficient natural sunlight for the photochemical reaction in the environment chambers at an average of approximately 89% natural sunlight transmission at 300–1000 nm. When the intermediates of NH3 and H2O2 for the atmospheric chemical reaction were injected for the initial condition of the small-scale environment chamber, nitrate and ammonium in the experimental group increased to 4747% and 1837%, respectively, compared to the initial concentrations (5.4 μg/m3 of nitrate and 5.2 μg/m3 of ammonium), indicating the formation of secondary inorganic aerosols of ammonium nitrate (NH4NO3). This implies that it is necessary to inject intermediates (NH3 and H2O2) for the formation of fine particulate matter when simulating the atmospheric photochemical reaction for assessing the environment chamber. CONCLUSIONS : This study has shown that small-scale environment chambers can simulate the atmospheric photochemical reaction for the reduction of fine particulate matter and the formation of the aerosol pathway. The results of this study can be applied to prevent time and economic losses that may be incurred in a full-scale environment chamber.

PURPOSES : This study analyzes the characteristics of generated fine particulate matter (PM2.5) and nitrogen oxide (NOX) at roadsides using a statistical method, namely, a generalized linear model (GLM). The study also investigates the applicability and capability of a machine learning methods such as a generalized regression neural network (GRNN) for predicting PM2.5 and NOX generations. METHODS : To analyze the characteristics of PM2.5 and NOX generations at roadsides, data acquisition was conducted in a specific segment of roads, and PM2.5 and NOX prediction models were estimated using GLM. In addition, to investigate the applicability and capability of a machine learning methods, PM2.5 and NOX prediction models were estimated using a GRNN and were compared with models employing previously estimated GLMs using r-square, mean absolute deviation (MAD), mean absolute percentage error (MAPE), and root mean square error (RMSE) as parameters. RESULTS : Results revealed that relative humidity, wind speed, and traffic volume were significant for both PM2.5 and NOX prediction models based on estimated models from a GLM. In addition, to compare the applicability and capability of the GLM and GRNN models (i.e., PM2.5 and NOX prediction models), the GRNN model of PM2.5 and NOX prediction was found to yield better statistical significance for r-square, MAD, MAPE, and RMSE as compared with the same parameters used in the GLM. CONCLUSIONS : Analytical results indicated that a higher relative humidity and traffic volume could lead to higher PM2.5 and NOX concentrations. By contrast, lower wind speed could affect higher PM2.5 and NOX concentrations at roadsides. In addition, based on a comparison of two statistical methods (i.e., GLM and GRNN models used to estimate PM2.5 and NOX), GRNN model yielded better statistical significance as compared with GLM.

PURPOSES : The purpose of this study is to evaluate the performance characteristics of stone mastic asphalt (SMA) pavement by comparison with polymer modified asphalt (PMA) pavement and conventional asphalt pavement, to check the performance characteristics according to the pavement type, pavement materials, traffic volume, and environmental factors and to analyze the quality variation characteristics according to the pavement materials using data extracted from the database of the expressway long-term pavement performance. METHODS : Approximately 10% outlier data of pavement performance data were excluded in order to increase the reliability of the analysis results before evaluating the asphalt pavement performance. The performance model was developed through linear regression analysis by setting the performance period as the independent variable and the highway pavement condition index (HPCI) as the dependent variable. Descriptive statistic analysis of HPCI using the static package for social science (SPSS) tool and the analysis of variance was performed to identify the quality variation characteristics according to the pavement materials. The amount of de-icing agent and traffic level of service were classified as two levels in order to check the influence of traffic volume and environmental factors on the performance characteristics of the asphalt pavement. RESULTS : The tentative pavement performance lives were calculated at 19.3 years for new the SMA pavement (GPS-2), 14.3 years for the SMA overlay on the asphalt pavement (GPS-6), and 10.3 years for the SMA overlay on the concrete pavement (GPS-7). In case of the asphalt overlay, the tentative performance lives were calculated at 8.2 years for the PMA overlay on the asphalt pavement (GPS-6), 7.2 years for the PMA overlay on the concrete pavement (GPS-7), 7.2 years for the conventional asphalt overlay on the asphalt pavement (GPS-6), and 5.5 years for the conventional asphalt overlay on the concrete pavement (GPS-7). CONCLUSIONS : It was confirmed that the SMA pavement showed better performance and quality variation characteristics than the PMA and conventional asphalt pavement. The performance characteristics of the asphalt pavement (GPS-2) was better than the asphalt overlay pavement, and the asphalt overlay on the asphalt pavement (GPS-6) had better performance characteristics than the asphalt overlay on the concrete pavement (GPS-7). It was observed that the asphalt overlay on the asphalt pavement (GPS-6) was strongly influenced by the traffic volume and the asphalt overlay on concrete pavement (GPS-7) was strongly influenced by the traffic volume and de-icing agent.

