High voltage impulse (HVI) has been gained attention as an alternative technique that could control the CaCO3 scale problems encountered in water main, pipe, cooling tower and heat exchanger vessels. The aim of this study was to investigate the effect of electric field (E) and contact time (t) of HVI on reduction of Ca2+ concentration at two different temperatures of 25℃ and 60℃. A kinetic model on the effect of E and t was investigated too. As the E and t increased, the Ca2+ concentration decreased more than that of the control (= no HVI). The Ca2+ concentration decreased up to 81% at 15 kV/cm at 60℃, which was nearly 2 times greater than the control. With these experimental data-set of reduction of Ca2+ concentration under different E and t, the kinetic model was developed. The relationship between E and t required to reduce the concentration of Ca2+ by 30% was modeled at each temperature. The empirical model equations were; E0.83· t = 60.3 at 25℃ and E0.08· t = 1.1 at 60℃. These equations state the products of En and t is always constant, which means that the required contact time can be reduced in accordance with the increment of E and vice versa.

2000년대 중반부터 본격적으로 북한에 유입된 남한 미디어는 북한 사회변화의 주요한 지표가 된다. 국내 언론 보도 및 탈북민들의 증언을 통해 폐쇄된 북한 사회에서도 남한 영상물을 시청한다는 사실이 확인되면서 이 분야에 관한 연구가 활발히 이루어지고 있다. 문제는 북한 내외 부정보 확산 현상을 어떻게 해석하느냐의 여부다. 북한에서 외부정보를 접한 북한 주민의 의식과 사회현상 더 나아가 북한체제 변화에 어떠한 영향을 미치는가의 문제이다. 본 연구는 김정은 시대에 한국에 입국한 탈북민을 대상으로 설문조사를 통해 북한 내 외부정보 실태를 파악하고, 이들의 인식변화 과정을 분석한다. 의식변화 추이는 남한과 남한 사람, 북한 정권에 대한 인식, 민주주의와 인권 등의 세부항목별로 조사가 이루어졌다. 북한에서의 남한 미디어 이용실태를 바탕으로 향후 남북한 통일과정에서 북한주민의 ‘마음 얻기’를 위한 미디어 활용방안을 모색한다.

본 연구에서는 CH4/CO2 혼합가스에서 CO2 분리를 위해 세라믹 중공사 접촉막 모듈(HFMC)을 이용하여 실험을 수행하였다. 고 내구성의 HFMC를 제작하기 위해, 고강도의 중공사막을 제조하여 평가하였다. 제조한 중공사막을 이용하여 HFMC를 제작하였고, 실험은 CH4/CO2 혼합 기체(30% CO2, CH4 balance)와 monoethanolamine (MEA)를 사용하였다. HFMC 운전 중 기체와 흡수제의 압력이 CO2 제거 효율에 어떠한 영향을 주는지 평가하였다. CO2 제거 효율은 기체압력이 증가함에 따라 같이 상승하였으며, CO2 흡수 flux 또한 액체유량과 함께 증가하는 추세를 보였다. 또한 CO2 흡수율이 40% 이하일 때 는 흡수제가 아래쪽에서 들어가는 향류형태인 LTS-1이 흡수제가 위쪽에서 들어가는 향류형태인 LTS-2보다 CO2 제거 성능 이 높았으며, 흡수율이 40% 이상일 때는 LTS-2가 LTS-1보다 성능이 높았다.

This study aims to categorize research achievements about language contact based on the papers in the Sociolinguistic Journal of Korea for the last thirty years into five sections, which include bilingualism and diglossia, pidgin and creole, various decision making under language contact situations, loan-words, and dialect contact. This study concludes by offering further research questions that need to be answered in the field of language contact. Early years of sociolinguistics has remained at a level of introducing language contact problems of Europe and Africa, Pacific and Atlantic equator region to the domestic academic circles. However, these achievements have turned out to be the foundation of research related to overseas Koreans bilingualism problem and various domestic language contact problems between Korean and foreign language. Until now, Korean sociolinguistics has mostly handled problems of bilingualism. However, since the early 21st century, the population of international marriage immigrants and foreign laborers has increased at a rapid rate, generating various language contact phenomena. Furthermore, with a recent globalization wave, many foreign languages are more widely used in Korea. In such a flow, it is evident that the Korean society will go through various language contact between Korean and foreign languages. Therefore, systematic and aggressive research on multi-culture family bilingualism, code-switching of Korean speakers, loan-words situation, and the problem of contact between standard language and dialect is needed in the Korean sociolinguistic field.

