Earticle

강원도 고성군에 있는 운봉산은 화강암 산지 사이에 단독으로 떨어져 있는 화산체로 경관이 매우 독특하다. 현무암 거력으로 구성된 애추와 암괴류가 일부 사면을 덮고 있다. 지질학적 측면에서 이 산의 특징은 비교적 상세히 조사되었다. 하지만, 암괴 지형의 전반적인 분포 패턴이나 발달과정은 잘 알려지지 않았다. 이 연구는 암괴 지형에 대한 지도화, 사면의 형태적 특성 분석, 암괴에 대한 야외조사를 통해 운봉산의 암괴 지형을 분류하고자 하였다. 노출 암괴는 산의 서사면에 집중적으로 분포하고 동사면에 는 거의 분포하지 않는 특징이 있다. 야외조사 결과, 암괴는 모두 주상절리가 발달한 현무암이었으며, 해발고도 및 경사에 따라서 장축방향성이 나타났다. 수치고도모형에 대한 지형위치지수(TPI) 및 사면분석 결과는 암괴류가 주로 계곡을 따라 분포하고 애추는 가파른 능선이나 현무암 단애 하부에 분포함을 보여주었다. 사면 지형을 분류한 결과, 산의 중심으로부터의 거리에 따라, 평탄한 산정부, 현무암 단애, 애추, 암괴류가 차례로 나타난다는 것을 확인하였다. 운봉산의 암괴 지형은 화산체의 사면 후퇴로 발생하는 사면발달과정을 잘 보여준다.

Unbongsan Mountain is a volcanic edifice with a unique landscape, which is located alone between granite mountains in Goseong-gun, Gangwon-do. The slopes of the mountain are partially covered with talus and block streams consisting of large basalt bouders. The geological features of this mountain have been investigated in detail. However, their overall distribution patterns and development processes are not well known. This study aims to classify these bouldery landforms through mapping the location of basalt blocks, the analysis of the morphological characteristics of the slope, and field surveys on the large boulders. The exposed boulders are concentrated in the western valleys of the mountains and are rarely found in the eastern slopes. Field data show that all the boulders are composed of basalt rocks with columnar joints, and that there is a long-axis isotropy related to the elevation and gradient of slope. In addition, the result of TPI and slope analysis for DEM indicate that block stream was mainly distributed along the valley, and the talus appeared in the steep ridge and the lower part of the cliffs. The slope classification indicates that flat mountain tops, basalt cliffs, talus, and block streams develop in sequence, as the distance from the center of the mountain increases. The bouldery landforms of Unbongsan Mountain illustrate the process of slope change that appears as a slope retreat in a volcanic edifice.

This paper proposes three one-time password (OTP) generation methods suitable for firmware OTPs, one of the most representative methods for addressing the rapidly growing demand for user authentication in online services, based on stream and block ciphers. The first method is a stream cipher-based approach consisting of a 127-bit linear feedback shift register (LFSR) and exclusive-OR (XOR) operators. The OTP output bits are determined using a bit-position selection derived from the digits of  . The second method is a block cipherbased approach employing triple data encryption standard (TDES). Part of the output bits are used as the OTP output and the remaining bits are fed back to the input through an output feedback (OFB) mode. The third method adopts advanced encryption standard (AES) as the block cipher, using a portion of the output bits as the OTP output and feeding back a subset of the remaining bits to the input. All methods generate initial values through key-based random number generation applying message authentication code (MAC). The proposed methods are implemented on an Arduino platform as firmware-based OTP generators. Experimental results demonstrate that the proposed methods offer strong security properties and are suitable for firmwarebased OTP generation. In addition, the LFSR-based method shows good performance in the NIST SP 800-22 randomness tests.