This study was a qualitative investigation into hemodialysis patients' dietary practices. The purpose of this study was to explore the obstacles and requirements to maintain a recommended diet therapy in hemodialysis patients. Five patients undergoing hemodialysis in the renal chamber of the general hospital were interviewed individually. The interviews were based on an interview guide and analyzed by Giorgi’s method of analysis. As a result of this study, five elemental factors and 12 subelemental factors were derived. Derived elements were “difficulty in dietary guidelines”, “recognizing necessity of diet therapy”, “awareness of importance of diet”, “difficulty practicing diet therapy”, and “looking for ways to practice diet therapy”. Patients not only felt difficulties in practicing dietary guidelines but also recognized the need and importance of diet therapy. Patients seemed to have difficulty practicing meal therapy and eating with their families or others. They were also stressed by the limited selection of dietary components and rapid dietary changes before and after dialysis. However, patients showed a willingness to implement dietary management to improve their quality of life and to practice dietary therapy. In order to improve the practice of dietary management in hemodialysis patients, nutritional education should be focused on long-term dietary habits through continuous education and monitoring, not just one-off education. Moreover, patients should be educated that adherence to dietary control may be less burdensome on their families.

본 연구는 침입종 사향쥐의 국내 자연생태계 정착 여부를 확인하였다. 아울러 관리전략 수립과 현장 관리에 필수적인 관리대상지역과 기초적인 행동특성 정보, 서식지 이용에 관한 자료를 제공하고자 하였다. 이를 위해 해외의 사향쥐 관리 동향을 파악하여 정착 단계에 따른 관리 방향을 검토하였다. 그리고 국내 72개 사육농가의 위치정보를 확보하였고, 실태조사를 통해 경기도, 충청남도, 경상북도, 세종특별자치시 소재 5개 지역을 자연 유출 가능성이 높은 지역으로 제시하였다. 또한, 2016년부터 2018년까지 3년간 동일 지점에 서식하는 개체를 모니터링하였다. 2018년 모니터링 지역에서 포획한 개체의 연령이 1.2년생으로 확인되었으며, 2012년 이후 해당지역에 추가적인 개체 보충이 없었다는 사실에 근거하여 국내 자연생태계에 사향쥐가 정착한 것으로 판단하였다. 국내 자연에 정착한 사향쥐는 0.0027 km2 (MCP 95%)의 작은 행동권을 나타내었으며, 봄철과 가을철 규칙적인 이동성을 보이는 것으로 나타났다. 사향쥐의 서식이 관찰된 지역은 서식환경의 교란이 높게 발생한 지역이었으며, 사향쥐의 흔적 출현 빈도는 부엽식물과 부유식물의 생육이 왕성한 개방수역과 개체의 은신처로 활용 가능한 습생목본 식생유형에서 높게 확인되어 이들의 생태적 특성과 섭식 습성이 그대로 반영되었다. 국제적인 침입종 사향쥐가 국내 생태계에 정착하였고, 향후 확산이 우려되는 만큼 정부 차원의 선제적 대응과 과학적 관리를 위한 필수 자료 구축이 검토될 필요가 있다

In this study, a survey was conducted among university students (119 men and 134 women) in Chungbuk province using questionnaires to investigate the variables and eating patterns related to the use of food delivery apps. A survey was conducted from March 22, 2019 to April 3, 2019. Of the total respondents, 77.2% reported that they had ordered food at least once using food delivery apps on smartphones. Further, 63.3% of the total subjects had ordered food delivery through smartphone apps once or twice a month, and the most preferred cuisine for food delivery was fast food, followed by Bunsik (Korean street food/snack), western food, and Chinese food. The average satisfaction scorefor food delivery apps was 3.8 points, and the satisfaction score was the highest with the convenient ordering process (4.0), followed by good taste (3.9) and good portion (3.8). The subjects who used smartphone food delivery apps three times or more a month showed a significantly higher frequency of instant food intake (p=0.0132), dining out (p=0.0282), and late-night eating (p=0.0047) than the subjects who ordered food using delivery apps less than three times a month. In conclusion, these study results may be applied as baseline data for dietary education among university students.