본 연구에서는 세라믹 중공사 접촉막 모듈을 이용하여 CH4/CO2 혼합가스에서 CO2 분리 실험을 수행하였다. 높은 성능의 접촉막 모듈을 제작하기 위해 고투과성 중공사막의 제조 실험을 진행하였으며, 제조한 중공사막은 N2 기체투과실험을 통해 투과 성능을 평가하였다. 최종적으로 고투과도 중공사막을 이용하여 CH4/CO2 혼합 기체 분리를 위한 Hollow fiber membrane contactor (HFMC)를 제작하였다. 실험에는 CH4/CO2 혼합 기체(34.5% CO2, CH4 balance)와 monoethanolamine (MEA) 를 사용하였으며, CO2 제거 효율이 흡수제의 유량에 따라 어떠한 영향을 받는지 평가하였다. CO2 제거 효율은 액체유량이 증가함에 따라 같이 상승하였으며, CO2 흡수 flux 또한 액체유량과 함께 증가하는 결과를 보였다.

In recent years, studies on various 3D scanner applications, including those on quality control and reverse engineering, have been conducted in the shipbuilding industry. Appropriate scanner selection, scanning environment setting by targets, and data postprocessing are essential for effective 3D scanning projects for small crafts. In this study, a non-contact handheld-type 3D scanner was used for molds and hull products for the 10– 30-ft class of small crafts. Small crafts have fewer geometric features and several glare surfaces; thus, anti-glare and texture feature addition preprocessing is critical. The 3D scanning results are used for geometry quality control of single panels and curved surfaces in craft hulls. Consequently, international rule-based weight estimation calculation sheets have been developed and applied for product weight quality control.

본 연구에서는 건조 고춧가루의 가공 및 저장라인에서 구리의 이용가능성을 조사하였다. 구리와 스테인리스강 표면과의 접촉을 통한 고춧가루의 색도 변화를 평가한 결과, 55oC에서 2시간 구리 판에 처리한 시료의 명도가 다소 증가하였다. 구리와 스테인리스강 접촉에 의한 고춧가루 내 미생물 저해는 중온성의 호기성 세균보다 곰팡이 및 효모의 저해에 더 효과적이었고, 55oC에서 2시간 구리 접촉에 의해 곰팡이와 효모의 수는 0.64 log 감소하여 유의적인 효과를 나타내었다. 산화방지 활성은 구리와 스테인리스 강 접촉 고춧가루의 DPPH 라디칼 소거활성은 감소한 반면 ABTS 라디칼 소거활성은 증가하였다. 본 연구는 구리 또는 구리와 스테인리스강 등의 합금을 이용하여 고춧가 루를 포함한 다양한 분말 식품의 가공 및 저장 과정에 활용할 수 있는 가능성을 제시하고 있다.

This study was aimed to examine inorganic fouling and fouling reduction method in direct contact membrane distillation(DCMD) process. Synthetic seawater of NaCl solution with CaCO3 and CaSO4 was used for this purpose. It was found in this study that both CaCO3 and CaSO4 precipitates formed at the membrane surface. More fouling was observed with CaSO4(anhydrite) and CaSO4･0.5H2O(bassanite) than CaSO4･2H2O(gypsum). CaCO3 and gypsum were detected at the membrane surface when concentrates of SWRO(seawater reverse osmosis) were treated by the DCMD process, while gypsum was found with MED(multi effect distillation) concentrates. Air backwash(inside to out) was found more effective in fouling reduction than air scouring.

PURPOSES : The feasibilities of cohesive elastoplastic contact model and discrete element method (DEM) for asphalt concrete mixture compaction process were evaluated. METHODS : The contact models that were used to simulate the dynamic behavior of construction materials were reviewed. The characteristics of cohesive elastoplastic models were discussed from the perspective of integration with existing contact models. Two asphalt mixtures that were fabricated with specific aggregate gradations and binder contents were compacted according to the Superpave gyratory compaction specification. The parameters for the model were determined via trial-and-error method. The heights of the specimens were plotted with respect to number of gyrations. The results of the laboratory tests were compared to those of numerical simulations. The displacement of particles in asphalt mixture specimen was also visualized to understand the effect of gyratory compaction on asphalt mixture specimen. RESULTS : The DEM model exhibited a significant friction coefficient dependency on compaction degree and slop. The DEM model with parameters determined through trial and error demonstrated reasonable simulation results in terms of specimen height at a gyration number. CONCLUSIONS: Even though a little discrepancy was observed between the results of the experimental test and numerical simulation, a combination of DEM with cohesive elastoplastic contact model seems to be applicable for the simulation of asphalt mixture compaction in laboratory. However, the model needs to be enhanced to be used for more realistic compaction processes, including heat transfer, phase change, and vibratory loading.