This study analyzed the relativity between block stream and talus distributions by employing a likelihood ratio approach. Possible distribution sites for each debris slope landform were extracted by applying a spatial integration model, in which we combined fuzzy set model, Bayesian predictive model, and logistic regression model. Moreover, to verify model performance, a success rate curve was prepared by crossvalidation. The results showed that elevation, slope, curvature, topographic wetness index, geology, soil drainage, and soil depth were closely related to the debris slope landform sites. In addition, all spatial integration models displayed an accuracy of over 90%. The accuracy of the distribution potential area map of the block stream was highest in the logistic regression model (93.79%). Eventually, the accuracy of the distribution potential area map of the talus was also highest in the logistic regression model (97.02%). We expect that the present results will provide essential data and propose methodologies to improve the performance of efficient and systematic micro-landform studies. Moreover, our research will potentially help to enhance field research and topographic resource management.

The main objective of this paper is to classify properties of the locational environment for each debris type by calculating likelihood ratio based on the correlation between the distributions for each type of debris landform. A total of 8 thematic maps, like as elevation, slope, aspect, curvature, topographic wetness index (TWI), soil drainage, geology, and landcover including with GIS spatial information generally used in this type of debris landform analysis. The results of this study showed that the block stream had a high likelihood ratio compared to talus in areas with relatively high elevation; and concerning slope, the block stream had a high likelihood ratio in a relatively low region than talus. Concerning aspect, a clear correlation could not be analyzed for each debris type, and concerning curvature, the block stream displayed a developed slope on the more concave valley than the talus. Analysis concerning TWI, the block stream displayed a higher likelihood ratio in wider sections than talus, and concerning soil drainage, the talus and block stream both displayed a high likelihood ratio in regions with well-drained soil. The talus displayed a high likelihood ratio in the order of metamorphic rocks, sedimentary rocks, and granite, while the block stream displayed a high likelihood ratio in the order of volcanic rocks, granite, and sedimentary rocks. In addition, concerning landcover, the likelihood ratio had the most concentrated distributed compared to natural bare land only concerning talus. Based on the likelihood ratio result, it can be used as basic data for extracting the possible areas of distribution for each debris type through the GIS spatial integration method.

Radon gas is one of the natural radioactive substances that appear in nature and known to cause lung cancer. Granite is widely distributed in Korea and a relatively high radon content has been detected through groundwater inspection. Previous studies have found that the radon content in the wind-hole area were higher than the safety level suggested as international safety standards. In this study, radon content of granite in Mt. Geumjeongsan and coastal areas comparatively investigated with the Mt. Jangsan area in Busan, where underground cold springs and rhyolite block streams are distributed. Radon contents in Mt. Jangsan are over 1,000Bq/m3, while those of Mt. Geumjeongsan and Seaside are lower than 200Bq/m3. Sedimentary rocks with high carbonate content showed low radon content. In particular, the radon content measured in two places in Jeongseon-gun, where ice is formed even in mid-summer was very low, confirming that the area with sedimentary rock high in carbonate content exhibited low radioactivity level.

MPEG-2 는 Layered Coding방식을 채택하여 하나의 base layer와 4개의 enhancement layer로 이루어져 있으나 동영상 재생을 위해 필요한 최소한의 layer인 base layer 만으로도 데이터 양이 많기 때문에 인터넷 환경에 적용하기가 어렵다. 이에 base layer를 다시 세분화된 layer로 나누기 위해 인코딩 중에는 또는 인코딩 결과로 만들어지는 MPEG-2 Video steam 의 하부 구조인 블록층에 존재하는 8$\times$8블록의 AC 계수들을 layering한다. Layered된 base layer의 데이터는 통신망 및 단말기의 QoS에 따라 서로 다른 전송 채널을 통해 서버에서 클라이언트 디코더로 전송된 후 디코더에 실시간적으로 병합한 후 재생된다. 본 논문에서 제안하는 기법을 이용하여 기존에 encoding MPEG-2 Video steam의 AC계수를 layering할 경우에 QoS에 따라 가변적으로 데이터 양을 서버 쪽에서 조절할 수 있었고, 통신 선로 상에서 이동하는 데이터 양의 원래의 MPEG-2 Video steam 을 이용했을 때보다 인코딩 중에 블록을 변환하면 51% 정도 감소하고 인코딩 되어진 데이터를 이용했을 경우에는25%정도 감소하는 것을 알 수 있었다.