고지방식이에 의해 유도한 비만모델동물에서 지장김치의 혈액 중 유해 지질 감소, 항비만 효능 및 그 작용 메카니즘을 조사하였다. 4개의 처리구는 CD(일반식이를 섭취한 정상 대조구, chow diet as normal control), HFD(고지방식이를 섭취한 비만 대조구, high fat diet as obesity), HFDCK(고지방식이+일반김치 추출물 투여구), HFDJK(고지방식이+지장김치 추출물 투여구)로 구분하여 김치추출물을 28일 동안 경구투여 하였다. 체중, 간 및 지방조직 무게는 비만모델동물에서 HFDJK가 HFDCK에 비해서 낮았다(p<0.05). 혈액 중성지방, 총콜레스테롤, LDL-C, 혈당은 HFD와 비교할 때 CD, HFDJK, HFDCK의 순서대로 낮았으며 HFDJK는 HFDCK에 비해 낮았다(p<0.05). 간 및 지방세포의 크기는 HFD, HFDCK, HFDJK의 순서대로 증가하였으며 HFDJK는 HFDCK에 비해서 크게 낮았다(p<0.05). 결과는 비만모델동물에서 지장김치의 섭취가 일반김치에 비해서 혈액 지질과 혈당을 낮추고 지방세포의 크기를 줄여줌으로써 항비만 효능을 갖는다는 점을 나타낸다.

Two experiments were conducted to determine how much sodium in food could be detected using a salinity meter. First, the salinity of mixed solutions of 0 to 6% sugar, 0 to 5% oil, and 0 to 6.4% MSG in a 1% NaCl solution was measured using a salinity meter and a Mohr titration method, and the results were compared with the calculated sodium expectations. As a result, the sodium contents of the sugar solutions and MSG solutions measured using a salinity meter were lower than the expected concentrations at 2% or more and 0.8% or more, respectively (p<0.05). The salinity of the 18 HMR products was measured in the same way, and the results were then compared with the sodium contents of the nutrition facts. The average sodium content of all products measured using the salinity meter and Mohr method was 1.12 times and 1.06 times the sodium content of the nutrition facts, respectively. On the other hand, the differences between the products were significant. The correlation coefficients between the nutrition facts and salinity meter, the nutrition facts and the Mohr method, and the salinity meter and Mohr method were 0.885, 0.920, and 0.950, respectively (p<0.01).

한반도 북부 지역에 적응하는 옥수수 품종 개발의 기초연구의 일환으로 2017~2018년 중국 요녕성 동항과 연변주 용정에서 18 품종/교잡계를 파종기, 재식거리 및 시비량 등 관행에 따라 재배하여 출사기 성숙기 반응 및 수량성을 조사하였다. 1. 지역 간의 출사까지의 적산온도 차이가 출사일수의 변이 보다 적으며, 출사일수 차이가 10일 이상인 품종/교잡계는 다청옥, 강다옥, 14GS19/14GS11이었다. 출사일수의 연차변이가 적은 반면 출사까지 적산온도가 큰 경향을 보였다. 2. 동항이나 용정의 적산온도는 북한의 옥수수 숙기 분류기 준에 중간늦종 범위를 벗어나는 늦종 그룹으로 분류할 수 있었다. 용정에서는 북한 성수군 기준의 늦종 재배 가능하며, 동항은 북한의 수풍, 회천, 신포, 양덕, 평강을 잇는 지역에 해당한다. 3. 평균 수량이 10a 당 1,000 kg 이상인 품종은 신황옥 (1,076 kg), 황다옥(1,023 kg), 그리고 중국 비교품종 Xianyu335, Fulai818도 각각 1,013 kg과 1,038 kg이었다. 18개 품종/교잡 계의 대부분이 중간늦종~늦종 군에 분류되었다. 18개 품종/교 잡계의 대부분이 중간늦종~~늦종 군에 분류되었다. 4. 북한의 각 지역별 재배 가능한 성숙군은, 중산지 혜산은 중간종, 북부 선봉은 중간종~중간늦종, 북부 산간인 중강과 동해안 북부 청진지방은 중간늦종~늦종 재배가능지이며, 그 외 지역은 모두 3,000oC 이상으로 늦종 재배에 충분한 적산온도 를 보였다. 북부산간 고지대인 삼지연, 풍산, 장진은 적산온도 2,000oC 이하 지역으로 옥수수 재배가 어려운 지역으로 나타 났다.

