Judul: Kondisi Oseanografi dan Kualitas Perairan Terhadap Status Ekosistem Terumbu Karang di Pesisir Barat Sumatera Utara
Abstrak: Ekosistem terumbu karang di pesisir barat Sumatera Utara telah mengalami penurunan persentase tutupannya selama dekade terakhir. Hal ini disebabkan oleh aktivitas nelayan menggunakan bahan peledak, kegiatan industri, pelayaran, serta faktor alam seperti tsunami pada tahun 2005. Penelitian ini bertujuan untuk melihat kondisi oseanografi dan kualitas perairan terhadap status ekosistem terumbu karang di pesisir barat Sumatera Utara. Penelitian ini menggunakan metode observasi lapang, analisis laboratorium, dan data reanalisis dari INDESO serta Marine Copernicus. Observasi lapang dilakukan pada 9 titik pengamatan, parameter yang diukur meliputi kedalaman perairan, suhu, salinitas, kecerahan, TSS, nutrien, arus, pH, DO, tipe substrat dan pengamatan ekosistem terumbu karang dengan metode Line Intersept Transect. Hasil penelitian menunjukan kondisi oseanografi perairan memiliki tunggang pasut kecil, berarus kuat, dan bergelombang tinggi yang sangat dipengaruhi oleh musim. Kualitas perairan tergolong sesuai dengan baku mutu KMLH No. 51 Tahun 2004 untuk biota di ekosistem terumbu karang. Data INDESO dan Marine Copernicus memiliki pola yang berkesesuaian dengan data lapang sehingga bisa dijadikan acuan dalam menggambarkan kondisi oseanografi dan kualitas perairan secara spasial dan temporal. Tutupan terumbu karang berkategori buruk hingga baik dengan persentase berkisar 0–55%. Bentuk pertumbuhan karang dominan massive dan encrusting yaitu bentuk yang kokoh sehingga mampu beradaptasi dengan lingkungan laut terbuka.
Keyword: Ekosistem Terumbu Karang, INDESO, Kualitas Perairan, Marine Copernicus, Oseanografi

Judul: Coral Reef Ecosystem Analysis Related With The Quality of Water in Labuan Waters, Pandeglang District, Banten
Abstrak: Terumbu karang merupakan ekosistem dengan kerentanan tinggi terhadap perubahan lingkungan perairan, dapat disebabkan faktor alami (autogenic) ataupun faktor manusia (anthropogenic). Penelitian ini dilakukan untuk menganalisis kondisi kualitas perairan serta keterkaiatannya dengan terumbu karang yang dilakukan pada 9 lokasi pengamatan kualitas air dan 4 lokasi pengamatan kondisi ekosistem terumbu karang di wilayah Labuan Banten. Penelitian ini diharapkan dapat menjadi acuan pengelolaan lingkungan wilayah perairan Labuan Banten, serta sebagai bahan dasar pengelolaan sumberdaya ekosistem pesisir khususnya ekosistem terumbu karang perairan Labuan Banten. Metode yang digunakan adalah metode survey, pengambilan data ekosistem terumbu karang dilakukan dengan metode Line Intercept Transect (LIT). Pengukuran kualitas air dilakukan dengan melakukan pengukuran parameter fisika perairan yang dilakukan secara insitu menggunakan water quality meter, dan parameter kimia air laut dengan identifikasi laboratorium. Tutupan substrat dasar ekosistem terumbu karang perairan Labuan Banten memiliki persentase karang keras 1,72% hingga 13,34%. Nilai persentase tutupan karang tersebut menggambarkan kondisi terumbu karang termasuk dalam kategori Rusak. Persentase tutupan substrat dasar berupa algae memiliki nilai tertinggi 54,08%. Nilai kualitas perairan secara umum dicirikan oleh nilai nitrat dan nilai COD dengan kondisi kualitas perairan yang sudah melebihi ambang batas. Keterkaitan kualitas air dengan ekosistem terumbu karang dicirikan dengan persentase Alga yang tinggi akibat tingginya nitrat, Keberadaan komunitas alga yang tinggi pada ekosistem terumbu karang menggambarkan bahwa adanya kompetisi ruang terhadap kondisi terumbu karang di Perairan Labuan Banten., Coral reefs ecosystems are highly vulnerability to the underwater environment changes, both caused by autogenic or anthropogenic. This study has been carried out at nine water quality observation locations and four observation locations for coral reef ecosystem conditions in the Labuan Banten region, to observe the water quality and its relation with coral reefs ecosystem. The outcome this research can be used as reference for environmental management in the waters of Labuan Banten, as well as a primary material for managing coastal ecosystem resources. This research