PURPOSES: The objective of this study is to evaluate the shear and tensile strength properties of adhesive road studs in asphalt and concrete pavements. METHODS: The 300 mm×300 mm×50 mm rectangular specimens were fabricated using asphalt and concrete mixture for installation of road studs. Four 140-mm-radius circular areas were milled on each specimen with depth of 5 mm to install the adhesive road studs. About 100 g of thermal melting adhesive was applied on the milled area, and then the road stud was bonded onto the surface of the asphalt and concrete mixture. Direct shear testing was conducted at a speed of 5 mm/min on the interface between road stud and asphalt and concrete materials. Tensile strength testing was also conducted on the prepared specimens by applying load with increase of 50 kPa per second. These tests were performed not only in dry condition but also in wet condition to determine the effect of moisture on the shear and tensile strengths. RESULTS : According to the shear testing results, the average shear strength of asphalt samples in dry and wet conditions are 0.509 and 0.234 MPa, respectively. From this testing, the shear strength of wet sample was found to be decreased by 50% with respect to that of the dry sample. Similar trends can be observed on the concrete samples. The average tensile strength of asphalt samples was 0.187 MPa at 1.5 mm of displacement in dry condition. The concrete sample has a 0.222 MPa average tensile strength, which is slightly higher than that of the asphalt sample because of the rough surface characteristics of the concrete sample. CONCLUSIONS: It is determined from this study that the shear and tensile strengths of road stud bonded on the surface of asphalt mixture are slightly lower than those on concrete samples. Regardless of the pavement type, the wet conditioning of the sample can decrease the shear and tensile strength by 50% those of the dry sample. In the future, the quality improvement of adhesive and increase of specific surface area should be considered to improve the bonding property between road stud and pavement surface.

PURPOSES: The purpose of this study is to analyze characteristics of concentrations of fine particulate matter (PM2.5) among 3 different types of bus stops, specifically partially closed bus stop with front & back partition, partially closed bus stop with back partition, and bus stop with open space (referred to as bus stop types Ⅰ, Ⅱ, and Ⅲ, respectively) at urban roadside, using the Anderson-Darling test as statistical method. METHODS: For the purpose of this study, first of all, data on concentrations of PM2.5 on the 3 types of bus stops at urban roadside were acquired for certain days, with different levels of air quality index (AQI). Secondly, this study accomplished the data processing of removing outliers from acquired data, and the Anderson-Darling test was conducted to estimate probabilities of occurrence for concentrations of PM2.5 in the 3 types of bus stops. RESULTS : The average concentrations of PM2.5 for AQI‘ Very High’for bus stop types Ⅰ, Ⅱand Ⅲare 46-179㎍/m3, 66-194㎍/m3, 42- 134㎍/m3, respectively, and for AQI ‘High’for bus stop typesⅠ, Ⅱ and Ⅲ are 16-71㎍/m3, 26-84㎍/m3, and 14-69㎍/m3, respectively. Furthermore, probabilities of occurrence for concentration levels of PM2.5 in AQI were estimated for given measurement dates using the Anderson-Darling test as statistical method. As a result, for AQI ‘Very High,’the probabilities of occurrence for concentration levels ‘Very High’and‘ High’were determined more likely to occur regardless of bus stop type. With respect to each type of bus stop, the probabilities of ‘Very High’for bus stop type Ⅱ were 93.37% and 98.92%, higher than for the other bus stop types. For AQI ‘High’the probabilities of occurrence for concentration levels‘ Good’were found to be very low, at 0.00% to 3.07%, and occurred mainly for‘ Moderate’and‘ High’in this study. In particular, the probabilities of occurrence for concentration level‘ High’for bus stop type Ⅱwere analyzed to be greater than 90%, compared to those for the other bus stop types. CONCLUSIONS: Based on the result of this study, when PM2.5 is analyzed on certain days, probabilities of occurrence for concentration levels in AQI should be considered for each type of bus stop.

경제 세계화의 지속적인 진전과 사회 경제의 급속한 발전으로 인해 기업의 경쟁은 더욱 치열해지고 기업 경쟁의 초점이 물리적 자본 경쟁에서 인적 자본 경쟁으로 점차 변화해 가고 있다. 인적자원의 질은 기업의 직무성과에 직접적으로 영향을 미치며 기업의 생존 및 발전과 밀접하게 관련되어 있다. 이에 따라 조직의 리더에 대한 기대는 더욱 높아졌다. 조직의 리더들은 높은 윤리적 수준을 바탕으로 구성원과 투명한 의사소통을 통해 동기부여하고, 자기 결정권을 높여주어 급변하는 새로운 환경에 잘 적응하도록 훈련시켜야 하며, 이를 통해 구성원의 직무성과를 높여주어, 지속적인 기업 성장을 가능하도록 해야 한다. 이런 측면에서 최근 진성리더십이 주목받고 있다. 특히, 현대사회는 조직의 규모가 커지고 복잡해짐으로써 조직 내 상호작용하는 과정에서 여러 가지 갈등상황이 발생하고 있다. 따라서 조직의 리더들은 이러한 갈등을 관리하거나 완화시키는 리더십을 발휘해야 한다. 본 연구는 조직 상황에서 상사의 진성리더십이 상사와 구성원 간 갈등에 어떤 영향을 미치는지, 그 영향으로 과업성과와 조직시민행동에 어떠한 변화를 주는지에 대해 실증적으로 살펴보고자 한다. 본 연구를 위해서 중국 기업의 직장인을 대상으로 약 1주간 설문조사가 실시되었으며 365부의 설문지를 배부하였다. 이 중 성실하지 않은 응답을 제외한 245부의 설문지를 분석하였다. 실증연구 결과는 다음과 같다. 첫째, 상사의 진성리더십은 갈등에 부적인(-) 영향을 미쳤다. 둘째, 갈등은 개인지향 조직시민행 동에는 부적인(-)인 영향을 미쳤지만, 과업성과와 조직지향 조직시민행동에는 유의미한 영향을 미치지 못하였다. 셋째, 갈등의 매개효과는 진성리더십과 개인지향 조직시민행동 간의 관계에서만 나타났다. 그 외 진성리더십과 과업성과 및 조직지향 조직시민행동 간의 관계에서는 매개효과가 나타나지 않았다. 지지되지 않은 가설에 대해서는 추가분석을 통해 그 이유를 살펴보았다. 그리고 연구의 요약과 함께, 시사점, 한계 및 향후연구방향을 제시하였다.

PURPOSES: In this study, a numerical parametric study was performed to evaluate the effect of angular velocity and weight of wheel, and density of road-bed particles on corrugation development. METHODS : Discrete element method coupled with rigid body dynamics was applied to simulate a wheel-running circular table with variations in independent parameters, such as wheel angular velocity, wheel weight, and particle density. The position profiles for travel distance from origin were compared and analyzed to confirm if the trend from numerical analysis agrees with the analytical solution. RESULTS: The angular velocity of the wheel exhibits a clear inverse relationship with the development of corrugation even though the weight of wheel does not demonstrate clear trends for both long-wave and short-wave corrugation. The density of road-bed particles is observed to have clear proportional effect on corrugation development. The movement of corrugation to the running direction, which was observed in previous research, is also observed for various conditions. CONCLUSIONS : The parametric study using discrete element method with rigid body dynamics clearly exhibits good agreement with analytical solution for initiation of corrugation. The coupled method is confirmed to supply additional information that cannot be delivered by analytical solution only.