utilise surveys methods, in which the coral cover data used Line Intercept Transect (LIT). Water quality measurements were carried out by measuring the physical parameters of the waters using a water quality meter and the chemical parameters by laboratory identification. The percentage value of coral cover describes the condition of coral reefs included in the damaged category. The percentage of base substrate cover in the form of algae has the highest value of 54.08%. The value of water quality is generally characterized by the value of nitrate and COD with water quality conditions that have exceeded the threshold. A high percentage of algae characterizes the relationship between water quality and coral reef ecosystems due to high nitrate. A high algal community in coral reef ecosystems describes that there is space competition for coral reef conditions in Labuan Banten waters.
Keyword: Algae, Kualitas Air, Labuan Banten

Judul: Algorithm Construction of HLI Hash Function
Abstrak: Cryptography is a study of mathematical techniques related to aspects of information security regarding on confidentiality, data integrity, entity authentication, and data origin authentication. Data integrity is a service, which is associated with the conversion of data carried out by unauthorized parties. To maintain data integrity, one can use hash functions. An hash function is a computationally efficient function to map an arbitrary length bitstring to a fixed length bitstring called as hash value. The use of hash function in maintaining the information integrity and authentication is in digital signatures, virus protection, and software distribution. Illustration of the hash function in the integrity and authentication of information that is emailed as follow. The sender sends the information and hash value to the recipient. If the hash value of the information is equal to the hash value that is sent by the sender, then information has not been changed. Otherwise the information has been changed. An hash function has two properties, one way and collision resistance. An hash function is called one way if it is computationally infeasible to find any input such that when given any hash value . Meanwhile an hash function is called collision resistant if it is computationally infeasible to find any two inputs where such that . The purpose of this study is to construct a HLI hash function algorithm, to analyze the speed and security of the hash functions as a results of construction. Furthermore, it is to compare it with SWIFFT. Hash function is constructed based on the result of algebraic operations on modular polynomial ringwith . Modular polynomial ring noted as is a set of all polynomials of degree at most with coefficients in . can be represented as a set of integer vector of modulo in dimension . So, it is simple to implement in a computer. In vector operations, is lattice . Furthermore, alattice that is defined from certain polynomial ring is called ideal lattice. HLI hash function is consists of addition and multiplication algorithm in the ring. Addition algorithm consists of sumation operations of modulo and multiplication consists of multiplication operations of modulo . Generally, algorithm of HLI hash function consists of multiplication operations of modulo and addition operations of modulo . However, if the input is binary number then multiplication algorithm only consists of multiplication operation of modulo , so algorithm of HLI hash function consists of multiplication operations of modulo and addtion operations of modulo . An hash function is secured if it has two properties, i.e., one way and collision resistance. HLI hash function hash is one way, it is following the proof of Micciancio. It is has collision resistant because of polynomial is irreducible over and monic. Moreover, it is proved that for every unit vector , the vector is small vector. If the input of hash function is a binary number then HLI hash function only involves addition operations of modulo . So the time that used almost same with SWIFFT. The excellence of HLI hash function is the key size smaller than SWIFFT. This effect on
Keyword: hash function, modular polynomial ring, lattice